Question

The following information should be used for the question.

A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The following charged transfer RNA molecules (with their anticodons shown in the 3' to 5' direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form.

The dipeptide that will form will be
A. proline-threonine.
B. cysteine-alanine.
C. glycine-cysteine.
D. alanine-alanine.
E. threonine-glycine.

Answer 1

After translation, the ribosome produces the dipeptide proline-threonine by matching the 5' CCG-ACG 3' mRNA sequence with corresponding tRNA anticodons and amino acids.

Step-by-step explanation:

The dipeptide that forms after the translation of the 5' CCG-ACG 3' mRNA sequence occurs through the ribosome with the assistance of transfer RNA (tRNA). Given the mRNA sequence, the corresponding tRNA anticodons and amino acids are 5' GGC 3' for proline (Pro) and 5'UGC 3' for threonine (Thr). Thus, the correct dipeptide sequence is proline-threonine, which is option A.

During translation, a tRNA molecule carrying the amino acid proline with the anticodon 5' GGC 3' will base-pair with the first mRNA codon CCG. Next, another tRNA molecule carrying threonine with the anticodon 5' UGC 3' will base-pair with the second mRNA codon ACG. The enzyme peptidyl transferase, a component of the ribosome, catalyzes the formation of a peptide bond between the carboxyl group of the first amino acid proline and the amino group of the second amino acid threonine, resulting in the dipeptide proline-threonine.