Question

(1) Briefly explain why no energy is expended at the moment of peptide bond formation during protein synthesis.

(2) You discover a new antibiotic that specifically acts to inhibit peptide bond formation but does not affect any steps before that. What specific part of the ribosome (name it) would this inhibitor most likely affect DIRECTLY?

(3) During translation translocation, it can be said that a peptidyl tRNA moves to the P site and a deacylated tRNA moves to the E site. BRIEFLY explain how this happens.

Answer 1

1. The step in protein synthesis involves amino acid getting connected to each other without any energy input. This is because the amino acid that is about to get joined are being activated prior to joining. Such an activated amino acid is energetically favourable than an isolated amino acid. This activation is achieved by formation of charged aminocyl-t RNA's. This amino acid is attached to the matching tRNA by hydrolysis process forming an ester bond. Then ribosome is used by aminocyl-tRNA displacing the previous tRNA and adds the growing peptide to the aminnon acid. Like this an ester bond is broken and a peptide bond is formed.

2. the subunits of ribosomes are 30s , 70s and 50s ribosomes

3- translation is initiated in the 30s subunit with the help of initiation factors to the ribosomal P site where it recognozes the start coon of the mRNA is present. The 50s subunits assosciate with 30s forming 70s initiation complex which is responsible for the elongatioin of the protein.