Enzymes are not destroyed by the reactions which that catalyse Since enzymes are not altered by the reactions they catalysed, they can be used again.
The enzyme Biology form 4 chapter 4 essay question then encapsulated in a transport vesicle. Small changes in the pH of the medium will denature the enzyme and render its activity.
For example, catalyse can transform approximately six million hydrogen peroxide molecules into oxygen and water molecules per minute. As temperature rises, its activity increases until the optimum temperature is reached.
For example, pepsin rennin, ptyalin and trypsin. When the enzyme synthesis has completed, it is extruded into the interior of the endoplasmic reticulum. Without enzymes, these biochemical reactions would be too slow to sustain life.
Intracellular and extracellular enzymes Enzymes can be divided into two groups: Enzymes work very rapidly One molecule of enzyme can turn thousands or millions of substrate molecules into products per minute.
In the Golgi apparatus the enzyme is further modified before packing the enzyme in a secretory vesicle. A smaill concentration of enzymes can bring about a large amount of biochemical reactions 3.
Various types of bonds including hydrogen bonds and ionic bonds hold the substrate s in the active site to form a enzyme-substrate complex. This is because enzymes are made of protein, so they are denatured at high temperature.
Deviations from the optimum pH decrease the rate of reaction because bonds maintaining the tertiary shape of the enzyme are broken. The secretory vesicle transports the enzyme to the plasma membrane.
Mechanism of enzyme action Each enzyme molecule has a region with very precise shape called the active site. General characteristics of enzymes 1. The substrate molecule fits into the active site of the enzyme like a key into a lock.
Enzymes are proteins which act as biological catalysts. The transport vesicle fuses with the Golgi apparatus, releasing the enzyme into the Golgi apparatus. Enzymes formed and retained in the cell are known as intracellular enzymes, and occur in the cytoplasm, organelles or the nucleus.
Enzymes are sensitive to pH Every enzymes has its own optimum pH in which it functions best. Most digestive enzymes are extracellular enzymes.
Note the two way arrows. For example, maltase acts on maltose, sucrase on sucrose and cellulase on cellulose. The enzyme is denatured. As more active sites are available, more substrates can be converted to products.
Temperature Initially an increase in temperature leads to an increase in the rate of reaction because the kinetic energy of the enzyme and substrate molecules produce more collisions, and therefore more enzyme-substrate complexes are formed.
For example, amylase, cellulase and zymase. The substance whose reactivity is increased by an enzyme is known as substrate. Enzymes are denatured by high temperature An enzyme inactive at very low temperature. The instruction for making the extracellular enzyme is transcribes from deoxyribonucleic acid DNA to ribonucleic acid RNA in the nucleus.
They speed up biochemical reactions in the cell. Eventually all the active sites are filled at any one time and the rate remains constant The reaction has reached its maximum rate, Vmax.
Extracellular enzymes are produced in the cell then packed and secreted from the cell, Extracellular enzymes caralyse their reactions outside the cell. After the optimum temperature, the rate of reaction falls quickly because the bonds maintaining the structure of the enzyme start to break and the active site loses its shape.
The enzyme then changes the substrate s either by splitting it apart for example, hydrolysis or linking them together for example, condensation Once formed, the products no longer fit into the active site and escape into the surrounding medium, leaving the active site free to receive further substrate molecules.
The rate of reaction will increase up to a maximum, known as the optimum temperature. Further addition of substrate will not increase the rate of reaction anymore because the constant enzyme concentration becomes the limiting factor. The active site loses its shape and the enzyme-substrate complex can no longer be formed.
Factors afftecting enzymes 1. Enzyme Concentration As the concentration of the enzyme increases there are more chances of enzyme-substrate collisions. Alterations in the ionic charges of the acidic and basic groups of the enzyme change the shape of the enzyme.A complete BIOLOGY SPM exam focus,marking scheme included.
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Posts about Chapter 4: Chemical Composition of the Cell written by 5 people. Biology for Life. Home; About; in the active site to form a enzyme-substrate complex. With that in mind, how do we know if something is living?What are the characteristics of life?
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