Question

In E.coli, a finished polypeptide has $162$ amino acids of which the first amino acid is not methionine compound. How many nucleotides of DNA are required to code this polypeptide?

• A. $486$
• B. $54$
• C. $489$
• D. $492$

Answer 1

Answer: (C)

$489$

There is an intimate connection between genes and synthesis of polypeptides or enzymes The relationship between the sequence, of amino acids in a polypeptide and nucleotide sequence of DNA or mRNA is called genetic code. To code a polypeptide of 162 amino acids 486 nucleotides required but here, methionine is absent. Therefore, 489 nucleotides required and methionine may remove from polypeptide later.
So, the correct option is option C.