Biology 1201A Lecture Notes - Lecture 4: Kinetochore, Microtubule, Ploidy
Document Summary
Produces genetically unique cells due to genetic recombination. Halves the ploidy halves coefficient on. 2 pairs of tetrads line up in metaphase 1. * during anaphase 1 homologous chromosomes are divided, then in anaphase 2 sister chromatids are divided. More potential for error because there are more steps. Produces identical cells genetic recombination doesn"t occur. Genetic recombination: physical exchange of sequences between chromatids of homologous chromosomes. Homologous chromosomes stack" on top of one another and a synaptonemal complex forms between homologous chromosomes. Segments of chromatids from chiasmata (chiasmata = the cross over region) 4 dna backbones are broken and free ends are exchanged. Backbones are reglued together after pieces are exchanged. This process makes new combinations of alleles across different genes doesn"t make new alleles. One recombination event: is one physical exchange of gene segments. Multiple recombination events can occur on a pair of homologous chromosomes.