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What is a multifactoral trait?
- Trait caused by both genetics and environment.
- ***not sex-linked, not mendelian
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What type of graph is representative of Additive polygenic model?
- Bell-Curve (25%, 50%. 25%), Majority is average
- The 50% will contain one or two dominant (Aa, AaBb, AAbb, aaBB, AaBb)
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What happens to the threshhold when utilizing one type of population?
Remains unchanged
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What is the main difference b/t Threshhold and Additive?
- Threshhold: qualitative, all-or-nothing, liability curve
- Additive: quantitative, average, bell curve
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Why do individuals exceed threshhold of liability?
- 1) many genetic factors
- 2) environmental factors
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If a population or sex has a higher threshhold of liability, will the occurrence rate be high or low?
Low
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What are two factors used to predict recurrence risk?
- 1) Less recurrence risk when degree of relatedness is less
- 2) A more severe condition in a proband of a family equals a higher recurrence
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Rules of recurrence risk calculations
- 1) Increases when more family members are affected
- 2) Increases if proband is the less commonly affected sex
- 3) Increases with more severe phenotype
- 4) Decreases is lesser degrees of relatedness
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What are the true definitions of "nature" and "nurture"?
- Nature: genetics
- Nurture: environment
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Are monozygotic twins different b/c of genetics or environment?
Environment b/c from same fertilized egg = same genes
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Are dizygotic twins different b/c of genetics or environment?
More genetics, 50% just like any other kid
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What is Concordance?
When twins share a trait
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What is discordance?
When twins do not share a trait
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What does Heritability tell us?
The higher the number, the more chance the trait is a reflection of genetics
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What is the Heritability equation?
h=2(Cmz-Cdz)
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