Welcome Back Tracey has three brothers One of

Welcome Back! Tracey has three brothers. One of Tracey's brothers has sickle-cell anemia, a disease caused by a recessive allele. She, her parents, and the other children do not have it. If Tracey's parents have another child, what is the chance that the child will have sickle-cell anemia? A. 0% B. 25% C. 50% D. 75%

Going Beyond Mendelian Genetics r o l l Ta t r o h S

Bw X Bw = BB (25%) + Bw (50%) + ww (25%) Dominant (Black) Heterozygous (Black) Where did the grey mouse come from? Recessive (White)

Co-Dominance and Incomplete Dominance

Incomplete Dominance does not follow Mendel’s Rules Bb X Bb = BB (25%) + Bb (50%) + bb (25%) Dominant Incomplete Recessive

Bb X Bb = BB (25%) + Bb (50%) + bb (25%) According to Gregor Mendel: Genotypes: 25% BB 50% Bb 25% bb Phenotypes: 75% Black 25% White What about grey? !? !? !

Instead of writing it that way, we use a different capital letter for both. This is because neither is dominant over the other. BW X BW = BB(25%) + BW(50%) + WW(25%) B B BB B W W W BW Genotypes: 25% BB 50% BW 25% WW WW This ONLY works if the problem tells you its co or incomplete dominance. Phenotypes: 25% Black 50% Grey 25% White

Incomplete Dominance red x white ---> Pink A cross between organisms with two different phenotypes produces offspring with a third phenotype that is a blending of the parental traits.

Incomplete Dominance R = allele for red flowers W = allele for white flowers red x white ---> pink RR x WW ---> 100% RW

Incomplete Dominance

Co-Dominance Co: Together, or Shared Coexist- live together Co-dominance. The"recessive" & "dominant" traits appear together in the phenotype of hybrid organisms. red x white ---> Pink red x white ---> red & white spotted Co-Captains

Co-Dominance red x white ---> red & white spotted BOTH!!! R = allele for red flowers W = allele for white flowers red x white ---> red & white spotted RR x WW ---> 100% RW

What Do We Have Here? BB X WW BB- Black White- White Co-dominance: White and Black

What Do We Have Here? Theoretically…. . Beaver X Duck? Co-Dominance: Platypus

Incomplete Dominance Co-Dominance 1. Mixture 1. Traits 2. Blend seen rd 3. 3 or New “together” Phenotype

Bonus Material • sex-linked trait -A trait associated with a gene that is carried only by the male or female parent. Ex: In humans, the gene for colorblindness is carried by the X-chromosome.