Cross a homozygous dominant green plant with a heterozygous green plant. What are the genotypic and phenotypic ratios. Agenda for Monday April 11 th 1. Complex patterns of inheritance – Incomplete and Co-dominance

Incomplete Dominance Complete dominance: a heterozygous individual’s phenotype will show the dominant trait When red snapdragons (RR) were crossed with white snapdragons (rr) offspring were pink (Rr)

Incomplete Dominance one allele for a trait is not completely dominant over the other allele Combined phenotype (blended) R = allele for red flowers W = allele for white flowers red x white ---> pink RR x WW ---> 100% RW

Co-dominance In COdominance, the "recessive" & "dominant" traits appear together in the phenotype of hybrid (heterozygous) organisms

Practice Set up genotypes for the phenotypes listed in each set. Remember that the "medium" trait is always heterozygous. a) Birds can be blue, white, or white with blue-tipped feathers. b) Flowers can be white, pink, or red. c) A Hoo can have curly hair, spiked hair, or a mix of both curly and spiked. D) A Sneech can be tall, medium, or short.

1. Write the genotypes for the pictured phenotypes 2. Show the cross between a star-eyed and a circle eyed. What are the phenotypes of the offspring? What are the genotypes?

3. Show the cross between a circle-star eyed, and a circle eyed. How many of the offspring are circle-eyed? How many of the offspring are circle-star eyed? Write the genotypic and phenotypic ratios. 4. Show the cross between two circle-star eyed. How many of the offspring are circle-eyed? How many of the offspring are circle-star eyed? How many are star eyed?

Agenda for Thursday April 14 th 1. Sex Linked Traits Quiz tomorrow – words 83 – 90 In humans, straight hair (ss) and curly hair (cc) are co- dominant traits that result in hybrids that have wavy hair (sc). Cross a Straight hair female with a wavy haired male. What are the chances of having a curly haired child? What are the chances of having a straight hair child? What are the chances of having a wavy hair child?

Sex Determination Thomas Hunt Morgan – studied fruit flies in the early 1900’s

Sex Determination Observed that one pair of chromosomes was different between males and females – Large one named “X” chromosome – Smaller one named “Y” chromosome – XX = female; XY = male

XY XX X Y X X X X X Y Female XX Female XY Male XY Male 50% Female; 50% Male

Sex Linkage Sex Linkage: the presence of a gene on a sex chromosome (X or Y)

Sex Linkage X-linked genes: genes found on the X chromosome – X chromosome carries more genes Y-linked genes: genes found on the Y chromosome

Fruit Fly Eye Color Fruit flies normally have red eyes A few males have white eyes Red is dominant; white is recessive

Morgan’s Fruit Fly Experiments Red-eyed female (X R X R) x White-eyed male (X r Y) XRXR XRXR XrXr Y XRXrXRXr XRXrXRXr XRYXRYXRYXRY RESULTS: F 1 generation – all red-eyed

Morgan’s Fruit Fly Experiments Red-eyed female (X R X r) x Red-eyed male (X R Y) XRXR XrXr XRXR Y XRXRXRXR XRXrXRXr XRYXRYXrYXrY RESULTS: F 2 generation – 3 red-eyed and 1 white- eyed ** all white-eyed where males…why?

Morgan’s Conclusions Gene for eye color is carried on the X chromosome = eye color is an X-linked trait Y chromosome does not carry a gene for eye color Red-eyed = X R X R, X R X r, X R Y White-eyed = X r X r, X r Y

Agenda for Friday April 15 th 1. Quiz 2. Multiple alleles In fruit flies red eye color (R) is dominant to white eyes (r). Cross a heterozygous female with a white eye male. What are the phenotypic and genotypic ratios?

What is meant by sex-linked trait? Agenda for Monday April 18 th 1.Re-do quiz 2.Sex-linked traits worksheet

In humans colorblindness (b) is an example of a sex-linked recessive trait. A male without colorblindness marries a female who isn’t colorblind but carries the allele. 1.What are the phenotypes of the offspring? 2.What are the genotypes of the offspring? 3.What are the genotypic ratios? 4.What are the phenotypic ratios? 5.What is the percent chance of each genotype? 6.What is the percent chance of each phenotype?

Agenda for Tuesday April 19 th 1. Sex linked traits practice In humans colorblindness (b) is an example of a sex-linked recessive trait. A male with colorblindness marries a female who isn’t colorblind but carries the allele. 1.What is the percent chance of each genotype? 2.What is the percent chance of each phenotype?

In fruit flies red eye color (R) is dominant to white eyes (r) and is a sex linked trait. A heterozygous red eye female mates with a red eye male. 1.What are the phenotypes of the offspring? 2.What are the genotypes of the offspring? 3.What are the genotypic ratios? 4.What are the phenotypic ratios? 5.What is the percent chance of each genotype? 6.What is the percent chance of each phenotype?

Agenda for Wednesday April 20 th 1. Go over worksheet 2. Multiple alleles In fruit flies red eye color (R) is dominant to white eyes (r) and is a sex linked trait. A heterozygous red eye female mates with a white eye male. 1.What is the percent chance of each genotype? 2.What is the percent chance of each phenotype?

Epistasis Epistasis – when one allele hides another Labrador Coat Color – 2 alleles – Dominant allele E determines pigment ee will have no pigment – Dominant allele B determines how dark the pigment EEbb or Eebb = chocolate brown eebb, eeBb, or eeBB will be yellow because e masks effects of dominant B allele

Multiple Alleles Multiple alleles – traits that are determined by more than 2 alleles – We have only 2 alleles (1 from mom, 1 from dad) – Blood groups (ABO) – O is recessive (i allele) ALLELE I A I B i CODES FOR Type "A" Blood Type "B" Blood Type "O" Blood

GENOTYPES I A I A I A i RESULTING PHENOTYPES Type A Type A IBIBIBiIBIBIBiType B IAIBIAIB Type AB iiType O

More alleles means more combinations there are 6 different genotypes & 4 different phenotypes for blood type Note: 2 genotypes for both "A" & "B" blood --- either homozygous (I A I A or I B I B ) or heterozygous with one recessive allele for "O" (I A i or I B i). Note too that the only genotype for "O" blood is homozygous recessive (ii). And lastly, what's the deal with "AB" blood? What is this an example of? The "A" trait & the "B" trait appear together in the phenotype.

Problems A woman with Type O blood and a man who is Type AB have are expecting a child. What are the possible blood types of the kid? What are the possible blood types of a child who's parents are both heterozygous for "B" blood type?

One More What are the chances of a woman with Type AB and a man with Type A having a child with Type O?