Also known as family tree. Twenty different amino acids are used to make proteins. The thousands of different proteins serve many functions in the cell. As enzymes, they control the rate of chemical reactions, and as structural elements they provide the cell with its shape. Proteins are also involved in cell movement and in the formation of cell walls, membranes and protective shells.
Some proteins also help package DNA molecules into chromosomes.
Recombination is a natural process that generates genetic diversity. Specific proteins are involved in recombination. The positions of the cuts can be measured and oriented relative to each other to form a crude map. The precise arrangement of these four subunits is used to transfer and sometimes store genetic information. Somatic cells contain two pairs of each chromosome, while germ cells contain only one.