An mRNA molecule with 1200 nucleotides from the beginning of the start codon to the end of the stop codon will make a polypeptide that is amino acids long. A. 900 B. 400 C. 399 D. 600 E. 1200

C. 399

Explanation:

The process of translation occurs in the ribosome when the nucleotides on the mRNA molecule are read by the tRNA molecule.

The tRNA molecule read the nucleotides in the pair of three nucleotides or triplets and bring a specific amino acid corresponding to the triplet.

Since 3 nucleotides code for an amino acid therefore in the given question if 1200 nucleotides will code for 1200/3 = 400 amino acids.

But it is stated that the nucleotides counted from start to stop codon in which the stop codon does not code for an amino acid.  Therefore from 1200 nucleotides, 3 nucleotides will not code for amino acid so there will be 399 amino acids.

Thus, Option-C is the correct answer.

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