From genes to proteins
Proteins are the workhorses of biochemistry. Practically
all chemical reactions in a cell are catalyzed by proteins
and many proteins have diverse other functions. From the
chemical point of view, proteins are long chains of
chemicals called amino acids. There are 20 amino acids
that are the building blocks for most proteins in most
organisms. Amino acids are coded by triplets of
nucleotides, which are also called codons. A stretch of a
genome that codes for a given protein is called a gene.