Site24x7's Guidance Report for Amazon Web Services examines configuration and resource utilization of AWS services like EC2, RDS, IAM, S3, SES, etc. and provides recommendations to optimize costs, improve fault tolerance and performance of your AWS account.
The recommendation checks are grouped by the AWS service namespace.
An instance is deemed to be idle by analyzing CloudWatch performance counters: CPU utilization, network in and network Out. If the CPU usage of the EC2 instance is less than 2% and the total number of bytes transmitted and received on all network interfaces is less than 1000 bytes, then the EC2 instance is flagged as Idle.
For Amazon EC2 you're billed for any time your instance remains in a running state, even partial hours get taken into account. To reduce associated costs, you can consider stopping/terminating instance or scale down instance size.
"ec2:DescribeInstances" "cloudwatch:GetMetricData", "cloudwatch:GetMetricStatistics", and "cloudwatch:ListMetrics"
Checks the resource utilization of Amazon Elastic Compute Cloud (EC2) instances and labels them as underutilized if the CPU usage is less than 2% for the past 48hrs.
For Amazon EC2 you are billed based on the instance type and the number of consumed hours. You can lower your costs by identifying and stopping low utilized instances.
"ec2:DescribeInstances", "cloudwatch:GetMetricData", "cloudwatch:GetMetricStatistics", and "cloudwatch:ListMetrics"
Checks the security group of monitored EC2 instances for rules that allow unrestricted access on the following ports: 20, 21, 22, 1433, 1434, 3306, 3389, 4333, 5432, or 5500.
Unrestricted access can lead to DDoS attacks or malicious traffic reaching your application.
Expose TCP ports 80 and 443 to the Internet, and minimize the opportunities for an attacker.
Checks whether the allocated Elastic IP address is associated with an active EC2 instance or network interface.
Elastic IP is a static, public IPv4 address. When you associate an Elastic IP to an EC2 instance, or network interface, the already existing public IP address of the instance gets released back into the available address pool. With an Elastic IP address, you can hide the failure of an instance or resource, by disassociating the IP address from the resource and remapping to a different one in the same account.
For efficient utilization, Amazon Web service limits the number of Elastic IPs to 5 per Region for all accounts. Also, a small hourly fee gets levied on unused addresses. So either associate the Elastic IP with an active instance/interface or release it back to the pool.
Checks the configuration of EC2 instances to see whether termination protection is enabled.
Termination protection safeguards your instance from accidental deletion and also ensures AutoScaling policy doesn't terminate a specific EC2 instance while scaling in.
EC2 instance termination protection is disabled by default. Enable to protect against unexpected instance termination.
Checks and identifies Amazon EC2-VPC security groups that have more than 50 inbound and outbound rules.
When you launch an instance in a VPC, you can specify up to five security groups that get associated with the instance. For each security group, you can add rules that control inbound and outbound traffic. Instance performance can be affected if the security group has a large number of rules.
Delete unnecessary or overlapping rule in an EC2-VPC security group.
Checks for Amazon EC2-VPC instances that have security groups with more than 50 rules (inbound and outbound).
Reduce the number of rules configured in the associated VPC security group.
Checks Elastic Compute Cloud (EC2) instances for user-defined tags (Key-value pair).
AWS allows users to assign metadata in the form of tags (key-value pair) to better track and manage instances, images, and AutoScaling groups. Organizations come up with relevant tag groupings and practical tagging strategies to efficiently manage their EC2 resource farm.
Create a tagging strategy adhering to AWS best practices.
Checks the performance counters for Amazon EC2 and identifies instances that appear to be highly utilized.
The average daily CPU usage for the EC2 instance is more than 90% for the last 7 days.
The average daily memory utilization for the EC2 instance is more than 90% for the last 7 days (Only applicable if you've deployed our agent on the EC2 instance).
Consider changing the instance size or add the instance to an Autoscaling group.
As you may already know the AWS systems housing your EC2 instances are hosted in high availability data centers. Auto Scaling lets you take advantage of this geographical isolation by allowing you to distribute Auto Scaling groups across multiple Availability Zones.
Remove a single point of failure and increase the availability of your application.
Checks and identifies launch configurations with invalid or deleted security groups.
Launch configuration determines the type of EC2 instance (AMI, instance type, storage, tags, etc.) that Auto Scaling creates for you. The instance will fail to launch if the name of the security group mentioned in the launch configuration does not exist.
Create a new launch configuration and update it to the AutoScaling group.
Checks the configuration of monitored EC2 instances and identifies resources with no IAM role.
In a microservices architecture, the application running on EC2 instances needs to access resources running on other AWS services (S3 bucket, Lambda, DynamoDB, etc.) To enable, you can either create and distribute AWS credentials to the instances (and take up the overhead of rotating or updating them in the future) or delegate permission to make API requests using IAM roles.
Create an IAM role for your EC2 instances to delegate permissions or to perform actions on your behalf.
Checks for Elastic Compute Cloud (EC2) instances not associated with any AutoScaling Groups.
AutoScaling helps you to scale up and scale down your compute resources based on demand. By creating groups of EC2 instances called as AutoScaling groups, you can specify the desired capacity or assign policies, to ensure an optimum number of EC2 instances are available to handle incoming application requests.
Organize your EC2 instances as AutoScaling groups.
Checks for Elastic Compute Cloud (EC2) instances launched in the EC2 Classic platform.
The Amazon EC2 network is categorized into two platforms - EC2 Classic and EC2 VPC. When you launch an instance within the Classic platform, your instance gets launched in a network that is shared by other AWS tenants. Whereas when you launch instances in a VPC, your resources are logically isolated from the other networks.
Migrate your instances to a VPC.
System status checks are automated checks that are performed by Amazon EC2. This check monitors the operational reliability of the AWS physical infrastructure hosting your EC2 instance.
Set up automated actions to restart the instance. If the instance is regularly failing system checks, try replacing the instance or change to a current generation instance type.
Instance status checks are automated checks that are performed by Amazon EC2 itself. This check determines the health of the instance by sending an address resoulution protocol (ARP) request.
Check OS and network configurations, retrieve system logs to troubleshoot or set up automated actions to restart instance.
Checks Elastic Compute Cloud (EC2) instances for scheduled maintenance events.
From time to time, AWS would schedule a system maintenance event for your instance to perform routine maintenance tasks on the underlying physical host.
Associate the monitored EC2 instance to Site24x7's smart maintenance window to suppress alerts and continue monitoring during downtime.
Checks configuration for Amazon Virtual Private Gateways (VGWs) and identifies unused VGWs that are not associated with the VPC side of the VPN connection.
Every unused (detached) AWS Virtual Private Gateway should be removed from AWS account to facilitate better management and to prevent from reaching service limit.
Identify and remove any unused Virtual Private Gateways provisioned within your AWS account to avoid reaching service limit (by default, you are limited to 5 VGWs - attached or detached - per AWS region).
Ensures that the state of your AWS Virtual Private Network (VPN) tunnels is UP to ensure network traffic flow over your Virtual Private Network.
Continuous monitoring for your VPN tunnels will help you take immediate actions in the event of a failure, in order to maximize uptime and ensure network traffic flow over your Amazon VPN connections at all times.
If your AWS VPN connection tunnels are currently offline, ensure that your firewall configuration is allowing the VPN connection tunneling in the firewall policy.
Ensures that the Amazon VPC peering connection configuration is compliant with the desired routing policy.
Proper configuration of the VPC peering connection routing tables restrict traffic only between the desired resources, hence, leading to an effective way of minimizing the impact of security breaches as AWS resources outside of these routes become inaccessible to the peered VPC.
Determine if the routing tables associated with your peered VPCs implement the right routing policy.
Ensures whether Virtual Private Cloud (VPC) Flow Logs feature is enabled in all applicable AWS regions or not.
Once enabled, VPC Flow Logs will start collecting network traffic data to and from VPC, thus helping you detect and troubleshoot security issues and make sure network access rules are not overly permissible. You also get notified when abnormal activities are triggered within your VPC network such as rejected connection requests or unusual levels of data transfer.
Enable Flow Logs for your AWS VPC.
Ensures that an Elastic IP is allocated for each NAT gateway that you want to deploy within your AWS account.
Allocating Elastic IP for NAT Gateways, use a NAT device to enable instances in a private subnet to connect to the internet or other AWS services, but prevent the internet from initiating connections with the instances. You can mask the failure of an EC2 instance by rapidly remapping the address to another instance launched in your VPC.
Allocate an AWS Elastic IP for each NAT gateway that you want to deploy within your VPC.
Ensures that your AWS application is not deployed with thedefault Virtual Private Cloud so as to follow security best practices.
A default VPC is suitable for getting started quickly, and for launching public instances such as a blog or simple website, however, when you deploy complex applications and use multi-tier architectures you may need to create a non-default VPC that suits your specific requirements.
Create a own (non- default) VPC that suits your specific requirements and migrate your custom AWS applications to it.
Ensures AWS VPC Managed NAT (Network Address Translation) Gateway service is enabled for high availability (HA).
AWS provides two types of NAT devices: a managed NAT gateway and a NAT instance. Using the AWS VPC Managed NAT Gateway service that has built-in redundancy for high availability enables EC2 instances sitting in a private subnet to connect to the internet or with other AWS components.
Enable the Managed NAT Gateway service for your AWS VPC network(s).
Ensures that your NAT gateways are deployed in at least two Availability Zones (AZs).
If you have EC2 instances in multiple Availability Zones and these share one NAT gateway, in the event of AZ failure the NAT gateway becomes unavailable and the resources within other Availability Zones lose internet access. Create fault tolerance by deploying NAT gateways in at least two AZs.
Remove a single point of failure and increase the availability of your application by deploying NAT gateways in atleast two Availability Zones (AZs).
Ensures that Amazon Network ACL DENY rules are effective within the VPC configuration.
AWS Network ACL is an additional layer of defense for your Virtual Private Cloud, basically a network firewall where you can set rules that allow or deny access to a specific port or IP range. An AWS NACL contains a numbered list of rules that are evaluated in order, starting with the lowest numbered rule (e.g. 100), to determine whether the traffic is allowed in or out of the associated VPC subnet(s). The order of the DENY rules within your Network ACLs is crucial as these are evaluated in order and any ineffective or deficient DENY rule can be applied regardless of any higher-numbered rule that may contradict it.
Reconfigure any ineffective or mis configured AWS NACL DENY rules in order to block the traffic to the necessary port at the subnet level.
Ensures no Amazon Network ACL allows inbound/ingress traffic from all ports.
Regulating the subnets inbound/ingress traffic by opening just the ports required by your applications will add an additional layer of security to your VPC and protect against malicious activity such as such as Denial of Service (DoS) attacks or Distributed Denial of Service (DDoS) attacks. Manage your AWS NACL inbound rules to implement the principle of least privilege and reduce the possibility of unauthorized access at the subnet level.
Update your AWS NACL inbound rules configuration in order to allow traffic from specific source port or source port range only.
Ensures no Amazon Network ACL allows outbound/egress traffic to all ports.
Controlling the outbound traffic of one or more subnets by opening just the ports required by your applications will add an additional layer of security to your VPC (a second layer of defense after security groups). Manage your AWS NACL outbound rules to implement the principle of least privilege and reduce the possibility of unauthorized access at the subnet level.
Checks whether a custom route table is created and associated with your private subnets in order to control the subnets routing.
To control the routing for your private subnets you need to create custom route tables. Once these VPC resources are created, all the subnets which should be private within web, app and data tiers can be explicitly associated with the new route tables. A route table contains a set of routes that are used to determine where the network traffic is directed. The custom route table associated with private subnets should contain only the default route (0.0.0.0/0) pointing to an AWS NAT Gateway. A private subnet can be associated only with one route table at a time, however, you can associate multiple private subnets with the same route table.
Create custom route table and associate it with your private subnets.
Ensures Amazon VPC endpoints are not exposed to everyone.
When the Principal element value is set to "*" within the access policy, the VPC endpoint allows full access to any IAM user or service within the VPC using credentials from any AWS accounts. Allowing access in this manner is considered bad practice and can lead to security issues. Updating the access policy allows to stop any unsigned requests made to the supported services and resources.
Restrict access to your Amazon VPC endpoints by updating access policy.
Check whether the Amazon Virtual Private Cloud (VPC) endpoints are used to securely connect your VPC to other AWS services.
VPC endpoints enable you to privately access specific AWS services from your own Amazon Virtual Private Cloud, without using public IP addresses and without requiring the traffic data to travel across the Internet.
Enable VPC endpoint to connect with particular AWS services that are outside your VPC network through a private link.
Checks Amazon Elastic Block Store (EBS) volume configuration for associated snapshot ID.
EBS provides persistent block level storage support for your EC2 instances. Snapshots are a point in time, incremental backups of the data stored in your EBS volume. For redundancy, these Snapshots get stored in S3 buckets across multiple Availability Zones. In the event of a failure, these snapshots help you to create new volumes or move volumes across Availability Zones or Regions.
Create weekly snapshots for your EBS volumes.
No recent EBS snapshots taken in the last 30days.
Snapshots record the point in time state of your EBS volume. In the event of a failure replicas of the original volume can be created using these snapshots.
Depending on how frequently you are making changes to your EBS volume, you can set up an automated scheduler to take regular snapshots to improve EBS data protection and recoverability.
Checks instance state of an EBS attached EC2 instance.
