LIFESCI 7A Lecture Notes - Lecture 15: Tangled, Tubulin, Karyotype
Document Summary
Week 10 notes: cell cycle and cell division. Dna of eukaryotic cells is organized as chromosomes: must ensure both daughter cells receive equal and complete set of chromosomes. Dna must be condensed to t in nucleus, and then condensed more during cell division so it doesn"t get tangled as its segregates into daughter cells. Chromosomes condense and become visible during mitosis with characteristic shapes and sizes. Karyotype: portrait of number and shapes of chromosomes representative of a species. In humans, 22 pairs of homologous chromosomes and 1 pair of sex chromosomes. Each pair of homologous chromosomes has one chromosome from mother and one from father. # of complete sets of chromosomes in cell is its ploidy. In s phase, dna in each chromosome duplicates, but the two copies, sister chromatids, don"t separate. At beginning of mitosis, nucleus has 46 chromosomes--each is a pair of sister chromatids linked at centromere. During mitosis, sister chromatids go to opposite ends of cells.
