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Multifactorial Traits

Multifactorial Traits. Nomenclature. Mendelian trait- trait caused by alleles on ______________ ____________ trait- trait caused by more than one gene often on different chromosomes Multifactorial (complex) trait- trait that has _______________________ components. Genetics vs Environment.

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Multifactorial Traits

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  1. Multifactorial Traits

  2. Nomenclature Mendelian trait- trait caused by alleles on ______________ ____________ trait- trait caused by more than one gene often on different chromosomes Multifactorial (complex) trait- trait that has _______________________ components

  3. Genetics vs Environment

  4. Polygenic Phenotypes Continuously varying Called a quantitative trait Genes are called quantitative trait ____ _________ is a bell curve

  5. Locus Models Model is based on how many loci code for each polygenic trait As the number of genes increase, so does the amount of phenotypes possible Number of _______________ determines phenotype

  6. Fingerprint Patterns Dermal ridges form patterns of loops, whorls, or arches Mostly determined by ___________ Influenced by touching fingers and toes to amniotic sac during early development Total ridge count (TRC)- count of ridges on all fingerprints; creates bell curve

  7. Height Genetics contribute ________ attainable height Environment determines height actually attained

  8. Eye Color • Probably ______, but not multifactorial • True blue eyes- no active pigment; blue color comes from scattering of light • Lipochromes- greenish-blue pigment • Melanins- brownish pigment • Melanins tend to mask other pigments • Other features (flecks, specks, rings, and streaks) come from distribution of pigment on the iris

  9. Skin Color Color created by bits of melanin secreted by melanocytes within the layers of the skin Variety created by genes coding for amount and distribution of melanin

  10. Cardiovascular System Genetics Amount of cholesterol Blood pressure Clotting factors Environment Diet Exercise

  11. Weight Very complex genetically Feeling of hunger Metabolism Environment Diet Exercise

  12. Empiric Risk Rate at which a certain trait occurs within a _______________ Population may be defined vaguely or very specifically Risk may increase within certain ethnic groups or if family members are affected

  13. Heritability Expresses proportion of phenotype that is contributed to __________ for a particular trait 1.0 would be solely based on genetics Lower number have ________________ components Number can change when environment changes

  14. Coefficient of Relatedness _____________ (P)- individual based relatedness is based upon 1°- Immediate family members (mother, father, sister, brother, children); share _____ of genes 2°- Grandparents, aunts, uncle, nieces, and nephews, grandchildren; share _____ of genes 3°- Great grandparents, great aunts, great uncles, great nieces, great nephews, first cousins, great grandchildren; share ______ of genes

  15. How do we study nature vs nurture? Adoption Studies Adoptee is compared to adopted parents (environment) Adoptee is compared to biological parents (genetics) Twin Studies Prevalence of trait between MZ twins is compared to DZ twins (concordance) Higher differences in concordance show higher differences in heritability

  16. Association Studies Researchers compare SNP’s (single nuclear polymorphisms) between individual with and without disorders Groups with disorder may show a characteristic set of SNP’s Can be used to find genes that are causing disorder Can be difficult because of genetic heterogeneity

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