Translation Flashcards
What components does translation require?
mRNA, aminoacyl-transfer RNA and ribosomes.
What does degenerate mean?
More than one triplet code may code for the same amino acid.
What is the role of tRNA in the process?
It acts as a shuttle to link amino acids to the nucleic acid. Each tRNA molecule has a different anticodon.
What does it mean when the tRNA is charged/coupled?
When the correct amino acids is covalently attached to the tRNA, specified by the anticodon.
How do aminoacyl-tRNA synthases select the correct tRNA to be acylated?
They recognise specific tRNA identifiers present on the acceptor step and anticodon loop.
Where does protein synthesis occur?
In ribosomes.
In what conditions do the two subunits of ribosomes combine?
In the presence of mRNA and a charged tRNA molecule.
What are the three main steps of polypeptide synthesis?
Chain initiation, chain elongation and chain termination.
What is the first step in chain initiation?
The formation of the 43S pre-initiation complex from the combination of 40S-EIF3 and EIF2.
How is the initiation complex formed?
The cap binding of mRNA to the 43S pre-initiation complex.
What happens are the formation of the initiation complex?
It unwinds the mRNA using the EIf4 helicase and stops at the start site AUG. No further unwinding can occur due to an irreversible GTP hydrolysis.
How is the P site formed?
The association of the 60S-EIF6 due to the GTP hydrolysis.
What is the first step of chain elongation?
Charged tRNA (aatRNA) binds to an A site on the ribosome by base pairing with a codon.
What is the second step of chain elongation?
Conformation change in the ribosome which is induced by GTP hydrolysis of EF1a.
What is transpeptidation?
The third step in chain elongation and is when the C terminal of the polypeptide is uncoupled from the P site tRNA and the peptide bond is transferred to an amino acid on the A site tRNA, which is cataylsed by peptidyltransferase.
