GENE 3200 Lecture Notes - Lecture 1: Sister Chromatids, Monosomy, Aneuploidy
Document Summary
There is no association of chromosome # with genome size or organism complexity. Normal meiosis: results of meiosis i- homologous chromosomes split (red and blue, results of meiosis ii- sister chromatids split. In autosomes, most trisomies and all monosomies fail to develop: trisomies of chromo 13, 18, and 21 are seen in newborns. Polyploidy: complete extra sets of chromosomes, autoplolyploidy- additional sets of chromo from same species, allopolyploidy- additional sets of chromo from another species, produces a hybrid of 2 different species, produces viable offspring but they are usually infertile. Induce cytokinesis failure and make a diploid organisms. In tetraploid, every chromosomes has a pair because even #, but in triploid, the chromosomes are not even, so there is massive nondisjunction (aneuploidy). In meiosis i (mitosis), homolog chromosomes ignore each other. However, in meiosis ii, the gametes result in problems due to nondisjunction. Polyploidy in agriculture: create sterile fruit such as seedless watermelon (seed is the fertile part).
