Question

Which of the following is not a salient feature of genetic code?

• A. Nearly universal
• B. Ambiguous
• C. Triplet
• D. Degenerate

Answer 1

The correct option is B Ambiguous

The sequence of nucleotides in DNA that determines the sequence of amino acids in a polypeptide via an mRNA intermediate is known as genetic code.

The genetic code is a triplet code. Three consecutive nucleotides in mRNA constitute a codon which codes for a particular amino acid.

The salient features of genetic code are:
- Nearly universal: genetic code is nearly universal.
For example - UUU is a genetic codon that codes for phenylalanine right from bacteria to humans. Mitochondrial codons and codons in some protozoans are an exception to this rule.

- Triplet: genetic code is triplet in nature. Three consecutive nucleotides in mRNA constitute a codon which codes for an amino acid.

- Unambiguous: the genetic code is unambiguous because one codon codes for only one amino acid. Example - the codon CCU always codes for the amino acid proline.

- Degenerate: more than one codon codes for an amino acid.
Example - Both AGU and AGC code for the amino acid serine.