Substances that cause DNA mutations are known as mutagens, and mutagens that cause cancers are known as carcinogens. Particular substances have been linked to specific types of cancer. Tobacco smoking is associated with many forms of cancer, and causes 90% of lung cancer.
Human diploid cells have 46 chromosomes and human haploid gametes (egg and sperm) have 23 chromosomes. Retroviruses that contain two copies of their RNA genome in each viral particle are also said to be diploid.
Sperm are haploid; they contain one set of 23 chromosomes. They are created by the cellular division process known as meiosis, which creates 4 sperm from a single germ cell. Theyâre also very small, only about 50Î¼m long. Sperm are ejaculated in semen, a basic fluid with a pH of about 7.4.