EBS volumes continue to persist, regardless of any transitions that an instance undergoes during its life cycle. For EBS volumes you are billed based on the amount of storage you provision and for the IOPS (Only for Provisioned IOPS SSD (io1) Volumes) until the storage is released.
Create a snapshot of the EBS volume and release the storage.
Checks Amazon Elastic Block Store (EBS) volume configuration for associated instance ID.
Elastic block store volumes can persist independently even after instance termination or even after you explicitly unmount and detach the volume from the instance. As you may know, unattached volumes are still charged based on the storage provisioned and for IOPS.
Associate the configured EBS volume, with an active instance or release the storage volume.
Checks the configuration for Amazon Elastic Block Store (EBS) volumes and alerts you if any volumes are unencrypted.
When you enable encryption for an EBS volume and attach it to an EC2 instance, you encrypt all the data inside the volume. Also, all data that moves between your volume and instance gets encrypted.
Encrypt an existing unencrypted volume if it is storing sensitive data.
Checks the configuration for Amazon Elastic Block Store (EBS) volumes and identifies volumes where encryption is enabled using AWS-managed CMK.
Amazon EBS encryption uses the AWS key management service CMKs for encryption. There are three types of CMKs: Customer managed CMK, AWS managed CMK, and AWS owned CMK. Creating your own CMK (Customer managed CMK) gives you more flexibility, including establishing and maintaining key policies, IAM policies, grants and more.
Create a customer managed CMK to encrypt your volumes.
Checks the configuration of monitored classic load balancers to find ELB nodes with no registered back-end instances.
A configured Load Balancer continues to accrue charges, till you delete it. If a load balancer has no registered back-end instances, then it is not being used efficiently.
Either add/register instances to the load balancer or consider terminating it.
Checks the usage stats of monitored classic load balancers deems them as idle if the number of requests received/routed or the number of TCP connections established with the target instance is less than 100 in the past 48hrs.
Amazon Web Services bills you for each partial or full hour your load balancer runs. If your load balancer is routing less then 100 requests, then it is not adequately being used.
Consider terminating and running your application without a load balancer.
"elasticloadbalancing:DescribeLoadBalancers", cloudwatch:GetMetricData", "cloudwatch:GetMetricStatistics", and "cloudwatch:ListMetrics"
Checks the metric "healthy host count" for load balancers and warns when the count drops below the threshold.
The load balancer performs health checks on all registered instances to find whether the instance is healthy or not. However, sometimes the default health check configuration can be overly restrictive and can deem heath instances as unhealthy.
Create your own health check configuration and configure optimum interval—healthy/unhealthy threshold, and timeout.
Checks for load balancers operating in a single Availability Zone.
If you are launching EC2 instances in a single Availability Zone, then any failure occurring in that data center could render all of your instances unavailable. By deploying multiple EC2 instances to different Availability Zones in the same Region, you remove a single point of failure.
For increased resilience and fault tolerance, please ensure the EC2 instances registered to your load balancer is attached to different Availability Zones.
Checks for Elastic load balancers where Cross-Zone load balancing is disabled.
By default Cross-Zone load balancing is not enabled for your classic type Elastic Load Balancer. Generally, a load balancer equally distributes incoming traffic across configured Availability Zones. However, there could be a mismatch in the load if you are not running an equivalent number of EC2 instances in each zone. This could easily happen as instances could get manually deregistered or detached due to health check failures or removed for maintenance. If cross-zone load balancing is enabled, then Elastic Load Balancer equally distributes application traffic to all registered instances.
Checks the configuration of your load balancers to see if Access Logs is enabled for your ELB.
Access logs capture and stores in-depth information for each request received by the Load Balancer. Information like IP address, latencies, request path, back-end server response gets stored in an Amazon S3 bucket that you specify. AWS account holders can use this to analyze traffic patterns and troubleshoot advanced ELB issues.
This is an optional feature that is disabled by default. Enable Access logs for your Elastic Load Balancer.
Checks configuration of monitored Elastic Load Balancers to identify ELB nodes where Connection Draining is disabled.
When an EC2 instance gets terminated or deregistered from an AutoScaling group due to a health check failure, the ELB stops routing new requests to that instance and abruptly closes the active connection. If Connection Draining is enabled, the ELB will keep the connection open for active sessions to complete.
Enable Connection Draining for your load balancer.
Checks the configuration of Elastic load balancers (Classic and Application type) and warns you when there are no listeners that use the secure protocol (HTTPS or SSL).
A listener is a process that checks for connection requests. When your Elastic Load Balancer has no configured HTTPS listeners, unauthorized parties can read the data sent across the network between the client and your load balancer.
Enable SSL/TLS support for the HTTP listener by deploying an SSL certificate on your load balancer.
Checks the created time of access keys and identifies IAM users with keys that are older than 90 days.
Access keys consist of access key id and secret access key and they are used to programmatically sign requests to AWS API endpoints.
As a security best practice, you can shorten the period an access key is active by rotating access keys on a regular schedule.
Checks for IAM groups with inline policies.
IAM policies are JSON policy documents that you can assign to an entity – IAM user, role or group. A key advantage of using managed policies is that they are maintained and updated by AWS as new services, and APIs get introduced.
Use AWS managed policies to grant permission to IAM groups.
Checks each IAM user in your account and identifies users where the managed policy AdministratorAccess is assigned.
The AdministratorAccess policy grants permissions for all four access level viz. List, Read, Write and Permissions management. Unrestricted admin access can easily lead to orphaned resources, security issues, and unexpected spikes in AWS bill.
When you are assigning permissions to IAM users follow the practice of granting least priviledge–that is, grant only the permissions required to perform the task.
Checks each IAM role in your account and identifies roles where the managed policy AdministratorAccess is assigned.
The AdministratorAccess policy enables the users assuming the role to perform all actions including read resource content, create, delete or modify resources, and modify resource permissions.
Assign this policy only to the account administrator. Regularly review or audit the IAM policies assigned to other roles to keep your resources secure.
Checks for IAM users with two active Access Keys.
IAM users use Access Keys to make secure REST or HTTP requests to AWS service APIs.
As a best practice try to keep only one key active.
Checks the age of the console password for IAM users with no programmatic access and warns when they remain unused.
Console passwords are used by IAM users to sign into the AWS management console. By deleting the unused IAM user or disabling the password, you can add an extra layer of security to your AWS account.
Delete the unused IAM user.
Checks the age of the console password for IAM users with no programmatic access, and warns when they have not been used in the last 90days.
Delete the inactive IAM user or disable the sign-in credentials.
Checks whether multi-factor authentication(MFA) is enabled for the root account or not.
Use a security token-based MFA to protect your AWS account.
Checks whether an IAM group is created for the AWS account or not.
As you may already know you can provide your team members the ability to sign in to the AWS console or make programmatic requests to AWS services by creating IAM users. Instead of attaching policies directly to a user or manually editing user's permissions, you can create an IAM group (collection of IAM users) for easier management.
Create multiple IAM groups with different permission scopes.
Checks whether a password policy is set for your AWS account.
You can create a password policy to enforce complexity requirements (password length and character type) and rotation periods for your IAM user passwords.
Set a password policy to enforce strong password creation.
Checks the list of attached IAM policies for each IAM role for a policy named "AWSSupportAccess."
The managed policy "AWSSupportAccess" grants an IAM user access to file and manage cases in the AWS Support Center.
Make sure that there is at least one IAM user in your AWS account with permission to create and manage support cases.
Checks the AWS account root user for active access keys.
Access keys are used to make secure REST API or HTTP query requests to AWS service APIs. Anyone with AWS root account user access keys can gain unrestricted access to all the resources, including billing data using these keys.
Delete access keys for the root user or make it inactive.
Checks the bucket and user policy (not access control lists) of monitored S3 buckets to identify publicly accessible buckets.
Publicly accessible means anyone in the world can read the bucket by listing the objects that are stored and upload/remove objects. As you may already know, for S3 you're charged based on the request type, quantity of requests and the volume of data retrieved. Frequent list API requests from unintended public users can quickly lead to high charges.
Determine if the bucket in question truly requires public access. If not, restrict access and make the resource private.
Checks and identifies Amazon S3 buckets where default S3 encryption is disabled.
Server-side encryption or encryption at rest ensures Amazon S3 encrypts your data at the object level.
Checks and identifies, Amazon S3 buckets where server access logging is disabled.
By default Amazon S3 doesn't collect server access logs. By enabling logging, you can store details about a single access request – requester, bucket name, request time, response status and more on a target bucket of your choice. There is no extra charge for enabling server access logging. However usual charges for storage are applied.
Enable server access logging for your S3 buckets to help with your security and access audits.
Checks the configuration of Amazon S3 buckets and identifies buckets where MFA delete is disabled.
MFA delete enabled buckets required additional authentication for version state changes and permanent delete operations.
Add a layer of security to your S3 bucket by enabling MFA Delete.
Checks RDS-VPC security groups for inbound rules that has a source IP address with the CIDR notation 0.0.0.0/0.
VPC security group controls traffic access to a DB instance. You can add rules in a security group that allows access from specific IP range, port or EC2 security group.
Restrict access to a specific IP address to prevent malicious activity.
Checks the accessibility options and identifies DB instances that are publicly accessible.
An internet facing DB instance with a publicly resolvable DNS name can increase the opportunity of risks and unexpected data transfer charges.
Disable the publicly accessible flag.
Checks the configuration and identifies RDS DB instances where automated backups are disabled.
Amazon takes storage volume backups of your entire DB instance at regular intervals and retains the backups for a specific number of days to help point in time recovery.
Enable automated backups for RDS instances for a smooth data restoration.
Checks and identifies Amazon RDS DB instances where encryption is not enabled.
Encrypt data at rest for RDS, including underlying storage, automated backups, read replicas and snapshots to provide an additional layer of protection.
Enable encryption for an RDS DB instance during creation or encrypt a copy of a DB snapshot and then restore a DB instance from the encrypted snapshot.
Checks for DB instances deployed in a single Availability Zone(AZ).
In a Multi-AZ deployment, Amazon automatically provisions a standby in a different AZ and synchronously replicates data. When a failure or planned maintenance occurs, Amazon RDS automatically performs a failover to the standby without any manual intervention.
Provision a Multi-AZ DB instance or modify an existing DB instance to be Multi-AZ deployment.
Checks the CloudWatch performance counters for Amazon RDS and identifies DB instances that appear to be highly utilized.
The average daily CPU usage is more than 90% for at least 4 days in the last 7 days.
The amount of disk space consumed is more than 85% for at least 4 days in the last 7 days.
Vertically scale up your master database or use read replicas to meet the demands of your application.
Checks the CloudWatch performance counters for Amazon RDS instances and identifies DB instances that appear to be underutilized.
The average daily CPU usage is less than 20% for at least 4 days in the last 7 days.
The average number of daily database connections is less than 100 for at least 4 days in the last 7days.
For Amazon RDS you pay for compute capacity by the hour your DB instance runs. If your DB instance is receiving fewer connections or is consuming meager amounts of CPU you can consider taking a snapshot and deleting the instance to reduce costs.
Checks the topic access policy of your Amazon SNS topics for topics that allow everyone to publish.
Allowing any AWS user or resource to publish message could lead to an unexpected increase in SNS publish charges.
Allow only the topic owner and specific users to publish messages.
Checks topic access policy of Amazon SNS topics for topics that allow anonymous subscription.
Allowing everyone to subscribe can end up breaking message confidentiality. For example, any unauthorized entity can now subscribe to the topic and received the messages that get published.
Limit subscription to the topic owner or particular endpoints to maintain topic security.
Checks for SNS topics with HTTP endpoint as subscribers.
Amazon Simple Notification Service (SNS) is an asynchronous message delivery service the works on the publisher-subscriber paradigm. When you subscribe an HTTP/HTTPS endpoint to a topic and publish a message, SNS sends a POST request delivering the contents of the message to the said endpoint. However, messages sent over HTTP can be vulnerable to eavesdropping.
When you subscribe a URL choose HTTPS over HTTP.
Checks for Amazon DynamoDB tables where table throughput is manually managed.
When you create a table in Amazon DynamoDB you specify capacity requirements for read and write activity. Estimating adequate capacity or manually adjusting provisioned capacity based on demand can become an operational burden in the long run when you're dealing with cyclical or unpredictable DB workloads.
Dynamically adjust table throughput capacity in response to traffic patterns automatically with DynamoDB Auto Scaling.
Checks for Amazon DynamoDB tables with no backups in the last 30 days.
Data archival is a critical aspect of long-term data retention and regulatory compliance requirements. Amazon DyanomDB lets you create full backups for you tables in seconds and helps you restore data anytime with zero impact on application performance or availability.
Execute the backup and restore operations for your DynamoDB tables using the AWS management console or DynamoDB APIs.
Checks for Amazon DynamoDB tables where encryption at reset is disabled.
Enable encryption at rest for your data (tables, local secondary indexes, and global secondary indexes) using an AES-256 and service-default AWS Key Mangement Service (KMS) key to protect sensitive information and achieve compliance requirements.
You can't enable encryption at rest on an existing table. Create a new encrypted table using the AWS management console or APIs.
Checks the Amazon DynamoDB tables running at the time and alerts you if the total item count is zero.
