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  1. What are the two factors responsible for variation in organisms?
    genes and environment
  2. Define Mendelian trait and what is the "pattern of inheritance"?
    • trait due to single gene
    • either/or pattern
    • ex. pea plants, huntington's disease
  3. Define Multifactorial traits
    • traits influenced by the environment
    • ex. heart disease, intelligence, skin color, height, weight..
  4. Define Polygenic traits
    • due to activity of >1 gene
    • bell curve distribustion of phenotypes
  5. True or False..
    It is difficult to predict recurrence for polygenic traits?
  6. Define Empiric Risk and what it's based on
    • predictions of recurrence based on trait's incidence in specific population
    • based on observations/epidemiological studies
  7. Define Heritability
    • % of phenotypic variation due to genes
    • H=1 genes only
    • H=0 environment only
    • Heritability is a component of phenotype attributed to genes
  8. Define Correlation coefficient
    proportion of genes relatives share
  9. Heritability example:
    -Mendelian trait: expect it in 50 sibling pairs
    -Trait is only observed in 37 pairs

    What is the heritability?
    .37/.50= .74
  10. State the degree and percent of shared genes for each:
    1. Siblings
    2. Parent and child
    3. Uncle/aunt and niece/nephew
    4. Grandparent and grandchild
    5. First cousin
    • 1. degree 1, 50%
    • 2. degree 1, 50%
    • 3. degree 2, 25%
    • 4. degree 2, 25%
    • 5. degree 3, 12.5%
  11. Adoption Studies
    • adopted people share environement, but not genes
    • share genes but not environment with biological parents
  12. Twin Studies
    • better info than adoption studies
    • Concordance- percent (%) of pairs in which both twins express the trait
  13. Define SNP
    • stands for: single nucleotide polymorphism
    • a nucletoide site with more than one allele is a polymorphism
    • site is polymorphic is allele is present in >1% of the population
    • on average, between two random individuals, there is one SNP every 1000 bases
    • --> ~3 million differences
  14. Association Studies
    • studies which compare group of interest
    • controls are matched: age, ethnicity, gender, enviornment
    • if SNP is present more often in cases then controls, it is associated with trait and implies SNP may be near gene impacting trait
Card Set
Exam Two chapter 7
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