BIOL 120 Lecture Notes - Lecture 9: Mendelian Inheritance, Nondisjunction, Meiosis
Document Summary
At individual level bad, but in long run often good or can lead to good things (more complex organisms that could adapt better0. When cells multiply by asexual means, the number of chromosomes is kept at 2n. What happens during sexual reproduction where two cells fuse? o. The life cycles of diploids organisms require a phase where cells are haploid. A mechanism is required to reduce the number of chromosomes by half so that following fertilization the number of chromosomes returns to the original level. The process of producing haploid cells (1n) for sexual reproduction. This keeps number of chromosomes constant from generation to generation. Meiosis consists of one replication of the cellular dna but 2 cell divisions. This leads to the productin of 4 haploid cells rather than 2 diploid cells. In synapsis (crossing over), the homologous dna segments can interact and in some cases pieces of dna can be swapped from one chromatid to another.