As you may already know, for DynamoDB you either pay for the manually provisioned throughput or for the resources Amazon provisions to maintain your target read and write capacity. So any configured table continues to accrue charges. If a table has no data, then it is not efficiently being used.
Consider deleting the unused table.
checks the configuration of SQS queues and warns you when server-side encryption is disabled.
Server-Side Encryption (SSE) encrypts the message body to help you reliably exchange sensitive data between distributed application components or microservices.
Enable server-side encryption for your existing queue or enable the option during queue creation.
Checks for SQS queues where default AWS managed CMK is used to enable server-side encryption.
When you enable server-side encryption you choose a key provided by AWS Key Management Service (KMS) to encrypt messages stored in your standard and FIFO queues. You can either use the default AWS-managed Customer Master key (CMK) or create and manage your own keys for better flexibility, access control, rotation, and deletion.
Checks for the wildcard (*) usage in the principal element for SQS queue Access Policy.
The principal element in a policy specifies which AWS account or service or user has access to the queue. The wildcard (*) value in the principal element means that your queue is open to all AWS accounts. Overtly open access for your SQS queue could lead to unauthorized message delivery.
Allow Amazon SQS access based on an AWS account ID.
Checks and identifies standard or FIFO queues with no designated dead letter queue.
A dead letter queue is an undelivered message queue to which messages get sent when a consumer does not successfully process them. Users can use this holding queue to isolate and troubleshoot problematic messages and determine why they failed.
Dead letter queues can't be configured for existing queues. Configure a new SQS source queue and create a second queue as a dead letter queue.
Checks the SQS CloudWatch metric: Approximate number of messages visible and alerts you when the number exceeds 100 for 3 consecutive polls.
Amazon SQS offers a fully managed hosted queue service to help integrate distributed application components. The metric "Approximate number of messages visible" provides insight about active queue size and backlog. If the metric keeps on increasing it could indicate a stuck or slow queue.
Check the resource usage of your consumers (EC2 instances, Lambda functions, ECS instances) to identify and troubleshoot the problem.
Checks for Amazon SES identities both email address and domain with the pending verification status.
In Amazon SES, an identity is an email address or domain that you can use to send email. Before you begin, you must verify each identity that you're going to use as From, Source, Sender or Return-Path address. If you're using the Amazon SES sandbox, you need to verify the recipient addresses as well.
Resolve issues with the verification process immediately.
Checks for SES identities (domain and email addresses) that are not configured to use DKIM signatures.
Domain Keys Identified Mail (DKIM) is an email authentication protocol that allows senders to sign a particular representation of an email message cryptographically. The receiving mail server uses this signature to check whether any third party modified the message in transit.
Automatically add a DKIM signature to every email you send using Easy DKIM in Amazon SES or manually add your own DKIM signature.
Checks for Amazon Kinesis Data Streams where server-side encryption (SSE) is enabled by AWS managed CMKs.
CMKs (Customer Master Keys) are the primary resource used to encrypt and decrypt data. There are three types: customer managed CMKs, AWS managed CMKs, and AWS owned CMKs. You can either encrypt data in your Amazon Kinesis Streams using AWS managed CMKs or create your own customer managed CMKs for more control and flexibility.
Use customer managed CMKs to encrypt data at rest within the Kinesis Data Stream service.
Checks for Amazon Kinesis Data Streams where Server-side-encryption (SSE) is disabled.
Encryption at rest plays a crucial part in data management and helps your application meet strict compliance and regulatory requirements. By enabling server-side encryption you data gets automatically encrypted as it enters and decrypted as it leaves the stream service.
Enable Server-side-encryption for you live stream using the Amazon Key Management (KMS) keys.
Checks the configuration for Web Application Firewall (WAF) and identifies unassigned Web ACLs.
For AWS WAF you're metered based on the number of Web Access Control list and the number of rules that you add per web ACL regardless of whether they are associated with a resource—CloudFront distribution/Application Load Balancer or not.
Consider deleting unused web ACLs (Note: You have to remove rules and disassociate all CloudFront distributions and Application Load Balancers from the ACL before deletion).
Checks the performance counters for Amazon Redshift and identifies clusters that appear to be underutilized.
Checks the performance counters of running Amazon Redshift clusters and flags them as idle if they meet the following criteria.
The average number of database connection is less than 10 for the last 7 days.
The cluster-wide CPU utilization is less than 5% for the last 7 days.
The average number of read and write operations across the cluster is less than "x" for the last 7 days.
Note: You can change the default alert criteria using Advanced configurations.
Checks the performance counters for Amazon Redshift and identifies data warehouse clusters with high disk usage.
Checks the metric: percentage disk space used (across the cluster) and alerts if you if the value is more than 90% on at least 4 of the last 7 days.
Checks the network configuration for Amazon Redshift and identifies data warehouse clusters that are publicly accessible.
A publicly accessible cluster (public IP) can be accessed by any machine from the internet thus increasing the opportunity of security risks.
Limit connection to your cluster from only within the VPC.
When audit logging is enabled, detailed information about authentication attempts, connections, disconnections, user activity, changes to DB user definitions and more are captured and uploaded to a S3 bucket.
Enable audit logging for security and troubleshooting purposes.
Checks the parameter groups for Amazon Redshift and identifies clusters where the require_ssl parameter is set to false.
By default cluster databases accepts client connections whether it uses SSL or not. However, establishing an unencrypted communication between your client and data warehouse clusters can lead to security vulnerabilities.
Checks the configuration of AWS Lambda and alerts you if any functions are publicly accessible.
As you may already know, for Lambda you are charged based on the number of requests and AWS counts a request each time a function starts executing in response to an event notification or invoke call. Allowing unauthorized executions can lead to unexpected charges on you AWS bill.
User Lambda function policies to manage invocation permissions.
Checks configuration for Lambda functions and alerts when tracing is disabled.
Enable active tracing for your Lambda functions.
Checks the host-level metrics for Amazon ElastiCache and identifies nodes that appear to be underutilized.
The percentage of daily CPU usage is less than 10% for at least 4 of the last 7 days.
The percentage of daily Engine CPU usage (Only for Redis Engine) is less than 10% on at least 4 of the last 7 days.
Remove nodes from your cluster or change to a smaller node type.
Checks the configuration for ElastiCache Redis and identifies clusters where Multi-AZ is not enabled.
During planned maintenance or in the unlikely event of node/Availability Zone failure you have to recreate and provision a new primary node manually. Instead you can enable Multi-AZ and allow ElastiCache to automatically promote a read replica as a primary and complete failover within seconds.
Enable Multi-AZ with Automatic Failover using the ElastiCache management console or APIs.
Checks if Amazon CloudFront web distributions are integrated with the Web Application Firewall (AWS WAF).
AWS Cloudfront—WAF integration enables you to block any malicious requests made to your Cloudfront Content Delivery Network based on the criteria defined in the WAF Web Access Control List (ACL) associated with the CDN distribution. It helps protect against application-layer attacks that can compromise the security of your web applications or place unnecessary load on them.
Create the required WAF Access Control List and associate it with the appropriate web distribution to integrate CloudFront with AWS WAF.
Checks if Amazon Cloudfront distributions have Access Logging feature enabled.
The Cloudfront access logs contain detailed information (requested object name, date and time of the access, client IP, access point, error code, etc) about each request made for your web content, information that can be extremely useful during security audits or as input data for various analytics/reporting tools.
Enable access logging for your Cloudfront CDN distributions.
Checks whether the communication between your Amazon CloudFront CDN distribution and its end users is encrypted using HTTPS.
Establishing communication with HTTPS (SSL encryption) for your CloudFront CDN distribution can guarantee that the encrypted traffic between the edge (cache) servers and the application viewers cannot be decrypted by malicious users in case they are able to intercept packets sent across the CDN distribution network.
Configure CloudFront distribution viewer protocol policy to enforce HTTPS for data in transit encryption.
Checks whether field-level encryption is enabled for your Amazon CloudFront web distributions.
CloudFront field-level encryption lets you add an additional layer of security, along with SSL encryption (HTTPS), helping you protect specific sensitive data throughout system processing so that only certain applications within your environment can see this data.
Enable field-level encryption for your Amazon CloudFront web distributions.
Ensures that AWS CloudFront distributions origin(s) do not use insecure SSL protocols.
Using insecure and deprecated SSL protocols for your Cloudfront distributions could make the connection between the Cloudfront CDN and the origin server vulnerable to exploits such as POODLE (Padding Oracle on Downgraded Legacy Encryption). You're strongly recommended to use TLSv1.0 or later (ideally use only TLSv1.2 if you origins support it) and avoid using the SSLv3 protocol.
Remove the deprecated SSLv3 protocol from your Cloudfront distributions origin.
Checks whether the communication between your AWS CloudFront distributions and their custom origins is encrypted using HTTPS.
Using HTTPS for your AWS Cloudfront distributions can offer you the guarantee that the encrypted traffic between the edge servers and the custom origin cannot be unsealed by malicious users in case they are able to capture packets sent across Cloudfront Content Distribution Network (CDN). It helps you secure the delivery of your web content and fulfill compliance requirements for data in transit encryption.
Enable HTTPS for encrypting the traffic between your CloudFront distributions edge locations and their origins.
Checks if your Amazon API Gateway APIs are using SSL certificates to verify that HTTP requests made to your backend system are from API Gateway service.
To ensure that the HTTP requests made to your backend services are originating from your Amazon API Gateway APIs, it is strongly recommended to use client-side SSL certificates to verify the requester's authenticity.
Generate an SSL certificate and associate it with your Amazon API Gateway API.
Checks if AWS CloudWatch logging is enabled for APIs created with Amazon API Gateway.
Amazon CloudWatch logging facilitates recording information about the API execution at the stage level. This information can be extremely useful for troubleshooting any issues that you have with your APIs.
Enable AWS CloudWatch Logs for your Amazon API Gateway APIs.
Checks if Content Encoding feature is enabled for your Amazon API Gateway APIs.
Amazon API Gateway allows your client to call your API with compressed payloads using one of the supported compression types. Once Content Encoding is enabled, the API Gateway service allows compression of response bodies based on client's Accept-Encoding header. Enabling compression for your API payload will help you improve your API performance and reduce bandwidth utilization.
Enable Amazon API Gateway API payload compression using Content Encoding feature.
Checks whether detailed CloudWatch metrics are enabled for all APIs created with AWS API Gateway.
AWS CloudWatch metrics for API stages allow you to fetch more granular metric data which can help you to act fast and take immediate actions based on information delivered by these metrics through alarms.
Enable detailed CloudWatch metrics for your Amazon API Gateway APIs stages.
Checks if your Amazon EFS file systems are encrypted using KMS Customer Master Keys (CMKs) instead of AWS managed-keys (default keys used by the EFS service when there are no customer keys defined).
Upon defining and using your own KMS CMK customer-managed keys to protect the EFS file systems data and metadata, you gain full control over who can use these keys to access the data (including the system metadata). The AWS KMS service allows you to create, rotate, disable and audit CMK encryption keys for your file systems and helps you have more granular control over your data-at-rest encryption/decryption process.
Encrypt an existing AWS EFS file system with your own AWS KMS CMK customer-managed key.
Checks whether your Amazon EFS file systems are encrypted to protect your data at rest.
Encryption keys are managed by AWS KMS service, eliminating the need to build and maintain a secure key management infrastructure. Your data is transparently encrypted while being written and transparently decrypted while being read from your file system, therefore the encryption process does not require any additional action from you or your application. It's strongly recommended to encrypt your EFS file systems in order to protect your data and metadata from unauthorized access, and thereby enforce compliance requirements for data-at-rest encryption within your organization.
Enable Encryption for your AWS EFS file system.
1. What is Site24x7's Guidance Report for AWS?
The Guidance Report inspects your AWS environment and helps you identify opportunities to effectively use resources like EC2 instances, EBS volumes, ELB nodes and more.
2. Is the Guidance Report available to all users?
Yes. Site24x7's Guidance Report for AWS is available for all Site24x7 subscription holders, both paid and eval. All you need to do is enable access either via IAM user creation or cross-account IAM role and connect your AWS account with Site24x7.
Currently, our report only offers recommendation checks for select AWS services—EC2, EBS, ELB, SES, RDS SNS, DynamoDB, and S3.
The compliance of only monitored resources is examined. Resources that were excluded using various auto discovery filters are not taken into account.
4. How can I access the Guidance Report?
Sign in to the Site24x7 web console. choose AWS from the left navigation pane and choose the AWS account for which you want to view recommendations.
In the menu drop down, choose Guidance Report.
A duration of one hour (from the time of AWS account integration) is required to build the Guidance Report. Once done, you can sign in to the Site24x7 console, choose the monitored AWS account > Guidance Report to view the recommendations.
5. How frequently will the report update?
The Guidance report will be updated every week from the time of AWS account integration.
6. What about Email notifications?
Weekly email updates to the Super Admin contact associated with your Site24x7 subscription account will be sent.
7. Can I schedule the report?
Yes. You can choose frequency (daily, weekly or monthly), time of the day and the user group using the Scheduled Reports feature.
8. Will newly monitored resources show up in the Guidance Report?
The report will be updated and refreshed every week and any new resources discovered and monitored during this period not complying with our checks will be included in the report.
9. How does Site24x7 collect the data required to make the recommendation?
Site24x7 makes uses of various AWS service level APIs to collect configuration information. The resource usage metrics collected by polling CloudWatch APIs are used to identify idle/unused resources.


