Genetics Feb 5 chapter 6

Genetics Feb 5 chapter 6 - Chapter 6 Gene Interaction A...

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Chapter 6 Gene Interaction A goal of genetic analysis is to identify all the genes that affect a specific phenotype and to understand their genetic, cellular, developmental and molecular roles. Interactions between the alleles at one locus Types of Dominance o Students should know two examples for each of the following types: o (One example from the disease sickle cell anemia and ot??????? Complete Dominance o One allele is completely dominant to another when the heterozygote has the same phenotype as one of the two homozygotes. BB=black, Bb= black, bb= brown This is complete dominance at the level of coat color The dominant allele is said to be the one found in the homozygote that has the same phenotype as the heterozygote. Incomplete dominance o One allele is said to be incompletely dominant to another allele when the heterozygote has a phenotype that is intermediate between the two homozygotes. Codominance One allele is said to exhibit codominance with respect to another allele when each allele produces its full phenotype in the heterozygote. Polymorphism in the loosest sense means that there exists in a population more than one discretely different forms of a character. **In the most qualified sense polymorphism refers to the existence of more than one allele at a locus in a population. If there are only two such alleles, ?? There must be at least two alleles where their proportion is greater than .01 Multiple allelism refers to the existence of more than two alleles at locus. A locus that exhibits multiple allelism maybe polymorphic. insert at 21:20 The ABO blood type system in humans provides examples of polymorphism, multiple allelism, complete dominance and codominance. An antigen is anything an antibody will bind to. Usually its proteins on the surface on the cell.
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CH 2 problem 63 Chapter 3 pg 89- 106 stop before recombination 112 organelle genes section 3.5 up to pg 114 stop at Cytoplasmic segregation don’t do 116 at the bottom Cytoplasmic mutation in humans and finish the chapter Solved problems 1 and 2 14, 16 17 18 19 20 21 22 23 25 27 36 37 38 40 When you work the problems in chapter 3m, start at the problem set and write out AaBb X AaBb A_B_ | A_bb | aaB_ | aabb 9 3 3 1 A typical genetics problem concerning the ABO blood groups Another example of multiple allelism or polymorphism. Clover is in the genus Trifolium . Presence/ absence The chevron pattern on the leaves of clover in the genus Trifolium is determined by several alleles. The important question is why are there so many alleles at this locus We will discus the dominance interactions of the HbB allele and the HbS allele found at the locus coding for the * B* chain of the hemoglobin molecule. Sickle-Cell anemia
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This note was uploaded on 11/11/2009 for the course BIO Genetics taught by Professor Saxena during the Spring '08 term at University of Texas.

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Genetics Feb 5 chapter 6 - Chapter 6 Gene Interaction A...

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