Chapter
4: PROTEIN SYNTHESIS
Use of RNAs in protein synthesis:
- mRNAs
contain the code of the primary protein sequence (4-21); features of the
genetic code, the codon for initiating methionine (AUG) and stop codons
(UAG, UGA, UAA) (T4-2).
- tRNAs
match a specific amino acid to a codon; tRNA structure (4-26); wobble
bases reduce the number of tRNAs needed to decode 61 codons (4-27);
aminoacyl tRNA synthetases match the amino acid to the appropriate tRNA
(4-29).
- Ribosomal
RNAs form a structural scaffold for the small and large and small subunits
of the ribosome (4-32); the ribosome functions with the other RNAs to
synthesize proteins using the enzyme peptidyl transferase.
The formation of proteins on ribosomes:
- Initiation
of translation at the AUG codon (i.e. forming initiation complex on small
subunit, scanning for Kozak sequence, adding the large subunit) (4-37).
- Elongation
of the peptide (bringing amino acids into the A site by EFs, adding the
peptide chain to the incoming amino acid via peptidyl transferase,
movement of the peptide containing tRNA from the A site to the P site)
(4-39).
- Termination
using release factors (4-40).