Gene Expression: Transcription and Translation

DNA stores information, but that information must be decoded to build the proteins that carry out life's functions. The flow of information from gene to protein is often summarized as the central dogma: DNA is transcribed into RNA, and RNA is translated into protein.

Genes and the Genetic Code

A gene is a length of DNA that codes for a specific polypeptide. The instructions are written in the sequence of bases, read in groups of three called codons. Each codon specifies one amino acid. Because there are four bases and codons are three bases long, there are 4^3 = 64 possible codons. These encode the 20 amino acids plus start and stop signals.

The genetic code has several important properties. It is degenerate, meaning most amino acids are specified by more than one codon. It is universal, b