3. Ch14_Nov_27_30_ - Ingeneral,:onshasa 1 2 3 4 5 Inversion...

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11/27/09 1 In general, which of the following chromosomal muta:ons has a greater chance of lethality than the others? 1. Inversion 2. Duplica:on 3. Dele:on 4. Transloca:on 5. All have an equal chance of causing lethality. Aneuploidy- loss or gain of one or more chromosomes e.g. Down Syndrome Polyploidy- multiple copies of chromosomes Monosomy – lack 1 chromosome from 2n number ( i.e., 2n-1) Changes in Chromosome Number
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11/27/09 2 Using Drosophila as an example… Changes in Chromosome Number Occur very rarely in many spp, but frequently in humans As high as 10-30%! Most aneuploids are lethal (in humans, cause early miscarriage) due to effects on GENE DOSAGE In rare cases, an aneuploid state is viable E.g., chromosome 21, sex chromosomes Efects oF Aneuploidy Viable aneuploids in humans
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11/27/09 3 Caused by NONDISJUNCTION during meiosis Aneuploidy MI Nondisjunction MII Nondisjunction Aneuploids generate aneuploid gametes… Meiosis in MONOSOMIC individual Meiosis in TRISOMIC individual
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This note was uploaded on 01/10/2010 for the course BIOLOGY biol2040 taught by Professor Tamarakelly during the Fall '09 term at York University.

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3. Ch14_Nov_27_30_ - Ingeneral,:onshasa 1 2 3 4 5 Inversion...

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