Lecture 3 Slides

Lecture 3 Slides - Evolutionary Change through Spontaneous...

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Artificial selection: People select which mutants to propagate Allows more rapid evolutionary change than usually occurs in nature Evolutionary Change through Spontaneous Mutation and Natural or Artificial Selection Changes in DNA base sequence occur through errors in duplication of chromosomes. These are heritable if they occur in germ cells (gametes). Mutations that lead to changes in structure of the proteins encoded by the gene may confer advantage or disadvantage upon the organism Natural selection : reproductive success is determined by environmental conditions not imposed or shaped by man
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Zea mays mexicana (teosinte) Modern corn F1 hybrid Unfertilized kernels Artificial selection has greatly Artificial selection has greatly changed corn over 6,000 years changed corn over 6,000 years Changes to 1,200 Of 59,000 total Genes Lengthened single ear Many more kernels Disappearance of hard case that allows survival in bird digestive tract
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Male organs in tassels of corn 20,000 pollen grains per kernel Pollen nucleus divides - one tunnels to egg and forms endosperm The other fertilizes
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Ovule is in ear of corn, growing from side of stalk Pollen tube grows downward to fertilize style on silk strand that exits the ear
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Selling corn to farmers • Selection for strains with upright stalks that tolerate crowding and are easily harvested • Hybrid (F1) strains show heterosis: produce good yield • Next (F2) generation is not productive • Forces farmers to buy new (sometimes patented) seed each year • Genetically engineered corn - e.g., Monsanto YieldGard - resists root worm and corn borer pests, but requires use of Roundup insecticide and costs more
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Photosynthesis : Plants use solar energy to fix Carbon and generate Oxygen in the process Sugars used to generate ATP through glycolysis and oxidative phosphorylation Hydrocarbons can be used for structural components of cells; other atoms (N, P, etc.) are often added
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Plants have two ways of fixing Carbon 95% of plants use the “C-3” method CO 2 molecules are added to 5-C ribulose biphosphate,
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This note was uploaded on 05/18/2008 for the course BIO 105 taught by Professor Adler,irschick,podos during the Fall '08 term at UMass (Amherst).

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Lecture 3 Slides - Evolutionary Change through Spontaneous...

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