The Trinity Certificate in TESOL Course is for people who want an internationally recognised qualification and practical course of teacher training.
Below is an outline of the main features of our TESOL course. If you have any other questions please contact us or check our Frequently Asked Questions.
When you enrol for one of our TESOL courses (following a successful face-to-face or telephone interview), we will send you a substantial pre-course task, designed to raise your awareness of teaching methodology and the grammar and phonology of English. Depending on your prior knowledge, this can take anything up to 20 hours to complete. You will be asked to buy (around €40) "How to teach English" by Jeremy Harmer (Longman), an excellent introduction to English language teaching, and complete some tasks which will be handed in (but not assessed) at the start of each TESOL course.
The practical nature of the TESOL course is emphasised from the very beginning. On the full-time TESOL course, trainees are divided into teaching practice groups on the first day and begin their teaching practice on the second day. Each group is assigned a practice class of real Spanish students and a teaching practice tutor. Teaching practice includes teaching preparation session and a feedback session where the teaching practice tutor discusses the lesson with you and gives you guidance on the teaching points for the following lesson. Halfway through the TESOL course the teaching practice groups change class. In this way, trainees have an opportunity to teach students whose English is at a different level.
During these sessions of the TESOL course you will acquire and practise a wide range of teaching skills found in mainstream current English Language Teaching. A large number of activities and areas are covered in detail and these are all of immediate practical value for planning your teaching practice lessons. Video is used in some sessions and observations of both peers and tutors of the Active Language teaching staff provide further insights into lesson planning, staging and management.
We believe in learning through involvement, and students are expected to participate in many different ways during the input sessions. Each input session of the TESOL course addresses specific language areas and TEFL teaching techniques. These are commonly presented via a workshop approach, where your tutor acts as a facilitator rather than a lecturer.
These input sessions cover areas of grammar and phonology and are designed to provide TESOL course trainees with a basic working knowledge of these TEFL subjects and how to teach them effectively. Trainees find these sessions of the TESOL Course particularly rewarding (and challenging!), as most native speakers of English have had very little previous opportunity of studying the nuts and bolts of their own language.
You will sit a 45-minute written exam towards the end of the TESOL course, which will test your knowledge of grammar and phonology.
During the TESOL course 3 assignments are given: These include a record of your experience learning the unknown language, a case study of one of your students with a diagnosis of their language difficulties and a project where you create original material to be used with your learners.
Your teaching practice, your 3 written assignments and your language awareness exam will all be graded from A to D. A, B, and C are pass grades. D is a fail. You must achieve at least a C grade in all 5 assessed components of the TESOL course to be awarded a Trinity TESOL certificate. If an assignment or your language exam is a D grade you will be given an opportunity to resubmit the assignment before the TESOL course ends, with advice on what you need to do to achieve a pass grade.
Assessment on teaching practice is continuous and is based on both your classroom teaching and your ability to reflect effectively on your own and others' teaching.
You will receive your grades on the Monday after the course has finished.
You will receive 2 certificates. Trinity College awards a certificate to all successful candidates on completion of the TESOL course. In addition, we will award you a certificate with details of your grades, which employers often ask for.
I trained at Active Language in August 2014 and would thoroughly recommend this course to anyone wanting to train in TEFL. The tutors are excellent, the course itself is well structured and extremely interesting and the resources are top quality.
Training with Active was one of the most rewarding, life changing decisions I ever made. I can't imagine a more inspiring, supportive and genuinely lovely team than Dani, Simon and their professional family. The fact they are based in one of the most beautiful cities in the world doesn't hurt one bit either. I whole heartedly recommend!
Overall I found the course extremely challenging and can honestly say that I have learnt things that I have never come across when studying English through high-school, college or university! With this in mind I would recommend the course to others but with the caveat of 'go into it with your eyes open - it is five weeks of very hard work, not a walk in the park'.
I studied with Active Language back in 2007 and found the course to be highly supportive and insightful. I really enjoyed the practicality of the sessions and the tutors there are so approachable it made for a great experience. Cadiz is gorgeous and the whole experience was wonderful, can't recommend it enough.
I just recently completed the 5-week intensive course (Aug. 3 - Sep. 4 2015) and I´m glad I did it! It was very hard work but hard work reaps success and I would recommend this course to everyone who is interested in a TEFL career. The staff is wonderful, constructively guiding you in the right direction and the course aims are very practical. The knowledge I have acquired from A.L. has led me to be a more effective English teacher here in Spain.
I would highly recommend anyone hoping to teach English as a foreign language to enrol on the Trinity TESOL certificate course, at the fantastic Active Language school in Cadiz. In the five short weeks I was a student on the course I have learned an immense amount, made some fantastic new friends and gained a qualification which will allow me to teach English as a foreign language all over the world, which is quite something. I thoroughly enjoyed the course where I was taught by friendly, enthusiastic & thorough tutors. The timetable was well structured and balanced and although the course is intensive I was very well guided through every step of the way. The support I received from the entire team at Active Language was second to none, no question was too big or too small and there was always a friendly ear to listen! The support post course continues and the school provides a careers service for life. I shall definitely keep in touch with Active Language, Cadiz and pop in for a catch up and a natter whenever I am around! I urge you to choose this school to study at if you are planning a career in teaching ESL. You will not be disappointed.


