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17 Cards in this Set
- Front
- Back
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What are the 6 types of Non-Mendelian Genetics?
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A. Incomplete dominance
B. Codominance C. Multiple Alleles D. Pleiotropy E. Epistasis F. Polygenic Inheritance |
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A. Incomplete dominance (define + example)
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Heterozygote show an intermediate phenotype
e.g. Snapdragon colour (see figure 14.10) |
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B. Codominance (define + example)
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Full expression of both alleles in the heterozygote
e.g. ABO Blood Group (figure 14.11) - produces surface glycoproteins (antigens) on red blood cells |
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ABO Blood Group (characteristics)
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3 alleles (A, B, O)
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Phenotype O (genotype/antigen/antibody)
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Genotype: ii
Antigen: none Antibody: Anti-A / Anti-B |
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Phenotype A (G/A/A)
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G: AA / iA
A: A A: Anti-B |
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Phenotype B (G/A/A)
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G: BB / iB
A: B A: Anti-A |
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Phenotype AB (G/A/A)
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G: AB
A: AB A: none |
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In the ABO blood group, alleles I(a) and I(b) are...
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codominant; both are expressed in the heterozygote
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When looking at blood transfusions, only take into account...
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donor antigen
recipient antibody |
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C. Multiple alleles (define + example)
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Some genes may have more than two forms
e.g. ABO blood group has 3 possible alleles |
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Rh system (define)
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Group of antigens found on the surface of red blood cells in addition to ABO antigens
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D. Pleiotropy (define + example)
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Single gene has multiple phenotypic effects
e.g. Sickle-cell anemia 1. Breakdown of red blood cells 2. Clumping of cells 3. Accumulation of cells in the spleen |
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E. Epistasis (define + example)
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Gene at one locus alters the phenotypic expression of a gene at another locus
e.g. Mice coat colour |
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Mice coat colour (epistasis: what happens?)
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I. Gene for coat colour (Black[B]/Brown[b])
II. Second gene, C or c, determines whether or not the colour will be deposited in the hair e.g. Colour deposited: CC or Cc No colour deposited: cc (If mouse if homozygous recessive: cc, coat is white regardless of the genotype at the brown/black locus) |
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F. Polygenic inheritance (define + example)
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Additive effect of two or more genes
- producing a single phenotypic character e.g. skin colour (controlled by at least three different genes) |
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Skin colour (polygenic inheritance: what happens?)
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Controlled by at least three different genes
- A, B, C, are dark genes - a, b, c are light genes e.g. AABBCC genotype -> very dark skinned aabbcc genotype -> very light skinned |
