Biol 101 12 February 2008

Biol 101 12 February 2008 - 2 alike alleles – homozygous...

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Biol 101 12 February 2008 Meiosis o Special cells in gonads undergo meiosis and become gametes o Gametes meet at fertilization o Makes haploid cells; can occur without fertilization o Come together to make a diploid cell – “zygote” (immediate result of fertilization) o Meiosis occurs less than mitosis – there is less chance for a mistake o Nondisjunction – cells don’t separate all the way; how you get a person with extra chromosomes (during meiosis with gametes); somatic mutation – where the chromosomes separate the wrong way inside the body (Y, XXY) o Meiosis I – homologs separate o Mitosis o Meiosis II – sister chromatids separate Results of mitosis and meiosis o Mitosis Two diploid cells produced Each identical to parent o Meiosis Four haploid cells produced Differ from parent and one another Gregor Mendel o Genes and alleles (genes at the same locus for the same trait)
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Unformatted text preview: 2 alike alleles – homozygous 2 unlike alleles – heterozygous Appearance – phenotype (how it turns out; could be determined by the environment) – genotype + environmental factors Genes – genotype o Recessive – expressed only when it is by itself (both alleles have the gene, only one allele) o Dominant – always expressed Co-dominant alleles – both expressed (AB blood type) (enzyme glycolipid on RBCs A B O) o Dogs F – Floppy f – not floppy Mom – Ff, Dad – ff Gametes from mom: F, f ; Dad – f Offspring: Ff, ff (equal portions) – floppy: non floppy :: 1: 1 F f F FF Ff f Ff ff o Sex-linked (linked to the sex chromosome) Mom: XtXt; Dad: XTY Mom’s Gametes: Xt; Dad’s Gametes: XT, Y Offspring: ½: XTXt, ½: XtY...
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This note was uploaded on 03/29/2008 for the course BIOL 101 taught by Professor Hogan during the Spring '08 term at UNC.

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Biol 101 12 February 2008 - 2 alike alleles – homozygous...

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