Use the following information to answer 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.

Which of the following dipeptides will form from this mRNA?
A) cysteine-alanine
B) proline-threonine
C) glycine-cysteine
D) alanine-alanine

Question

Use the following information to answer 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.

Which of the following dipeptides will form from this mRNA?
A) cysteine-alanine 
B) proline-threonine 
C) glycine-cysteine 
D) alanine-alanine

Quizplus · Accepted Answer

The mRNA sequence 5′-CCG-ACG-3′ codes for the amino acid sequence proline-threonine. The tRNA with the anticodon 3′-CGG-5′ will pair with the codon 5′-CCG-3′, bringing in the amino acid proline. Similarly, the tRNA with the anticodon 3′-CGU-5′ will pair with the codon 5′-ACG-3′, bringing in the amino acid threonine. Therefore, a dipeptide of proline-threonine will form.

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