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.
A regular human sex cell (unless something goes wrong) is haploid (meaning that it has half the chromosomes of a normal body cell). Since normal human body cells have a total of 46 chromosomes (23 pairs), a human sex cell (like sperm) has 23 chromosomes.As there are 23 chromosomes, the sex cells do not have pairs of chromosomes. The fact that sex cells only have half the number of chromosomes as regular cells (no pairs) is a very good thing. regular human sex cell (unless something goes wrong) is haploid (meaning that it has half the chromosomes of a normal body cell). Since normal human body cells have a total of 46 chromosomes (23 pairs), a human sex cell (like sperm) has 23 chromosomes.