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Home / A' Level / BIOLOGY / Form five / BIOLOGY FORM 5-BIOCHEMISTRY
BIOLOGY FORM 5-BIOCHEMISTRY
A' Level BIOLOGY Form five
ORGANIC CONSTITUENT OF THE CELLS.
Bio chemistry: is the study of structures, properties and functions of chemical constituents of the cells.
It is a great unifying theme in biology.
It finds applications in fields like;
Agriculture; in developing pesticides and herbicides.
Medicine; including all pharmaceuticals.
Fermentation; baking products, food products and breweries.
New development of biology eg genetic engineering.
ELEMENTS FOUND IN LIVING ORGANISMS ARE
Chief/ macro elements: hydrogen (H), carbon(C), nitrogen (N), oxygen (O), phosphorous (P), sulphur(S).
Ions – sodium(Na+) , magnesium (Mg2+) , chlorine( cl–) , calcium (Ca2+) etc.
Trace elements – manganese(Mn) , iron(Fe) , cobalt(Co),copper (Cu) , molybdenum(Mo) and iodine(I).
MACROMOLECULE(S)
Macromolecule is a giant molecule made from many repeating units. The molecules built are polymers and the individual units are monomers.
The units are joined together by a chemical process called CONDENSATION which means removal of water.
The units can be broken down again by an opposite process known as hydrolysis which means adding of water.
The most important macromolecules in biology are;
Polysaccharides( carbohydrates)
Nucleic acids.
And their constituent monomers are; monosaccharide's, amino acids, glycerol, fatty acids and nucleotides respectively.
Others are;
Adenosine triphosphate (ATP).
ORGANIC SUBSTANCES ( CHEMICAL NATURE AND IMPORTANCE)
1. CARBOHYDRATES
They are substances which contain carbon, hydrogen and oxygen with the general formula of (CHO)n where n is a real number.
Characteristics of carbohydrates.
They are either simple sugars or compound sugars.
The compound sugars are formed by condensation of simple `sugar molecules.
They are hydrate of carbon from the proportion of hydrogen and oxygen in water.
The basic carbohydrate unit is thus a sugar which is the derivative of a poly hydrosol alcohol.
Alcohol is the paraffin compound with hydrogen atom replaced by the univalent hydroxyl (OH) group.
Paraffin is aliphatic or chain of compounds of carbon and hydrogen in which the carbon atoms are linked by single bonds to adjacent atoms. (see Example above).
The simpler hydroxyls are the glycol and glycerol and the simplest of sugar is the glycerose (glycerin).
The carbohydrate contains several hydroxyl groups.
4. Some contain aldehyde (-CHO) group and others contain ketone group ( -CO-)
Examples;
Glucose: is a pentahydroxyl alcohol with the aldehyde group.
Fructose: is the pent hydroxyl alcohol with ketone group.
Complex sugars are built from the basic sugar units called monosaccharides through the process of condensation polymerization.
Many sugars are reducing sugars and others are non-reducing sugars but give rise to reducing sugars on hydrolysis with enzymes or mineral acid (mostly dilute HCL)
NB: Carbohydrates are called reducing sugar because they act as reducing agents supplying electrons from their functional groups i.e. the aldehyde and ketone groups which can reduce the cu2+ ions to cu+ ions which appear orange or yellow ppt (precipitate).
The true carbohydrates are saccharides with a combination of sugar units. These are divided into three main classes
monosaccharides – with a single sugar unit
Disaccharides – with two sugar units.
Polysaccharides- with many sugar units.
Sugar which include mono and disaccharides are all soluble in water. They have a sweet taste.
They are crystalline and small molecules. Those with a potentially active aldehyde or ketone group are the reducing sugars e.g. glucose.
Sugar Natural occurrence
Glucose Plant juice and grape sugar
Galactose From fruits.
Fructose From fruits
Maltose From germinating seeds ( cereals)
Sacrose From sugar cane ( in plants)
Lactose From milk
Sugars without potentially active reducing groups are known as non-reducing sugars e.g.
Sucrose (C12H22O11).
Have general formula (CnH2nOn)
All are reducing sugars
They are classified according to the number of carbon atoms e.g.;
Trioses have 3 carbon atoms
Tetraoses have 4 carbon atoms
Pentoses have 5 carbon atoms
Hexoses have 6 carbon atoms
Heptoses have 7 carbon atoms
– Of code, hexoses and pentoses are most common and triose being the true sugar.
– Pentose sugars are never occurring but only in combination with other groups of compounds.
Riboses- this occurs in one kind of nucleic acid. A derivative of deoxyribose
Hexose. The most important free sugar.
D-glucose
D- Fructose these are the most common sugars.
Structure of Monosaccharides
Glucose in common with other hexoses and pentoses easily forms stable ring structure. At any one time most molecules oxists as rings rather than
In case of glucose carbon atom number 1 may combine with the oxygen atom an carbon 5. This form a six -sided structure known as a pyranose ring.
In case of fructose, carbon atom number 2 links with the oxygen an carbon atom number. This form a five sided structure known as furanose ring Both glucose and fructose can exist in beth pyranose ring.
In case of fructose, carbon atom number 2 links with the oxygen on number 5. This form a five sides structure known as furanose ring Both glucose and fructose can exist in both pyranose and furanose
and furanose ring form.
STRUCTURE PG 13 UB
Furanose
Most carbohydrate in common glucose can exists as a numbee of isomers (they posses the same molecular formula but differ in the arrangement of this atoms). one type of isomer called stereo isomerism. occurs when the atom, or group, are joined together but differ in Their arrangement in space one form of stereoisomer is called Optical Isomersm, result in isomer which can rotate the plane of polarized light. If the substance rotates the plane of polarisation to the right it is said to be dexTro-rotatory (d) and if to the left is laevo-rotatory (L) Optical isomerism is a property of any compound which can exist in two forms whose structure are minor image. Like right and left handed gloves
Stady the structure of glycerin (ghycer aldehyde)
L-Form isomer mirror. D-form isomer
Functions of monosaccharides.
PENTOSES (C5H10O5 ) e.g. ribose, deoxyribose, ribulose.
Synthesis of nucleic acids e.g. Ribose is the chief constituent of the RNA.
Synthesis of co-enzymes e.g. ribose synthesis (NAD and NADP)
HEXOSES (C6H12O6) e.g. fructose, glucose, galactose.
Sources of energy when oxidized by respiration.
Synthesis of disaccharides.
Synthesis of polysaccharides.
TRIOSES (C3H6O3) e.g. glyceraldehydes, dihydroxyacetone.
Intermediate in respiration (glycolysis).
Photosynthesis (dark reaction) RUBP as an acceptor of CO2
Carbohydrate metabolism.
*Disaccharides are formed by the condensation or polymerlization of two monosaccharides.
The most common disaccharides are;
Maltose = glucose + glucose
Lactose = glucose + galactose
Sucrose = glucose + fructose.
In reducing sugars e.g. Lactose and maltose, one of the hexose residue retains its aldehyde or ketone groups as an intact unit as reducing sugar.
Maltose is a disaccharide produced upon incomplete hydrolysis of the polysaccharide starch.
It is found in germinating seeds.
It is also produced commercially for use in production of beer.
Maltose is produced of two D-glucose units joined by a α-glycosidic bond between the anomeric carbon of one glucose unit and the number 4 carbon of the other glucose unit.
This specific bond formed an α-1,4-glycosidic bond also found in starch and glycogen.
NB: The numeric hydroxyl group of one of the glucose units participates in the glycosidic bond and
Therefore cannot be easily oxidized.
However the anumeric hydroxyl of the other glucose unit is not as occupied and this glucose unit exists in the equilibrium with free aldehyde solution.
Thus maltose is oxidized by Fehling's solution, benedict's solution or any other suitable reagent.
Constitutes some 3% to 5% of the milk of animal including cows and humans.
This disaccharide is composed of one galactose unit and one glucose unit joined by a glycosidic bond between the anomer of galactose and the number 4 carbon of glucose. A β-1, 4 –glycosidic bond.
Glucose unit of the lactose still exists as an equilibrium mixture of α and β anomers and
the free aldehyde in solution. Lactose is thus a reducing sugar.
It is found in fruits and vegetables.
Sugarcane and sugar beets are the commercial sources and used as table sugar.
Sucrose is composed of one fructose unit joined by two glycosidic bonds.
Sucrose is not a reducing sugar since both anomeric carbons participates in the glycosidic bonds and thus no free aldehyde or ketone exists in solution.
NB: D is the hydroxyl group attached to the anomeric carbon atom (the anomeric hydroxyl group) is drawn on the same side of the ring as the last -CH2OH group for the β-anomer and the opposite side of the ring for the α-anomer.
The D-galactose only differs from the D-glucose only in the orientation of the groups bonded to Carbon no. 4. Ingested D-glucose (from milk and some other complex polysaccharide) is normally converted to D glucose in the human body.
The inability to perform this ionization (conversion of one isomer to another) results in a disease called galactosemis.
Have high molecular weight formed by condensation of large number of monosaccharide units.
They include; Starch, glycogen, cellulose, chitin and insulin.
All polysaccharides are insoluble in water forming colloidal solution.
They are non –reducing sugars.
They are Non- crystalline and as structural materials e.g. Cellulose.
Represented by chemical formula ( C5H10O5) n or (C6H10O5)n where n is a whole number ranging from 300-400.
Usually occur in a white powder-form at room temperature.
It forms a solution with hot water and a gel on cooling.
During digestion, it is converted to a mixture of detrins. Later from maltose to glucose units.
It is largely stored in plants and it is a result of photosynthesis.
In plants, starch is found in the storage parts such as roots and stem tubers, corn and some rhizomes.
A starch granule is composed of
A core of amylase
Amylopeptin
Amyloplast membrane.
Diagrams of amylase and amylopectin.
NB: Amylase and amylopectin are two different forms of starch.
Both have linear chains of glucose units joined by α-1, 4-glycosidic bond.
Amylase is linear polymer of α-1, 4-glucose unit and is insoluble in water.
Amylopectin is a branched polymer; the main chain of amylopectin is joined by α-1,4-glycosidic bond as in amylase. However about every 20-30 glucose units there are branches joined by α-1,6-glycosidic bond.
Amylopectin is not soluble in water.
When boiled to about 2000C starch is partially hydrolyzed to a mixture of dextrins. However, when heated with dilute mineral acids, starch is hydrolyzed via dextrin to glucose.
In living things (tissues) the hydrolysis is of the following sequence.
A suspension of glucose gives a blue black coloration with iodine.
Amylopectin is compact as it has many branches of 1, 6- glycosidic bonds.
Biological importance
Storage of food in seeds, example; cereals and legumes
Important for human food.
This is called animal starch formed by condensation polymerization of glucose on units.
It is very similar to amylopectin in structure.
It is a polymer of glucose units joined by α-1,4- bonds and with α-1,6- bonded branches . it is a white soluble powder and non reducing sugar.
Mainly in vertebrates liver and muscles.
Also some maize seeds and fungi.
Glycogen differs from amylopectin because it is more highly branched than amylopectin with one branch point about every 8 and 12 glucose units.
Biological advantage.
It is important food storage in muscle and liver of vertebrates and fungi.
It provides energy and is an energy substance.
This is an important structural material in plants.
It largely constitutes the chemistry of the cell wall.
Chemically cellulose is composed of several thousands of glucose units joined together by 1, 4- glycosidic bonds. The units are so arranged that the bonds alternate in appearance.
This lead to the cross links of hydrogen bonds between the parallel running cellulose molecules.
As a result of this, cellulose becomes tough with very high tensile strength.
The shape of a cellulose fibre is of the nature below.
Chemical structure of cellulose is presented as follows.
Hydrolysis of cellulose.
In the living tissues, hydrolysis of cellulose takes place in two stages;
Commercial use of cellulose
It is a raw material in the manufacture of many industrial products such as papers, rayon and plastics.
The rayon made from cellulose are used in the manufacture of industrial belts and tyre cords.
Cellulose derivatives such as cellulose nitrate are used in the manufacture of films.
Cotton, a pure form of cellulose is used in the manufacture of clothes.
This is closely related to cellulose in structure and function, being a structural polysaccharide. Structurally it is identical to cellulose except that the OH group at carbon 2 is replaced by – NH.CO. NH3.
This is a result of amino sugar (glucosamine) combine with acetyl group. Chitin is therefore a polymer of N-acetylglucoamine.
This is another storage carbohydrate which largely occurs of many plants. It also occurs in small quantities in many monocots. Hydrolysis by dilute mineral acids or specific enzymes e.g. inulin produce fructose only.
It is a polymer of fructose molecule.
Inulin inulase fructose
Summary roles of carbohydrates.
They built up a cell plasma membrane. It is made up of carbohydrates and so they are used to build up the body of a living organism.
They are used as a substrate in respiration (to produce energy) as raw materials. Glucose is the base raw material in glycolysis.
Are useful in pollination. Nectar which attracts pollinators is made up of sugars.
Are useful in storage purpose for future metabolism eg starch, glycogen and laminarin.
Used in the balance of osmotic pressure as they make solutes in the blood.
Are used in inheritance and control of the body activities as they make the genes e.g. deoxyribose of DNA and ribose of RNA are pentose sugars.
Other uses are from the above discussions.
These are organic compound made up of elements carbon, hydrogen and oxygen in which its proportion of oxygen is smaller than that of hydrogen (i.e. not in the ratio of carbon dioxide of 2:1)
Properties of lipids.
The features that characterize the lipids include the following;
They are either liquids or non-crystalline solids at room temperatures.
They are higher than water ( less dense than water)
They are hydrolyzed by alkaline into their respective constituent compounds. This process is called saponification.
They contain either saturated or unsaturated hydrocarbon chains.
In the presence of water and alcohol they form an emulsion.
They are esters of higher aliphatic alcohols.
All lipids are insoluble in water but soluble in organic compounds or solvents e.g. ether, chloroform and hot alcohol.
They occur in adipose tissues of animals and some are a component of the protoplasm of all living cells.
Lipids have ester linkage.
Because of unsaturated bonds which are easy to break, that are why they are liquid at room temperature, solids contain saturated bonds.
SIMPLE LIPIDS
Simple lipids are oils and fats of which are esters of glycerol. (Higher alcohol). Than glycerol forms the ester called waxes.
Oils and fats are formed by the combination of fatty acids and glycerol e.g. oleic acid which are widely distributed in many fats and oils.
They are also known as triglycerides.
Natural fats and oils.
They are a mixture of glycerides (esters) of fatty acids and glycerol.
Oils: contain greater proportion of unsaturated fatty acids; they are liquid at 200C.
Fats: contain a greater proportion of saturated fatty acids; they are solids at 200C.
BIOLOGICAL IMPORTANCE OF LIPIDS.
They form an insulation material thus prevent heat loss in organisms and animals particularly.
Prevent water loss, form water proof in organisms, plants and insects.
Can be a stored form of energy in the body of an organism e.g. amoeba and seed like units.
Form the basic constituent of the cell membrane as well as the cell components.eg phospholipids
Enables large aquatic organisms like whales to have buoyancy.
Contains basic fat soluble vitamins A, B, D and K.
Forms the natural rubber.
It is a constituent of hormones like steroids e.g. oestrogen, progesterone, also acdysome hormone in insects and crustacea are made up of lipids.
Gives more energy in metabolism.
Used to make bile salts (sodium taurochlorate and sodium glycochorate) for emulsification in the duodenum.
Limits the linkage of small molecules across plasma membrane (cholesterol).
Constituent of myelin sheath; helps to prevent outward flow of ions which would short circuit the movement of ions along the nerve. Also enhance the salutatory condition.
Proteins are nitrogenous compounds formed by condensation polymerization of larger number of amino acids.
Proteins are thus polymer molecules of amino acids.
Element present in proteins are carbon, hydrogen, oxygen, nitrogen, sulphur acid and phosphorous and iron.
THE AMINO ACIDS
There are 20 amino acids which are polymerized to give many types of proteins.
Physical properties.
They are colorless.
They are Crystalline solid.
Form colloidal solution.
Coagulate on – heating
Strong acid or base
Presence of heavy metal
Organic detergent.
They are specific in nature of action.
Substances which are protein in nature are;
Albumin – egg albumin and serum albumin.
Histone – make the chromosome of nucleus.
Globular- blood fibrinogen, prothrombine and antibodies.
Schleroproteins- keratin (of hair and feathers) also keratin of skin, collagen which makes tendon, bone, connective tissue myosin (muscles), silk (spiders web).
GENERAL PROPERTIES OF PROTEINS
They are polymers of amino acids.
Many are large dimmers with many amino acid units. Eg serum globulin of human blood have 736 amino acids, myosin of muscle has 780 amino acids.
Colloidal in nature.
Amphoteric properties.
Every amino acid regardless of its side chain has an acidic carboxylic group and a basic amino group or it has acid-base properties i.e. is said to be amphoteric.
In solid state the amino acid have base salt like properties because they have both a positive charge part and a negative charge part such substances are called zwitterions.
Zwitterions are produced from the molecular form of the amino acid by internal-acid base reaction.
NOTE: in the reaction above, neither the molecular form nor the zwitterions form has a net electrical charge. In aqueous solution these two forms are in equilibrium but the equilibrium overwhelmingly favors the zwitterions at any pH.
At any pH, some of the alamine in solution exists in the positive ion form. Some of it in the negative ion form, some in the zwitterions form and some in molecular form.
If the solution pH is very high that is ( H3O+) or (H+) is very low, both of the equilibrium in the reaction is shifted to form the right and the negative ion form of alamine predomination.
