Triplet code

Triplet Code is a fundamental concept in the field of genetics and molecular biology. It refers to the way in which the genetic code is read on the DNA and RNA molecules, with each set of three nucleotides corresponding to a specific amino acid or signal.

Overview

The triplet code is the basis for protein synthesis in all living organisms. Each triplet, also known as a codon, is made up of three nucleotides. There are four types of nucleotides in DNA: adenine (A), cytosine (C), guanine (G), and thymine (T). In RNA, thymine is replaced by uracil (U). This gives a total of 64 possible combinations of nucleotides in a triplet code (4^3).

Codons

Each codon corresponds to a specific amino acid or a stop signal. For example, the codon AUG codes for the amino acid methionine and also serves as the start signal for protein synthesis. There are also three stop codons (UAA, UAG, UGA in RNA; TAA, TAG, TGA in DNA) that do not code for any amino acid and instead signal the end of protein synthesis.

Degeneracy of the Genetic Code

The genetic code is said to be degenerate because there are more codons (64) than there are amino acids (20) to code for. This means that most amino acids are coded for by more than one codon. For example, the amino acid leucine is coded for by six different codons (UUA, UUG, CUU, CUC, CUA, CUG).

Reading Frame

The concept of the reading frame is crucial to understanding the triplet code. The reading frame refers to the way in which the nucleotides are grouped into codons. If the reading frame is shifted by one or two nucleotides, a completely different set of codons, and therefore a completely different protein, can be produced. This is known as a frameshift mutation.

See Also

• Genetic Code
• Codon
• Nucleotide
• Protein Synthesis
• Frameshift Mutation