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BIOL 160
Nov 14, 2023
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Chapter 13 Genetic Variation Independent assortment : during meiosis chromosomes lineuprandomly during metaphase a # *** o S X XX neenie xXXX XX for) -> causes 223 possible combinations of homologs in humans -> 8 4 million possible gametes that are genetically different -Crossing Over : during meiosis 1 chromosomes exchange segments of genes , which produces new combinations of alleles within a chromosome these combinations do not exist in either parent crossing over produces limitless combinations homologous chromosome pairs : fertilization : 23 chromosomes from mom , any sperm and any egg from different individuals 23 matching chromosomes from dnd Al come together randomly (no regard to the alleles contain versions of the same genes that they carry a eggs of sperm , 2 parents aploid cells : can create 70 6x101 unique offspring sperm + egg cells : have half of the amount of chromosomes I chromosome per gene/allele (n = 23) # ploid cells : have 2 versions of each type of chromosome (2n=46) Meiosis : specialized diploid cell splits in half twice , creating 4 genetically distinct cells Meiosis Prophase I apparatus begins to form Ses DNA conden DNA crossover occurs XX (4 total chromations) sex chromosomes don't crossover if Xy bes a b nuclear envelope breaks down Metaphase 1 : each chromosome lines up next to its homologous pair each chromosome is attached to the · ** A Spindle apparatus - S # independent assortment occurs Anaphase I : ** chromosomes separate is more to opposite poles X telophase I : nuclear membrane reforms chromosomes decondense - cleavage furrow or is results in 2 haploid cells ul 23 chromosomes each #eiosis II : Prophase II : no DNA replication involved DNA condenses · spindle apparatus reforms sister chromatids attach to kinetochores X - * & S Metaphase II : & & sister chromatids line up at the metaphase plate · & > Anaphase 11 : - [ [ Sister Chromatids are separated , making daughter C 3 7 Telophase 11 : chromo somes · clearage furrow or is -chromosomes decode a b feature mitosis # of cell Meiosis 1 2 division # of chromosomes (compared to same 12 Parent cell) identical daughter yes no cells ? to purpose asecuadnction Sexual reproduction is
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