On the other hand, if the solution pH is very low that is (H3O+) 0r (H+) is very high- both equillibria in reaction above are shifted to the left and the positive form of alamine predominates.
At the pH of human cell and fluids (pH7) alanine exists primarily as the zwitterions.
In solution that are predominantly basic (i.e. pH btn 8.5 to 10.5), no single form of alanine predominates. In this pH range, there are roughly comparable amount of zwitterions and the negative charged.
Similarly in moderately acidic solution there are roughly comparable amount of the zwitterions and the positively charged form of alanine.
The amount of positive or negative charge is affected by pH. Each molecule has a specific pH which the total positive charge is exactly equally to the total negative charge. It is electrically neutral and has no tendency to move to either the anode of cathodes of an electric field. This is known as isoelectric point.
At higher pH protein and amino acid become more negative while at low pH they become more positively charged.
Properties of isoelectric point.
Solubility- have greater tendency to precipitate or coagulate.
Stability- as emulsion colloids.
Osmotic pressure- swelling by inhibition of water.
Viscosity and acid and base bonding properties.
They have large size molecule e.g. hemoglobin of mass 6000 and more. The enzyme urease nearly 500,000.
Denaturation – there are easily denatured by heat, ultraviolent reactor and chemicals. Denaturation alters the structure of proteins.
Structure of amino acids.
The amino acid consists of an α carbon surrounded by;
Hydrogen atom(H)
Amino group or amine group (-NH2), giving the nature of amino acid.
The carboxyl (-COOH) giving the acidic nature of amino acid.
The R-group known as the side chain. It presents the hydrogen atom or any other group as alkyl group.
How peptide bonds are formed.
Proteins are polymers of amino acids joined together by peptide bond.
OTHER BONDS FOUND IN PROTEINS.
Ionic bonds: is an electrostatic attraction between positive and negative charge.
Hydrogen bond: this occurs between hydrogen atom and more electronegative atoms.
Disulphide bond: the bond between two crystalline molecules.
Van-de-Waal forces: these are weak non-attraction forces (hydrophobic interactions) created between –CH3 groups which are non-polar.
CLASSIFICATION OF PROTEINS.
Level of organization.
According to function.
According to composition.
To whether they contain essential amino acids.
According to structure.
ACCORDING TO LEVEL OR ORGANISATION.
Primary structure.
Secondary structure.
Tertiary structure.
Quaternary structure.
This is a linear sequence of amino acids joined together by peptide bonds. Also disulphide bond may be found.
This is due to coiling or twisting of the polypeptide.
α helical
This is due to attraction of various amino acids. This is a component of hair, claws, nails, as well as skin.
β pleated sheets (zig zag structures)
Collagen is a compound of tissues like bones and cartilage. Collagen is an example of β pleated sheets.
Tertiary structure is due to coiling and twisting of the polypeptide helix forming a globular or spherical shape.
Bonds present in the coiled structure are ionic bond, hydrogen bonds, hydrophobic interactions, disulphide bridges.
Examples of tertiary structures. (They are very soluble).
Immune globin( antibodies)
Homornes
Quaternary structure is due to coiling and twisting of various polypeptide chains usually the structure is associated with non-protein parts called prosthetic groups e.g. hemoglobin.
Hemoglobin has four polypeptide chains, two α-chains and two β chains each surrounding an iron atom.
The hemoglobin consists of protein parts. The protein part consist of 4 polypeptide chains, of the four polypeptide chains, 2α chains and 2 β chains and is called globin. The non protein parts is called HAEM consist of poiphyding surrounding an iron atom.
THE FOUR LEVELS OF PROTEIN STRUCTURE
ii. BASED ON WHETHER THEY CONTAIN ESSENTIAL OR NON ESSENTIAL AMINO ACIDS.
Essential amino acids Vs non essential amino acids
Essential amino acids are those which cannot be synthesized by human cells but are obtained from food.
All of the 20 α amino acids are needed to make different proteins in the body of a human.
Twelve of these amino acids can be synthesized by the cells from other substances that are present in the body; these are called non-essential amino acids.
The other eight cannot be synthesized by the body and must be included in the persons diet are called essential amino acids.
iii. BASED ON COMPOSITION.
Simple proteins
Simple proteins are made up of amino acids only.
E.g. – Histones (nucleoprotein)
Globulin( immunoglobulin)
Schleroproteins ( e.g. Keratin)
Albumins
Pastamins
Conjugated proteins.
Made up of amino acids; are globular proteins associated with non protein materials. E.g. haemoglobin glycoprotein (components of cell membrane), mucin (component of saliva), lipoproteins (components of cell membrane).
iv. ACCORDING TO FUNCTION.
NOTE:these are also functions proteins.
TYPE EXAMPLE OCCURRENCE/ FUNCTION.
Viral coat protein
Components of the connective tissue, bone, tendon,cartilage, skin,hair,feather, nails and horns.
Elastic connective tissues (ligaments 'wraps up' nucleic acid for virus.
Trypsin.
Ribulose biphosphate carboxylase.
Glutamine synthesase.
Catalyze hydrolysis of proteins
Catalyses carboxylation (oxidation) CO2 of ribulase biphosphate in photosynthesis.
Catalyze synthesis of amino acids, glutamine from glutamic acid and ammonia.
Adrenaline corticotrophic hormone (ACTH).
Helps to regulate glucose metabolism.
Stimulates growth and activity of the adrenal cortex.
Respiratory pigment.
Transports oxygen in vertebrate's blood.
Stores O2 in muscles.
Transports fatty acids and lipids in the blood.
Fibrinogen
Form complexes with foreign proteins
Form fibrin in blood clotting
Involved in blood clotting mechanism.
Contractile
Moving filaments in myofibrils of muscles
Stationary filaments in m myofibrils in muscles.
Ovalbumin
Toxin made by diphtheria bacteria.
NEUTRAL AMINO ACIDS.
This is because their side chains have no charge at the pH of body cell. Thus are divided into;-
Natural hydrophobic amino acids.
Natural hydrophilic amino acids.
Seven natural amino acids have side chains(R) that are non polar or hydrophobic. These hydrophobic are either alkyl or aromatic in nature.
Alanine (ala).
Valine (Val).
Leusine (leu).
Iso leusine.
Phenyl donine (phe)
Tryptophan (trp).
Neutral hydrophilic amino acids.
Eight amino acids are classified as hydrophilic.
In general these amino acids are more soluble than hydrophobic amino acids.
The acid chain of glycine (gly) is just hydrogen. The other seven neutral hydrophilic amino acids have side chains that can form either strong or weak hydrogen bond with water.
These have hydroxyl group in either side chain serine (ser) theorine (Thr) or tyrosine (try). Two contain an amino functional group, asparagines (asp) and glutamine (gln). The remaining two contain a sulphur atom cysterine (cys) and methionine (met).
Others include: tyrosine, asparagines, cysterine, glutamine, and methionine.
ACIDIC AMINO ACIDS
Acidic amino acids have side chains that contain a second carbonyl group.
At the pH of cells in the body, these carboxylic groups exist primarily as negative charged carboxylate ions and this interact strongly with water molecules.
Aspartic acid (asp)
Glutamic acid (glu)
BASIC AMINO ACIDS.
Three of the amino acids contain a side chain that act as a proton acceptor or base. They are thus classified as basic amino acids, these are lysine (lys), arginine (arg) and histamine.
v. BASED ON STRUCTURE
a. fibrous protein.
Have a secondary structure and little or no tertiary structure.
Insoluble in water.
Physically tough.
Form long polypeptide chain cross linked at intervals forming long fibres or sheets.
Functions of fibrous proteins.
Perform structural function in cell and organism e.g. collagen (tendon, bones, connective tissues) myosin in muscles, (silk) spider web, keratin (nail, hair, feathers).
b. globular proteins.
Found mostly in tertiary structure.
Polypeptide chain highly folded to form spherical shape.
Easily soluble in water.
Functions of globular proteins.
Forms enzymes, antibodies and some hormone e.g. insulin.
c. intermediate protein.
Fibrous in nature but soluble in water e.g. fibrinogen.
Function of intermediate protein.
Fibrinogen forms insoluble fibrin when blood clots.
Like proteins, nucleic acids are largely polymers made up of small number of different building blocks called nucleotides.
Each nucleotide is in turn composed of 3 smaller parts.
A phosphate group.
Monosaccharide
A nitrogen containing base.
The term nucleotide is used to refer to nitrogenous base bound to a monosaccharides. And the nucleotide is a nucleotide phosphate.
There are two major types of nucleic acids.
deoxyribose nucleic acids (DNA).
ribonucleic acid (RNA).
There are two main differences between the deoxyribonucleotide components of DNA and the ribonucleotide component of RNA.
Criterion DNA RNA
Sugar component
– Has its sugar D-ribose lacking hydroxyl group in carbon #2 of ribose; hence the prefix De-oxy is used to denote the absence of oxygen at that position. – Has its sugar D-ribose having oxygen at carbon number 2.
Organic bases.
– Have four possible organic bases, 3 of which are adenine, guamine and cytosine and the fourth is thymine which is lacking in RNA. – Have four possible organic bases, 3 of which are adenine, guamine and cytosine and the fourth is uracil which is lacking in DNA.
JOINING THE NUCLEOTIDES TO FORM A POLYMER OF DNA OR RNA.
The bond that holds these polymers together are ester linkage formed between the phosphate on the number 5 carbon of ribose in one nucleotide and the hydroxyl on the number 3 carbon of ribose in the next nucleotide (deoxyribose in the case of DNA)
Two nucleic acids are said to have 3l5l– phosphate ester bridge/bond between their nucleotide components
Diagram of a long nucleic acid.
The DNA consists of two long polynucleotide strands and the base components of each nucleotide on one strong can form hydrogen bonds with only one specific nucleotide base on the other strand.
Guamine (G) can hydrogen bond only to cytosine in another DNA strands form a base pair.
Adenine (A) can hydrogen bond with thymine (T).
ATP (ADENINE TRIPHOSPHATE)
ATP is formed from the nucleotide adenosine monophosphate by the addition of two further phosphate molecules.
Its structure:
ATP is an energy store, because the last branches are highly energetic on breaking.
The hydrolysis of ATP to ADP is catalyzed by the enzyme ATPase and the removal of the terminal phosphate yield 30.6kj mol-1 of free energy. So does the second one to from ADP and AMP respectively. AMP and ADP may be re-converted to ATP by the addition of phosphate molecule in a process called phosphorylation of which there two main forms.
Photosynthetic phosphorylation– occurring during photosynthesis in chlorophyll-containing cells.
Oxidative phosphorylation – occurring during cellular respiration in all aerobic cells.
USES OF ATP.
A metabolic active cell may require up to two million ATP molecules every second. ATP is the source of energy for;
Anabolic processes. It provides the energy needed to build up macromolecules from components units.
Polysaccharide synthesis from monosaccharide.
Protein synthesize from amino acids.
DNA replication.
Movement- it provides the energy for many forms of cellular movements, including;
Muscle contraction
Cilliary actioning
Spindle action in cell division.
Active transport – it provides the energy necessary to move materials against concentration gradient e.g. ion pumps.
Secretion – it is secreted to form the vesicle in the secretions of the cell product.
Activation of chemicals – it makes chemicals more enabling them in reacting (more readily) e.g. the phosphorylation of glucose at the start of glycolysis.
Enzymes are simple or compound organic proteins which are organic catalysts catalyzing reactions in living tissues.
ENZYME: Greek word "en" means in and "zyme" means yeast cell.
They are bio catalysts found in living things.
Catalysts accelerate chemical reactions although a catalyst is a participant in a reaction and undergoes physical change during the reaction. It reverts to its original state when the reaction is complete.
Enzymes are protein catalysts for chemical reactions in biological systems. Most chemical reactions of living cells would occur very slowly, were it not for catalyzing enzymes as illustrated below.
Energy diagram under catalyst action showing progress of the reaction.
Fig. reduction of necessary activation energy by enzymes.
NB: as seen in the above graph, the activation energy (Ea) necessary to initiate the reaction is much less in the presence of the catalyst than in its absence.
It is this lowering of activation energy barrier by enzyme catalysts that makes possible most of the chemical reactions in life.
By contrast to non-protein catalyst (e.g. H+, OH –, or metal ions) each enzyme catalyze a small number of reactions, frequently only one and thus enzymes are reaction –specific catalysts.
Most inorganic catalysts are relatively non specific for example platinum, often used to catalyze the formation of water from hydrogen gas and oxygen gas. Will catalyze almost any reaction in which H2 is one of the reactants and the reaction of materials as well.
Properties of enzymes.
They generally work fast than inorganic catalysts and greatly lower the activation energy.
Enzymes are not consumed by the reaction they catalyze i.e. a given molecule of an enzyme can be used indefinitely if the conditions are kept suitable.
Enzymes can work in either direction i.e. catalyze reversible reactions. This is due to the fact that metabolic reactions are reversible and the direction of the reaction depends on the relative amount of substrates and products present.
Enzymes are denatured by excess heat (temperature) by the virtue of their proteineous nature.
Enzymes are sensitive to pH. Every enzyme has its own range of pH at which it functions effectively.
Enzymes are specific in the action they catalyze. Normally a given enzyme will catalyze only one reaction or one type of reaction.
Enzymes react in only small amount. A very small amount of catalyst will transfer in a very large amount of reactants.
They are colloidal in nature and thus provide large surface area for reaction to take place.
Enzyme activity can be accelerated or inhibited. The accelerators are called activators e.g. Cu, Zn, Co, Cl, Ca. while the inhibitors are for example DOT, Pb, and Hg etc.
NATURE AND MODES OF ENZYME ACTIVITY.
Hypothesis explains the nature and mode of enzyme activity.
The lock and key theory (hypothesis) by Fischer.
In the model the three dimensional configuration of the enzyme represented the lock (the active title) into which particular substrate (key) will fit.
The active site presumes to be rigid.
The induced fit model by Koshland.
Originally little more than an attractive hypothesis, this model now has received considerable experiment support.
An essential feature is the flexibility of the region of the active site. In this mode, the substrate induce the conformation change in an enzyme just like the shape of a glove is affected hand wearing.
MOLECULAR STRUCTURE OF ENZYMES.
Enzymes are either composed of;
Protein alone-simple enzymes.
Protein and other non-protein molecule( i.e. conjugated enzymes)
The protein part of an enzyme is called Apanzyme.
Non- protein part is called co-enzyme.
The protein part of an enzyme is made up of enzyme protein zymoprotein.
The two component (the apoenzyme and coenzymes) make up the active enzymes called holloenzymes.
Holoenzymes = coenzyme + apoenzyme.
Prosthetic groups are usually metallic ions such as Co, Mg, Ni, Cu, Zn (mineral salt). This is also a non-protein part, the well known co-enzyme are those which function as hydrogen carriers, in-oxidation-reduction in energy metabolism. For instance coenzyme NAD, NADP, Q, A. Coenzyme A is involved in transfer of an acetyl group.
These are substances which increase the activity of the halo enzymes. Their absence may retard the catalytic activity of the enzymes or preventing it from acting.
Activators are usually inorganic ions e.g. Ca2+ for thrombo kinase, Cl– for ptyalin, Mg2+ for phosphate.
Coenzymes and activators are needed by the enzymes for proper activities.
FACTORS AFFECTING ENZYMATIC ACTIVITY.
Over a limited range of temperature, the velocity of enzyme catalyzed reactions increase as the temperature rises. The exact ratio by which the velocity change for a 100C temperature rise is the Q10 or temperature coefficient.
The velocity of many biological reactions roughly doubles with a 100C rise in temperature ( Q10 = 2) and is halved if the temperature is decreased by 100C. Many physiological processes e.g. the rate of contraction of an exercised heart- consequently exhibit Q10 of about 2.
When the rate of enzyme catalyzed reaction is measured at several temperature the result shows in the figure below is typical. There is an optimal temperature which the reaction is most rapid. Above this reaction the rate decrease sharply due to heat denaturation of the enzyme and below this the energy content of enzymes is too low to make them participate in their reaction.
Fig. enzymes activity as a function of temperature.
Although temperature sensitivity varies somewhat from one enzyme to another the curve shown here may be taken as applying to an average enzyme.
Its activity rises steadily with temperature (approximately) doubling for each 100C increase until thermal denaturation cause a sudden sharp decline, beginning between 400C and 450C. The enzyme because completely ineffective/ inactive at temperature above 600C presumably because its three dimensional configuration has been severely disrupted.
Denaturation of a protein enzyme by heat is the loss of it biological activity. This can be done also by heat, acid or high salt concentration.
2. pH.
Moderate pH changes affect the ionic state of the enzyme and frequently that of the substrate also.
When enzyme activity is measured as several pH values optimal activity is generally observed between pH values of 5 and 9. However the few enzymes eg pepsin is active at pH values well outside this range. The shape of pH activity curves is determined by the following factors.
Enzyme denaturation.
At extremely high or low pH values.
Since the only forms that will interact are SH+ and E–. Extreme pH values will lower the effective concentrations of E– and SH+ thus lowering the reaction velocity as shown below.
Only the crossed-hatched area of S and E in the appropriate ionic state and thermal concentration of E and S are correctly charged at X the result is a bell-shaped pH activity curve
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redpajama_set_name: RedPajamaCommonCrawl


