biol1201 mar 25

biol1201 mar 25 - 3/25/08 Calico and tortoiseshell cats are...

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3/25/08 Calico and tortoiseshell cats are examples of X chromosome inactivation. X chromosome inactivation occurs at random and all but one x chromosome is active. What is the chance that two parents with sickle trait (carriers) will have a child with sickle cell? 25% Why is the sickle allele maintained in populations, particularly in Africa and the Mediterranean Sea area? Heterozygotes are immune to malaria. Testing for rare diseases saves money – true What does it cose to screen a newborn? $30 For an autosomal recessive trait, if two affected individuals have children all of their children will have the trait. True How many Barr bodies are there in the nucleas of a Tumer’s female (XO 45) cell? 0 How many Barr bodies in the preceding Klinefelter male (XXXXY 49) cells? 3 A Klinefelter male, XXY 47, is an example of Aneuploidy 1. Dominant/Recessive Traits a. Eye-color i. Polygenic inheritance 1. At least 2 genes control eye color. b. Sickle Cell Anemia i. Homozygous recessive (autosomal) ii. Differs in one amino acid in the 6 th position in the beta chain iii. A valine (hydrophobic) is found in the sickle cell hemoglobin iv. A glutamate (negatively charged) is found in the normal hemoglobin 1. Hemoglobin a. Protein consisting of 4 polypeptide chains b. 2 alpha chains, each 141 amino acids long c. 2 beta chains, each 146 amino acids long v. The situation of sickle-cell anemia is Pleiotopic
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biol1201 mar 25 - 3/25/08 Calico and tortoiseshell cats are...

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