Question

Consider the following sequence on mRNA, AUGGCAGUGCCA. Assuming that genetic code is overlap then how many number of codon may be present on this genetic code?

• A. 9
• B. 10
• C. 8
• D. 11

Answer 1

The correct option is B 10

A codon is a three-letter nucleotide sequence that encodes a particular amino acid. The codon is, thus, a triplet.

Each codon codes for a single amino acid only. Hence, the codon is unambiguous and specific. For example, UUU codes for phenylalanine, AAA codes for lysine, etc. Some amino acids are coded by more than one codon e.g., threonine, leucine, proline etc.

If the genetic code is overlapping in the given question, which is not found in living organisms, in general then for the following sequence of mRNA AUGGCAGUGCCA ten codons may be present. These are AUG, UGG, GGC, GCA, CAG, AGU, GUG, UGC, GCC, CCA.

So the correct answer is B. Had the code been non-overlapping there would be only 4 codons in the given sequence of mRNA. An example is given in the image shown to make things clear.