Group of three bases on DNA which code for an amino acid?

• A. Haploid cell
• B. Alleles
• C. Codon/Triplet
• D. mRNA

Answer: (C)

A set of three nucleotides that specifies an amino acid is the unit used to translate the genetic code. In DNA this is called a triplet, and in the RNA language it’s a codon. Each codon/triplet maps to one amino acid during protein synthesis, and there are 64 possible codons to code for the 20 amino acids (with some codons signaling the start or a stop to translation). This is why the correct term here is codon/Triplet.

The other terms refer to different ideas: a haploid cell relates to chromosome number, alleles are different versions of a gene, and mRNA is the molecule that carries the coded message from DNA to the ribosome but is not the three-base DNA unit itself.