Question

Which of the following statements about the genetic code is most correct?

a) Bacteria use a simplified genetic code.

b) Plants and animals have different genetic codes

c) Each amino acid has one unique genetic code

d) Genetic codes are almost the same in all living things

Answer 1

Genetic codes are almost the same in all living things.

The genes of all living organisms are made up of Adenine (A), Guanine (G), Cytosine (C) and Thymine (T). During transcription, the genes gets converted into mRNA which contains Uracil(U) instead of Thymine. This mRNA undergoes translation to synthesise protein. The RNA sequence is read as triplet codes (codon) and each triplet code represents a specific amino acid except for the stop codons (UAG, UGA, UAA). An amino acid can have more than one genetic code. For example phenylalanine is coded by UUU and UUC codons. This is almost universal in all living organisms including micro organisms like bacteria, higher plants and animals. Non universal genetic codes are now being identified in the organelles of certain organisms hence the genetic codes are considered "almost" the same in all living things.