CSIR NET Genes and Proteins — practice questions — page 3

1. The A site is where incoming charged aminoacyl tRNAs bind. 2. Blocking that site therefore stops tRNAs from binding to the ribosome. 3. With no tRNA delivered, no codon after the start can be read and elongation never gets going. 4. Chloramphenicol is the drug that blocks peptidyl transfer, so growth of the chain is the effect of that antibiotic instead. 5. Subunit assembly happens before the A site is used, so it proceeds unhindered. 6. Termination needs a chain to release, so it is never reached rather than being the step blocked. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 15 "Genes and Proteins", section 15.5 Ribosomes and Protein Synthesis_

1. The E. coli translation apparatus takes only 0.05 seconds to add each amino acid. 2. Multiplying that by 200 residues gives 10 seconds for a 200-amino acid protein. 3. Checking the arithmetic rules out the neighbouring values, since 0.5 seconds each would need 100 seconds for that protein. 4. At 0.005 seconds each the same protein would take only one second, which is faster than the stated figure. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 15 "Genes and Proteins", section 15.5 Ribosomes and Protein Synthesis_