Final answer:
The genetic code translates three-letter DNA codons into amino acids for protein synthesis. There are 64 codons creating a universal code for 20 amino acids, with most amino acids encoded by multiple codons.
Step-by-step explanation:
The genetic code is a system that translates DNA codons into the essential amino acids that form proteins. DNA and RNA contain four nucleotide bases, but proteins are made up of 20 different amino acids. This translation is possible because each amino acid is encoded by a sequence of three nucleotide bases—a triplet or codon—in the DNA. The ribosome reads these codons in the mRNA, beginning from the 5' end, and correlates them with specific amino acids in a process called protein synthesis.
There are a total of 64 possible codons, all of which are part of a standardized coding table used universally by almost all living organisms. Some amino acids, like methionine and tryptophan, are specified by a single codon, while others may be encoded by multiple codons, reflecting the 'degeneracy' of the code. For example, the amino acid glycine is encoded by four codons (GGA, GGC, GGG, and GGU), which shows that although codons for the same amino acid may differ, they typically share a common base sequence.
Certain codons also serve specific roles in protein synthesis; for instance, the AUG codon is an initiation codon signaling the start of a protein, while the codons UAA, UAG, and UGA are termination codons signaling the end of a protein chain. This orderly and universal coding system explains how cells translate genetic instructions into functional proteins.