As a ribosome translocates along an mrna molecule by one codon, which of the following occurs?

As a ribosome translocates along an mrna molecule by one codon, which of the following occurs? the trna that was in the a site moves into the p site. the trna that was in the p site moves into the a site. the trna that was in the p site moves to the e site and is released. the trna that was in the a site departs from the ribosome both a and care correct.

Answers

The tRNA that was in the A site moves into the P Site, and the tRNA that was in the P site moves to the E site and is released.

e. The tRNA that was in the A site moves into the P site.

Explanation:

Translation comprises 3 steps :

1) Translation initiation

2) Translation elongation

3) Translation termination

Translocation step is a part of translation elongation step which is followed by the peptidyl transferase activity of ribosome. Due to the peptidyl transferase activity of ribosome, the N terminal of newly entered amino acid (amino acid attached with tRNA i.e. aminoacyl tRNA or charged tRNA) at 'A site' attacks the C terminus of amino acid which is already present in the 'P site' of complex and amide bond is formed between amino acids leading to elongation of peptide chain. Then after, the uncharged tRNA which is present in the 'P site' is expelled out the complex via 'E site' while the tRNA that was in 'A site' moves into the 'P site'.

The correct answer is option B. "The tRNA that was in the A site moves into the P site".

Explanation:

In the ribosome complex for translation, the A-site (aminoacyl) acts as the point of entry for the tRNA, and the location at which the first amino acid is bound. Once the first codon has been translated into the first amino acid, The tRNA that was in the A site moves into the P-site (peptidyl). The P-site is the second binding site for the tRNA, and the location at which all the following amino acids are added.

The tRNA is released from the E site of the ribosome and the elongation process finishes while the termination process starts.

Explanation:

When the translocation process is finished the tRNA that is in the E site  of the ribosome is released and the A site of the ribosome reads a stop codon in the mRNA in order to finish the elongation process and start with the termination process.  In the termination process  a termination factor joins the stop codon, the ribosomal subunits split apart, the protein and the tRNA dissociate from one another and the tARN is not in the P site of the ribosome anymore.

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