Final answer:
A codon in the genetic code is comprised of three nucleotides and encodes for a single amino acid or a start/stop signal in the synthesis of proteins.
Step-by-step explanation:
The genetic code consists of the sequence of nitrogen bases in a polynucleotide chain of DNA or RNA. The bases are adenine (A), cytosine (C), guanine (G), and thymine (T) (or uracil, U, in RNA). The four bases make up the "letters" of the genetic code. The letters are combined in groups of three to form code "words," called codons. Each codon stands for (encodes) one amino acid unless it codes for a start or stop signal.
A codon in the universal genetic code is a sequence of three nucleotides that encodes a single amino acid or a start or stop signal during protein synthesis. Each codon corresponds to one of the 20 different amino acids used to build proteins, or signifies the beginning or end of protein synthesis. There are a total of 64 codons, with 61 coding for amino acids and 3 serving as stop signals to mark the end of a protein chain. The sequence of nitrogenous bases (adenine, cytosine, guanine, and uracil in RNA; adenine, cytosine, guanine, and thymine in DNA) in these codons is read from mRNA during the process of translation, where ribosomes synthesize proteins according to the genetic instructions.