1. Chapter 9: Genetics 9.13-9.15 Non-Mendelian Genetics – Pt.3 Polygenic, Pleiotropy, Environment Pgs. 168-170 Objective: I can apply and combine all genetics principles learned so far in order to solve increasingly complex problems that explain human genetics that do not fit Mendel’s laws.

2. Polygenic Inheritance Several Genes (each with own alleles) determine ONE character – –Two genes for Height (Gene A/a and Gene B/b) AABB AABb AaBB AaBb AAbb Aabb aaBB aaBb aabb TALLEST SHORTEST Tall is dominant over short A = tallB = tall a = shortb = short Can combine polygenic inheritance with other non-mendelian genetics (most are), like incomplete dominance, to produce a range… Both genes are dominant 1 gene dominant 1 gene recessive Both rec. MEDIUM

3. Polygenic Inheritance w/ Inc. Dom. Several Genes (each with own alleles) determine ONE character (most polygenic are w/ inc.dom.) – –Two genes for Height (Gene A/a and Gene B/b) AABB AABb AaBB AaBb AAbb aaBB Aabb aaBb aabb TALLEST SHORTEST Incomplete Dominance! A = tallB = tall a = shortb = short Human skin color is also usually polygenic (have many different shades or skin tones) Most polygenies will involve 3 or more genes 4 tall alleles 2 tall alleles 0 talls 3 tall alleles 1 tall allele

4. What type of heredity? Incomplete Dom. 3 genes = 6 alleles = 7 phenotypes

5. Crazy Polygenic Inheritance Example Skin tone is polygenic  5 genes (each 2 alleles) – –Dark (A, B, C, D, E) dominant to light (a, b, c, d, e) How many different colors? DARKEST LIGHTEST Be able to determine range of traits if mix polygenic with inc.dom! Be able to do a dihybrid cross in the context of polygenic inheritance! Be able to do polygenic with multiple alleles… 5 genes = 10 alleles = 11 phenotypes

6. Pleiotropy: Pleiotropic Effects 1 allele of 1 gene will affect more than 1 phenotype – –This means 1 protein results in several visible traits   Single protein performs several jobs… Chromosome #7 cf gene Protein to make chloride transport channel work right Chromosome #7 mutant cf gene (recessive) Protein make chloride transport channel malfunction cf genotype: c c (characters)

7. Environmental Effects Environment can affect expression of gene – –Protein is made to work differently depending on environment   2 phenotypes (traits) from 1 genotype – –FF = white (when cold) – –FF = brown (when warm)

8. Nature vs. Nurture Controversy The phenotype you see may OR may not (only) be the result of genes – –Traits determined by genes (nature) – –Traits determined by environment (nurture) Examples – –Widow’s Peak – –Intelligence – –PKU disease (phenylketonuria) – –https://www.youtube.com/watch?v=1-_QKyipj_Yhttps://www.youtube.com/watch?v=1-_QKyipj_Y – –Black Aggression (Testosterone) Should you let your genes determine your fate?