Lecture 23 SRR F-2011

Lecture 23 SRR F-2011 - Biology 313 Lecture 23 Oct 21, 2011...

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Biol 394 in Spain (3 or 6 credits): ISU on the Mediterranean http://www.language.iastate.edu/valencia/ Biology 313 Lecture 23 Oct 21, 2011 ISU Biology & Genetics students crossing a Roman Aquaduct in the Spanish mountains
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Chapter 9: Chromosome Mutations 1. Chromosome morphology 2. Chromosome rearrangements A. Duplications B. Deletions C. Inversions D. Translocations 3. Aneuploidy 4. Polyploidy
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Chapter 9 : Chromosome Mutations (All Ch 9 Problems) Problems Concept Checks 1, 2, 4 - 7 Worked Problems at the end of chapter: 1, 2 Comprehension & Application Questions at end of Chapter: 1-6; 9, 11-13, 16-19, 22, 24, 31-33, 35
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Chapter 9: Chromosome Mutations 1. Chromosome morphology 2. Chromosome rearrangements 3. Aneuploidy 4. Polyploidy A. Autopolyploidy B. Allopolyploidy
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Polyploidy Polyploidy = the presence of more than two sets of chromosomes e.g., a triploid has 3n chromosomes; a tetraploid has 4n ; a pentaploid , 5n ; and so forth. Two major types of polyploidy: 1. Autopolyploidy – all chromosome sets are from a single species 2. Allopolyploidy - chromosome sets are from two or more species
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Autopolyploidy Autopolyploidy – all chromosome sets are from a single species --caused by nondisjunction of a whole set of chromosomes; this happens because cells don’t divide after telophase (of mitosis, meiosis I or meiosis II)
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Autopolyploids can arise through nondisjunction during telophase and cytokinesis (mitosis)
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Autopolyploids can arise through nondisjunction in meiosis I or meiosis II This is an example of how a triploid cell (3n) could arise via nondisjunction caused by a failure of cells to divide after Telophase I; a reductional division does NOT occur (chromosome number is NOT halved)
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Why is an autopolyploid often sterile? -- During gametogenesis, autopolyploids produce gametes with variable numbers of chromosomes (called unbalanced gametes ). -- Fusion of an unbalanced gamete with a normal gamete results in a zygote with an abnormal number of chromosomes. -- This zygote is often not viable because
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This note was uploaded on 11/17/2011 for the course BIOLOGY 313 taught by Professor Steverodermel during the Fall '11 term at Iowa State.

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Lecture 23 SRR F-2011 - Biology 313 Lecture 23 Oct 21, 2011...

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