Answers to Chapter 4

Answers to Chapter 4 - Answers, Chapter 4 Questions Pierce...

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Answers, Chapter 4 Questions Pierce Genetics Assigned Questions: 10, 14, 15, 19, 20, 22, 24, 31, 32, 33, and 37 14. A Barr body is the inactivated X chromosome in females (XX). Dr. Mary Lyon postulated that one of the two X-chromosomes in human females was inactivated. The presence of Barr bodies is one of the routine screening tests for competitors in the Olympics. All women competitors must have a Barr body. The test is simple and involves scraping cells from inside the cheek and staining the cells, followed by microscopic examination. 19. Jill has hemophilia, meaning she is carrying the recessive gene on both chromosomes. Bill has normal blood-clotting, so his X-chromosome is wild type. All of Jill and Bill’s sons will have hemophilia and all of their daughters will be heterozygotes with normal clotting. However, those daughters could have sons with hemophilia (50 %). For background, look at the story in the text about Queen Victoria and her descendents: some of the daughters and granddaughters were carriers and some of the sons and grandsons had hemophilia. Unlike this question, no one amongst Queen Victoria’s daughters, granddaughters, and great granddaughteers were homozygous for hemophilia. 31. Nondisjunction refers to the lack of separation (or partition) of chromosomes equally to the daughter gametes during meiosis. (a)
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This note was uploaded on 03/30/2008 for the course BIOL 2004 taught by Professor Jofalkinham during the Spring '08 term at Virginia Tech.

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Answers to Chapter 4 - Answers, Chapter 4 Questions Pierce...

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