The two principal gonadotropins in vertebrates are luteinizing hormone (LH) and follicle-stimulating hormone (FSH), although primates produce a third gonadotropin called chorionic gonadotropin (CG). LH and FSH are heterodimers consisting of two peptide chains, an alpha chain and a beta chain.H and FSH are secreted by the anterior pituitary gland, while hCG and eCG are secreted by the placenta in pregnant humans and mares, respectively. The gonadotropins act on the gonads, controlling gamete and sex hormone production.
Anything that can bring about a mutation in DNA is called a mutagen. Most mutagens fall into one of two categories: They are either a form of energy or a chemical. In addition to X rays, other forms of radiation that can cause mutagens include ultraviolet radiation, gamma rays, and ionizing radiation.
Mutations can also be caused by exposure to specific chemicals or radiation. These agents cause the DNA to break down. This is not necessarily unnatural  even in the most isolated and pristine environments, DNA breaks down. Nevertheless, when the cell repairs the DNA, it might not do a perfect job of the repair.he causes of mutations. 1. DNA fails to copy accurately. Most of the mutations that we think matter to evolution are naturally-occurring.. For example, when a cell divides, it makes a copy of its DNA  and sometimes the copy is not quite perfect.