An mrna is 429 nucleotides long. the number of amino acids in the polypeptide chain formed from this mrna is
(a) 143.
(b) 142.
(c) 141.
(d) 429.
(e) 428.

B. 142. This is because one of the molecules has to be a stop codon which doesn't code for an amino acid. So there are only 426 nucleotides coding for the polypeptide chain. It takes 3 nucleotides to code for an amino acid. So 426 divided by 3 is 142, which is the amount of amino acids that will be part of this chain.

Called for cell.