Question

Once a peptide bond has been formed between the amino acid attached to the tRNA in the P site and the amino acid associated with the tRNA in the A site, what occurs next?

A) translocation
B) reading of the next codon of mRNA
C) initiation
D) breaking the codon—anticodon hydrogen bonds holding the tRNA in the A site

Answer 1

The answer is B: reading of the next codon of mRNA

Step-by-step explanation:

First all of, it is important to mention the translation process, in which a protein is created through the reading of some information which is cointained in a molecule called RNA. This process is developed thanks to codons of mRNA that experience a first stage named initiation in which a peptide bond is formed between the amino acid attached to the tRNA in the P site and the amino acid associated with the tRNA in the A site. Then, there is a second stage called elongation, which is related to the creation of a new peptide and so on until complete a repetition of 36000 times. During this process, the new codons of mRNA are read again and again until they complete a long chain. Finally, this translation process ends when the protein built previously is released.

Answer 2

A (Translocation)

Step-by-step explanation:

Translation occurs in a complex containing ribosomal RNA and enzymes, called RIBOSOME.

Translation begins when a transfer RNA (tRNA) attaches to the mRNA in the P site of the ribosome to form an initiation complex. The tRNA's anticodon is complementary to the mRNA's initiation codon. The tRNA carries the amino acid that corresponds to the mRNA codon it reads.

The next mRNA codon becomes exposesd in the middle site (A site) of the ribosome. Another tRNA with the complementary anticodon is attracted to the ribosome and binds to the codon exposed in the A site. The tRNA carries the next amino acid in the polypeptide chain. This initiates peptide formation as the first tRNA transfers its amino acid to the amino acid on the newly arrived tRNA molecule, forming a peptide bond between the two amino acids.

After the formation of the peptide bond, the ribosome uses a ratcheting mechanism to advance (push onward) the mRNA, three nucleotides at a time. The ribosome also simultaneously shifts the tRNA carrying the polypeptide chain (future protein) into its recently vacated site, exposing the codon on the A site again, so that the process can repeat.

This simultaneous movement of tRNA and the mRNA by one codon on the ribosome is referred to as TRANSLOCATION. As this process continues, the polypeptide chain grows longer.

Note that, after the first tRNA gives up its amino acid, it becomes released via the Exit (E) site, so that it can bind to another molecule of amino acid.

Translation ends when a stop codon is read in the ribosome.