Question

There are 81 amino acid residues in the precursor molecule of bovine insulin. What is the least number of bases that must be in the DNA chain that codes for this molecule?

Answer 1

If you count the methionine expressed for the start codon as part of the precursor protein, then (81+1)*3. (The start codon is expressed, but the stop codon isn't.) 

Answer 2

Answer:

246 amino bases

Explanation:

An amino acid is coded by three bases. However, in a DNA molecule, there is coding that takes place. In DNA replication, the start and stop codons are not expressed during the formation of the double helix. Hence, an extra amino acid will be needed. In fact, this can be expressed mathematically like this:

$Number of bases = (n+1) * 3$

where n is the number of amino acid residues. Therefore, taking 81 amino acid residues yields:

                 N = $(81+ 1) * 3\\246$

Therefore, the least number of bases needed will be 246