Biology 1202- Test 1

Biology 1202- Test 1 - Ch 22 Descent with modification A...

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August 23, 2011 Ch. 22 Descent with modification: A Darwinian view of life What is evolution and adaption? Evolution: 2 main ideas o Change over time of the genetic comp. of population o Decent of modern organisms with modification from preexisting organisms Evolutionary adaption o Accumulation of inherited character that enhances organisms ability to survive in specific environments Pre-Darwinian Theory of evolution Lamarck o Inheritance of acquired characteristics through the use or disuse of parts o These modifications are inherited by offspring o Idea turned out to be wrong Examples: giraffes stretching necks and legs Evolution by natural selection Darwin and Wallace developed theory independently o Darwin-voyage of the beagle o Wallace-naturalist in Indonesia Natural selection The unequal survival and reproduction of organisms due to environmental forces resulting in the preservation of favorable adaptions Process “selects” from what is available in the gene pool New characteristics are not created on demand Mechanism behind natural selection Flowchart pg. 458 August 25, 2011 Artificial selection Selective breeding of organisms to encourage the occurrence of desirable traits Analogous to natural selection Figure 22.9 22.3: Evolution is supported by an overwhelming amount of scientific evidence
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Examples of Natural Selection: Figure 22.13 picture Figure 22.13 Results Clicker Question : Within a few weeks of treatment with the drug 3tc, a patients HIV population consists almost entirely of 3tc- resistant viruses? A few 3tc-resistant viruses were present prior to treatment and natural selection…. NATURAL SELECTION AND HIV RESISTANCE: FIGURE 22.14 Single drug theory: o Start with different variants of HIV particles o Single drug reduces fitness of most variants o Resistant variants proliferate Fossil Record Show change in organisms through time Change in types of organisms o Past organisms differ from present-day organisms o Many species have become extinct
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Figure 22.15 Fossil record not only provides ecidence of small-scale changes but of origin of major groups For example, the cetaceans o Figure 22.16 Homologous and Analogous structures Homologous Structures or other attributes in different species that resemble each other because of common ancestry Analogous Structures that are similar in function but not in structure and developmental and evolutionary origin
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Homologous structures: Mammalian Forelimbs: Figure 22.17 Homologous structures: Vertebrate Embryos: figure 22.18 All vertebrates share similar developmental genes Differences arise by some genes being switched on or off at varying times during development Homologous structures: Biochemistry and Molecular Biology DNA is universal genetic material All life forms use approximately the same 20 amino acids to make proteins All use ATP as the primary form of cellular energy All use RNA and ribosomes to make protein
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Biology 1202- Test 1 - Ch 22 Descent with modification A...

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