Lec 15 - Homework: two allele crosses Genotype: AaBb. What...

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Homework: two allele crosses Genotype: AaBb. What kinds of gametes are produced? (A) AA aa BB bb (B) A B a b (C) AB Ab aB ab
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Explain the results of a cross with 2 loci AaBb x aabb Ab AB aB ab ab AaBb aabb aaBb Aabb 25% 25% 25% 25% offspring frequency ratio 1: 1: 1: 1
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BIS2B Fall 2009 (Keen) Lecture 15 . More on Genetics 21 October How are the laws of probability applied to offspring formation? How does the genotype influence the phenotype? Students should be able to: explain Mendel’s two laws predict the frequencies of particular offspring genotypes and phenotypes given parental genotypes diagram a test cross and explain possible outcomes explain the roles of multiple alleles, pleiotropy, and epistasis in determining the phenotype differentiate linked and unlinked genes and explain how crossing over affects linked genes explain the genetic basis of polygenic traits
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THE CHROMOSOMAL THEORY OF INHERITANCE THE CHROMOSOMAL THEORY OF INHERITANCE
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A few terms: Allele = a version of a gene Genotype = the genetic composition of an organism; in diploids, it will consists of two alleles. Homozygote (e.g. AA or aa) Heterozygote (e.g. Aa) The protein products made by alleles determine the phenotype, at least in part
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How alleles influence the phenotype: How alleles influence the phenotype: Two alleles Two alleles • For traits determined by a single locus, two alleles result in as many as three potential phenotypes. For example, to distinguish blue and green budgies, you need to realize that blue is a structural color of the feathers. There are two pigment alleles: Y and y. Y makes yellow pigment; y is defective and makes a colorless pigment. Blue + yellow = ?
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YY yy What color do you think heterozygotes (Yy) are? Explain your reasoning based on how the alleles function (based on pigment protein production).
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If we have a green bird, how can we determine its genotype?
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Punnett Square Test cross: mate an organism of unknown genotype to a homozygous recessive individual y y Y Y Yy Yy Yy Yy Yy yy y y Y y Yy yy Calculate the expected ratios of blue and green phenotypes
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Lec 15 - Homework: two allele crosses Genotype: AaBb. What...

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