Samsung is gearing it for its launch of the year, with the Galaxy S3 set to debut its slinky self on Thursday in London. Check out our full Galaxy S3 launch coverage for the latest news as it happens!
Here's your handy guide to everything we know so far.
Samsung has teased us for months, dangling the new Galaxy before us like a delectable carrot before yanking it just out of reach. There hasn't been this much speculation, anticipation and leaks over a mobile outside of the iPhone, including the hoisting then hasty yanking of pre-order pages, networks scrambling to announce future availability, and of course, the mystery over what it's actually called ('the next Galaxy' is all official press releases will allow).
The Galaxy S II is an incredible phone, combining a crisp, beautiful screen with powerful components and cramming it all into a light, slender package. We're sure the S3 (or SIII, or maybe New Galaxy) will be a worthy follow-up, if the rumoured 10 million pre-orders are anything to go by.
Original whisperings from weeks ago had it packing a 1.5GHz quad-core Exynor processor and a 4.65-inch Super AMOLED HD screen that will take on the iPhone 4S's Retina display in sharpness and pixel density. A 720x1280-pixel resolution was anticipated. We were also expecting at least a 12-megapixel camera with LED flash, and some exciting features to rival HTC's One phones. NFC support and Android Ice Cream Sandwich are pretty much a given.
Then just over a week ago, Amazon 's German site made a blunder by posting Galaxy S III details prematurely. The Amazon breakdown gives the phone a 4.7-inch Super AMOLED display, as opposed to the 4.65-inch Super AMOLED Plus screen previously rumoured. The 12-megapixel camera listed here matches the one we expected, as does the Android Ice Cream Sandwich OS.
The official launch is 3 May, so we're expecting the phone to hit stores over summer, with June being a safe bet. We'll be reporting live from the event, so check back here for full info and pics as we get them.
You can also follow us on Twitter to get our thoughts as it all kicks off!


