BSC 1005 Lecture Notes - Lecture 20: Asexual Reproduction, Germ Cell, Sexual Reproduction
Document Summary
Germ cells, homologues, alleles, chaisma, chromatids, synapsis, crossing over, sex cells, Do not have a direct role in reproduction. These are the gametes or sex cells that play a direct role in reproduction. The two chromosomes that make up a matched pair in a diploid cell of an organism. One chromosome of this pair is inherited from the father. Homologous chromosomes are of the same length, centromere position, and possess the same genes or alternative form of a gene. Sexual life cycle involves the alternation of haploid and diploid stages. Dna is not replicated between meiosis i and meiosis ii. Chromosome number is reduced to half at the end of meiosis i. Prophase i : nuclear membrane and nucleolus disappear; chromosomes condense. Each duplicated chromosome lines up with its partner and makes a homologous pair. Chiasmata and crossing over may occur between the non-sister chromatids of a homologue.
