BIO 110 G Course Notes - Biology 110 G 9:57:00 AM I Darwin's Observations A All species have great potential fertility could have exponential population

BIO 110 G Course Notes - Biology 110 G 9:57:00 AM I...

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Biology 110 G – 1/30/08 25/01/2008 09:57:00 I. Darwin’s Observations A. All species have great potential fertility; could have exponential population  growth. B. Populations tend to be stable C. Environmental resources limited D. Organisms within a populations are varied 1. No such thing as an ideal species E. Much variations are inherited II. Darwin’s Inferences A. More individuals than environment can support causes a struggle for  existence B. Within a population, the inherited traits of some individuals make them more  able to survive and reproduce in the face of certain environmental conditions;  Natural selection C.  Over time, those traits that convey an advantage will change the  characteristics of a  population, leading to a new species. III. Main Points in  The Origin of Speciesˆ A. Evolution Occurs – the diversity of life has arisen by descent with modification B. Natural Selection is the main mechanism by which evolution operates over  many generations IV. Natural Selection A. Is differential success in reproduction B. Occurs through an interaction between the environment and the variability  inherent among the individual organism in a population 1. Whatever is conveying this trait must already be there, but it can be  continually conveyed 2. Mutations that change the attributes are carried on C. Produces adaptations in organisms that “fit” the environment
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V. Three Conditions for evolution by natural selection to proceed A. Variation 1. Variation for a particular trait exists within a population  2. ex. beak size in different finches; must be inheritable B. Heritability of that variation C. Differential reproductive success (variation influences who survives and  reproduces)  1. Variation must influence who survives and who reproduces VI. Drug Resistance A. Viruses go through evolution  1. Some HIV drugs go through evolution to resist some of the drugs  including 3TC VII. Evidence of Change Over Time A. The Grand Canyon 1. Strata of sedimentary rock at the Grand Canyon VIII. Evidence of Common Descent Homology – Similarity that exists in species descended from common acestor
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Session 6 2/4/08 I. Mitosis - Part A. Cytokinesis – last step; the division of the cytoplasm B. Results – G1, early interphase of daughter cells  1. Cells resume the normal functions or enter another division cycle C. Summary of Mitosis 1. One division of nucleus 2. Two daughter cells produced per cycle 3. Preserves chromosome number 4. Daughter cells genetically identical 5. Occurs in somatic cells 6. Occurs throughout life cycle  D. Human Karyotypes – 46 chromosomes, but 23 pairs E. Link Division between cell division and evolution 1. Mitosis   Cell division and reproduction of cells with the same genetic F. Mitosis – “The Dance of My Two Sister Chromatids”   Two sister chromatids  that are being created then being put into different cells.   II. Meiosis – Making gametes A. One Function – Make gametes   create sex cells B.   Human is a diploid organism – 46 chromosomes  1.
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