BIO 201 Lecture Notes - Lecture 30: Monosomy, Nondisjunction, Aneuploidy
24 Apr 2017
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Duplication of one genome followed by cell division or budding 2nd generation cells are genetically identical* to parents and each other. Very little change from generation to generation. Combine genetic material from two parents next generation is genetically distinct from parents and from each other. Problem: how to maintain appropriate chromosome numbers from one generation to the next. Solution: halves genomes before combining meiosis. Form haploid germ cells (egg and sperm) via meiosis (n = 23) Coming together of egg (n) and sperm (n) (fertilization) formation of diploid zygote (2n) mitosis (2n) multicellular diploid organism (2n) Meiosis i: a. metaphase i: chromosome align on metaphase i plate. Homologs adjacent to each other (synapsis: homologs exchange dna (chiasma, anaphase i: homologous chromosomes segregate (sister chromatids remain together!, cytokinesis i. Meiosis ii: metaphase ii: chromosomes align on metaphase plate, anaphase ii: sister chromatids separate, cytokinesis ii. Meiosis 223 possible genetically distinct haploid gametes (8,388,608) Fertilization (223)(223) or 70,368,744,177,644 possible genetically distinct offspring!
