BIOL 1001 Chapter : BIOL 1001 Chapter 12 Additional
Document Summary
Some genes on chromosomes control cell growth and division. If something affects chromosome structure at or near these loci, cell division may spiral out of control. First abnormal chromosome to be associated with a cancer. Reciprocal translocation of chromosome pieces; #9 had piece of #22 attached to it. By 1882, flemming observed threadlike chromosomes in nuclei of dividing cells. By 1887, weisman suggested that meiosis halves the number of chromosomes when gametes produced. Homologous autosomes (non-sex chromosomes) are identical in length, size, shape, and gene sequence. Homologous chromosomes interact, then segregate from one another during meiosis. Diploid cell has a pair of alleles at each locus. Alleles on homologous chromosomes may be same of different. Mammals, fruit flies: xx is female, xy is male. In other groups xx is male, xy is female. Human x and y chromosomes function as homologues during meiosis. Cultured cells are arrested at metaphase by adding colchicines.
