3. To study bacterial ribosomes, researchers make use of antibiotics that inhibi

Question

3. To study bacterial ribosomes, researchers make use of antibiotics that inhibit ribosome function at different steps of translation. What would be present (uncharged-tRNA, amino acyl-tRNA, peptidyl-tRNA, et...)jin the A and P sites of an elongating prokaryotic ribosome when the following antibiotics are present a. Tetracycline: binds in the A site a blocks entry of amino-acyl tRNA to the A site of ribosome. previous tFVA tiniticrtun tRNA) n P sit b. Kanamyocin: prevents translocation c. Kirromycin: prevents release of EF-Tu/GDP from aa-tRNA. d. Puromycin: can bind the ribosome peptidyl transfer active site and accept the growing peptide chain. e. Ricin: cleaves the rRNA, which inactivates its GAP function.

Explanation / Answer

a. It blocks only the entry of aminoacyl-tRNA. So P-site will not be affected.

P-site: Peptidyl-tRNA A-site: Nothing

b. Once the peptidyl chain is transferred to the aminoacyl-tRNA, the new peptidyl-tRNA is translocated to the E-site from P-site. Blockage of translocation leads to retaining of peptidyl-tRNA in P-site.

P-site: Peptidyl-tRNA A-site: Aminoacyl-tRNA

c. EF-Tu/GDP must be released in order to attach aminoacyl-tRNA to the A-site. If EF-Tu/GDP is not released, aminoacyl-tRNA is not attached to the A-site.

P-site: Aminoacyl-tRNA A-site: Nothing

d. Puromycin binds to the A-site and attached to the peptidyl chain in P-site. But further addition of amino acid is prevented.

P-site: Peptidyl-tRNA with puromycin A-site: Aminoacyl-tRNA

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.