Final answer:
A codon is a three-nucleotide sequence on mRNA that specifies a single amino acid. This sequence is read from the mRNA in a 5' to 3' direction and is a fundamental component of the genetic code used during protein synthesis. Codons are non-overlapping and directly correspond to amino acids, except for three-stop codons that signal the end of protein synthesis.
Step-by-step explanation:
A unique 3 nucleotide sequence on an mRNA molecule, known as a codon, specifies a particular amino acid during protein synthesis. This sequence is read in a 5' to 3' direction. Each codon is part of the genetic code, a universal code comprising three-base codons that carry the instructions for the amino acid sequence of proteins.
The codons do not overlap and there is no punctuation between codons in mRNA, ensuring a continuous and unambiguous translation process.
There are 64 possible codon combinations, but only 61 of them code for amino acids. The remaining three are stop codons, used to terminate protein synthesis.
A notable codon, AUG, serves a dual role: it codes for the amino acid methionine and also acts as the start codon to initiate translation.
An anticodon sequence on tRNA pairs with the mRNA codon and is responsible for bringing the appropriate amino acid into position during the construction of a protein chain.
This direct correspondence between a codon and an amino acid ensures the proper sequence of amino acids, which dictates the protein's structure and function.