What is a sequence of three nucleotides in mRNA that codes for one amino acid called?

A sequence of three nucleotides in mRNA that codes for one amino acid is called a codon. This term is central to the process of translation in protein synthesis. During this process, ribosomes read the sequence of codons in mRNA to assemble amino acids in the correct order, forming a protein.

Each codon corresponds to a specific amino acid or a stop signal during translation, and the genetic code dictates which amino acid is represented by each codon. This specificity is pivotal for the accurate expression of genes and the functioning of living organisms.

The other terms refer to different concepts related to genetics and molecular biology. An anticodon is a sequence of three nucleotides in tRNA that is complementary to an mRNA codon and plays a role in matching the correct amino acid to the codon during translation. A gene is a segment of DNA that contains the instructions for making a protein or RNA molecule, while an exon refers to portions of a gene that are transcribed into mRNA and are included in the final mRNA molecule after splicing.