Question

Multiple choice questions. Please highlight, circle answers, or make them obvious when displayed alongside explanations.

10. (5 pts) The antibiotic erythromycin disrupts protein synthesis by preventing ribosomal translocation (movement of the ribosome relative to the mRNA). It does not affect any other step in protein synthesis. Suppose you are doing a translation reaction in vitro and you add erythromycin just before the 3rd peptide bond is about to be made. You wait a few minutes and look at the ribosome.

Circle the correct answer:

1. The carboxyl end of AA #3 should now be covalently bonded directly to:

(tRNA #2) (tRNA #3) (tRNA #4) (AA #2) (AA #3) (AA #4) (none of these).

2. Which tRNA will you find in the A site?

(tRNA #1) (tRNA #2) (tRNA #3) (tRNA #4) (tRNA #5).

3. The tRNA in the A site will carry:

(an amino acid) (a polypeptide) (neither) (either one)

Answer 1

9 ca The carboxylic end of the AA #3 Should now be covalently directly bonded to the AA#4, because the process of Peptide bond formation doesn't inhibited by the erythromycin. Exy thromycin inhibits the mRNA translocation along the ribosome (6) We will find the ARNA #3 in the A-site. After carrying the third amino acid the ARNA #3 will attach to the A-site. The third amino acid will form a peptide bond in p. site with growing Polypeptide and the bonded will then transferred to the A site. The ARNA in the A-site will always carry an amino acid, and the and the tRNA in the p-site will carry the polypeptide.