Translation-Synthesis of Proteins
Biochemistry-Free Online lessons by Biochemistry club
The process of protein synthesis occurs in 3 stages:
- Elongation, and
Special protein factors for Initiation
- Initiation Factor (IF)
- Elongation (EF) and
- Termination (release factors), as well as
- are required for each stage
- In the first step, the small ribosomal subunit binds to the mRNA.
- In Prokaryotes, the 16S rRNA of the small subunit binds to the Shine-Dalgarno sequence in the 5′ untranslated region(UTR) of the mRNA.
- In Eukaryotes, the small subunit binds to the 5′ cap structure and slides down the message to the first AUG.
- The charged initiator tRNA becomes bound to the AUG start codon on the mRNA through base pairing with its anticodon.
- The initiator tRNA in Prokaryotes carries fMet, whereas the initiator tRNA in Eukaryotes carries Met.
- The large subunit binds to the small subunit, forming the completed initiation complex.
- There are 2 important binding sites on the ribosome called the
P site (peptidyl site) & the A site (aminoacyl site)
- The P site is the site on the ribosome where fMet–tRNAi initially binds.
- After formation of the first peptide bond, the P site is a binding site for the growing peptide chain.
- The A site binds each new incoming tRNA molecule carrying an activated amino acid.
- Elongation is a 3-step cycle that is repeated for each amino acid added to the protein after the initiator Methionine.
- Each cycle uses 4 high-energy bonds (2 from the ATP used in…
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