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 and egg cells are haploid cells, meaning they have half the number of chromosomes as all other cells in the body. Humans have 46 chromosomes, so human reproductive cells will have 23. Sperm and egg cells are haploid cells, meaning they have half the number of chromosomes as all other cells in the body.