BIOL239 Lecture Notes - Lecture 13: Parthenogenesis, Mendelian Inheritance, Mitosis
18 Sep 2018
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When a xx female loses one of her x chromosomes during the first mitotic division after fertilization, a gynandromorphy results, composed of equal parts male and female tissue. Asymmetrical gynandromorphy: large patches of male and female phenotype, but not perfectly bilateral. Most species of eukaryotes are diploid 2n. Polyploids: euploids that carry 3 or more complete sets of chromosomes, e. g. , triploids (cid:894)(cid:1007)x(cid:895), tetraploids (cid:894)(cid:1008)x(cid:895), etc . Monoploids: organisms which have only 1 complete set of chromosomes, usually infertile. Monoploidy and polyploidy are rare in the higher animals. Sterile males (workers) are produced by parthenogenesis. Whereby an unfertilized gamete from the female develops into an embryo. Salamanders, frogs and some reptiles commonly exhibit polyploidy. In plants, larger chromosome numbers often lead to increased size (presumably because there is an increased amount of gene product present) Sterile: e. g. , watermelon, diploid seeds (embryos, triploid seedless (no viable embryos) Union of monoploid and diploid gametes (from a diploid and tetraploid cross)
