Zoology - Lecture 10 - Lecture 11 Sexual Reproduction and...

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1 Lecture 11 Sexual Reproduction and Genetic Variability Mutations • Any physical change of nucleotide bases • May occur at any site along a strand of DNA • May be either detrimental to the cell, helpful, or essentially have no detectable impact on cell function • Account for the wide variety we see among organisms Genetic Variation • Allele: alternate form of a gene – Examples: • Sickle cell disease: DNA reads - ...CTC… vs. …CAC… • Nematode aging - One version lives 2 times longer Natural Selection: REVIEW!!! “enhanced survival and reproductive success of certain individuals from a population based on inherited characteristics.” Sexual Reproduction: Combining Genes • Conjugation • “bacterial sex” • ~3.5 bya (fossil evidence) • Genes pass from one cell to another via a sex pilus • May occur among unrelated organisms NOT REPRODUCTION: IT ALTERS THE GENETIC MAKEUP OF EXISTING ORGANISMS BUT DOES NOT PRODUCE NEW INDIVIDUALS Sexual Reproduction: Fusion of two haploid cells • Cells must meet and fuse completely
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2 Meiosis -- the process of nuclear division that occurs in sex cells -- results in the reduction of chromosomal number (i.e. 2n parent cell produces n daughter cells) Sexual Reproduction and Genetic Variability Meiosis Where do I come from? Where do
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Zoology - Lecture 10 - Lecture 11 Sexual Reproduction and...

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