Complex Patters of Inheritance 11 2 Independent Assortment

Complex Patters of Inheritance 11 -2 Independent Assortment Inheritance Patterns Beyond Simple Dominance

Quick Review o. Allele: each letter (R or r) n Dominant masks Recessive (Rr or rr) o. Law of Dominance? o. Homozygous RR/rr o. Heterozygous Rr

Law of Independent Assortment o States that genes for different traits can segregate independently during meiosis o Gives many more genetic variations o MEANING: If a pea plant is yellow and wrinkled < Rr. Yy>, both sets of alleles will separate independently (they work alone!) o An offspring can receive any combination of r’s and y’s

Dihybrid Crosses Used For Proof

Sex-Linked Traits o Traits controlled by genes on the X chromosome. (X-linked traits) o Ex: Red-green color blindness and Hemophilia o It is a recessive X-linked trait.

Sex Determination § Sex chromosomes determine an individual’s gender.

Incomplete Dominance o. Dominant and Recessive Blend in a heterozygous genotype o. Ex: Flower Color o. Red (RR) Flower X White (rr) Flower =PINK (Rr) o. Can you think of other examples?

Co dominance o No recessive, Both traits expressed o Ex: coat color o Heterozygous will both be capital letters because both dominant!

RR=Black, WW=White, RW=Black and White Bunny

Other Ways To Show Genotypes o Use 2 different letters (all caps) o Ex: BW=black and white bunny o Use apostrophes to show the other allele o Ex: RR = red R’R’ = white RR’=Roan o (Roan= both) o Found in cows, horses, dogs, etc

Examples of Roan Animals (co-dominant coat color)

Multiple Alleles o Genes with 3 or more alleles o Ex: Blood Typing o 3 alleles = IA, IB, i o Give 4 possible phenotypes: n n A (IAIA, IAi) B (IBIB, IBi) AB (IAIB) O (ii)

Here’s How… AA= A Ai = A BB = B Bi = B AB= AB ii = O

Epistasis o One allele hides the effect of another allele. o Ex: Labrador’s coat color is controlled by 2 sets of alleles. o The dominant allele “E” determines whether the fur will have dark pigment. Eebb, Ee. Be o Black and Chocolate vs White and Yellow.

Polygenic Trait o Several Genes Influence a Trait o Ex: Skin, Weight, Eye Color, Height o Most genes scattered along the same chromosome o What causes so many variations?

Traits Influenced by Environment o Phenotypes can change based on environment o Ex: Hydrangea Color o Fur in mammals (color and thickness) o Height and weight in humans based nutrition