Question

Imagine you are following a particular tRNA, called tRNAQ, through the process of translation in a eukaryote. In what order does tRNAQ go through the steps listed? Note that some steps may be used more than once. 1. The polypeptide is transferred to tRNAQ. 2. tRNAQ binds the A site of the ribosome. 3. tRNAQ binds the P site of the ribosome. 4. The ribosome shifts, with tRNAQ still bound. 5. tRNAQ binds the E site of the ribosome.

Answer 1

Answer:

2. tRNAQ binds the A site of the ribosome.

1. The polypeptide is transferred to tRNAQ.

4. The ribosome shifts, with tRNAQ still bound.

3. tRNAQ binds the P site of the ribosome.

4. The ribosome shifts, with tRNAQ still bound.

5. tRNAQ binds the E site of the ribosome.

Explanation:

tRNAQ first lands on the A site of the ribosome. It carries an amino acid according to the exposed codon on A site. A bond is formed between the amino acid of A and P site such that the polypeptide is transferred to tRNAQ. The ribosome shifts now and tRNA Q moves to P site from A site while still bound to mRNA. Another tRNA enters the A site and the above process is repeated which finally transfers the polypeptide chain from tRNAQ to new tRNA. tRNAQ has no attached polypeptide now and is ready to leave the translation complex. The ribosome shifts again with the tRNAQ still bound to mRNA. tRNAQ enters the E site from P site and finally leaves the translation complex by exiting the E site.