Flashcards in Biochem 6 translation Deck (22):
the essential components for translation are
ribosomes, mRNA, tRNA, aminacyel tRNA synthetase
Components of Eukaryotic ribosomes
a 60s and 40s subunits
What are UTRs
untranslated regions of mRNA that flank the coding sequence. They help determine the stability of the message and signal how long the mRNA should be around
synthesized by pol III, has a cloverleaf structure. The RTNA has an anticodon loop that interacts with mRNA codon. Also has a CAA terminus, where the AA is connected
tRNA post translational modifications
addition of CCA sequence on 3' end, modification of "unusual bases"
specific for each AA, matches tRNA CAA end to AA and links, using ATP
relaxed bonding between the 3' base of codon and 5' base of anticodon
1.Met-tRNA binds eIF2 and GTP, then binds 40s subunit
2. eIF4 recognizes cap on mRNA
3. Complex scans migrate 5-3 to find AUG start codon
4. At start codon, eIF2 is released and 60s subunit can bind
what does eIF2 recognize during translantion?
the cap on mRNA
What are the three sites in the large subunit that interact with tRNA?
A (accepts new tRNA), P (peptide linked tRNA) , E (exit) sites
chaperones tRNA to A site, catalyzes GTP
move tRNA from A site to P site and E site, uses eEF2
component of 28s RNA, forms peptide bond
requires stop codon and termination factor, which binds to stop codon in A site and allows the protein to be released
multiple ribosomes translating same mRNA, increases rate of protein output
3 types of translation errors
one base change, results in AA error. This can have several consequences, including changing splice sites and deleting a stop codon (larger protein product)
new stop codon, resulting in smaller protein
Frame shift mutation
a deletion or addition of a base. Changes every subsequent AA, can be serious
regulates translation. When phosphorylated, it is inactive and cannot start translation
internal ribosome entry sites used by Viruses to recruit pre initiation complex without cap/ initial scan.