Fortinet leads the way of training and education in the company's ongoing efforts to bridge the cybersecurity skills gap by rolling out further expanded training and education initiatives.
The latest addition to the company's education and training programming includes additional Fortinet Network Security Expert (NSE) Institute cloud certifications.
While the NSE Training and Certification program has already issued nearly 200,000 certifications, it remains equally focused on education programs such as the Fortinet Network Security Academy program for high schools, colleges and universities, the FortiVets program that facilitates the transition of exceptional military veterans into the cybersecurity industry by providing professional networking, training, and mentoring alongside, a free publicly available awareness training that can be accessed by any company wishing to deploy an internal cybersecurity awareness program for employees.


text:
<?php

namespace toy\factories;

use \toy;

/**
 * Class JsonResponse
 *
 * @author Nauris Dambis <nauris.renarti@gmail.com>
 * @version 1.0
 *
 */
class JsonResponse
{
	/**
	 *
	 * @var array
	 */
	private $_data = array();

	/**
	 *
	 * @var int
	 */
	private $_options = 0;

	/**
	 *
	 * @param mixed $data Array or Object
	 */
	public function __construct($data = array(), $options = 0)
	{
		header('Content-Type: application/json');
		$this->setOptions($options);
		$this->setData($data);
	}

	/**
	 *
	 * @param int $value
	 * @return \toy\factories\JsonResponse
	 */
	public function setOptions($value)
	{
		$this->_options = $value;
		return $this;
	}

	/**
	 *
	 * @param mixed $value
	 * @return \toy\factories\JsonResponse
	 */
	public function setData($value)
	{
		$this->_data = $value;
		return $this;
	}

	/**
	 *
	 */
	public function write()
	{
		print json_encode($this->_data, $this->_options);
	}

}

/* End of file JsonResponse.php */
/* Location: ./modules/toy/factories/JsonResponse.php */

redpajama_set_name: RedPajamaGithub