1. Unit 7
Genetics

2. Incomplete and Co-dominance Crosses
Day 3
Incomplete and Co-dominance Crosses

3. Incomplete Dominance
If two genes are equally dominant for a trait, both will show up
(NO DOMINANCE)
Phenotype is blended
Heterozygote is written as either big letter small letter, with an apostrophe, or with “exponents”

4. Incomplete Dominance

5. RR= Red R’R’= White RR’= Pink
Cross a hybrid with a red
RR’ x RR R R’ RR
RR’
Genotype Phenotype
RR- 50%
RR’- 50%
Red- 50%
Pink- 50%

6. RR= Red R’R’= White RR’= Pink
Cross two Hybrid flowers
RR’ x RR’ R R’ RR
RR’
R’R’
Genotype Phenotype
RR- 25%
RR’- 50%
R’R’- 25%
Red- 25%
Pink- 50%
White- 25%

7. Codominance Both alleles contribute to the phenotype
Both are shown equally
Ex: chicken with black and white feathers or roan cows

9. BB= Black BW= Speckled WW= White
Cross a hybrid chicken with a white chicken
BW x WW B W BW WW
Genotype Phenotype
BW- 50%
WW- 50%
Speckled- 50%
White- 50%

10. Multiple Alleles and Blood Types
Day 4
Multiple Alleles and Blood Types

11. Multiple Alleles More than 2 alleles for the trait
No more than 2 alleles can be present in a cell
Ex: Blood (A, B, and O are codominant)

12. Blood Types Landsteiner- discovered blood types
Drew- discovered plasma and was in charge of the blood bank in WWII
Harvey- discovered the path that blood circulates through the body

13. Positive and Negative? Rh factor- protein on blood cells
Positive- the Rh factor is present
Can receive either positive or negative blood
Negative- the Rh factor is absent
Can only receive negative blood
If receive wrong blood type, blood will attack.

14. 4 Blood Types A B AB O IAIA IBIB -- ii IAi IBi IAIB A protein
Homozygous
Heterozygous
Antigen
Donor
Recipient A B AB O
IAIA
IBIB -- ii
IAi
IBi
IAIB
A protein
B protein
A& B protein
NONE
To A ONLY
To B ONLY
To AB ONLY
ALL
A or AB
B or AB
A,B, AB, O
O ONLY
Universal Donor= O
Universal Recipient= AB
Antigen- protein marker on the surface of the red blood cell

16. Practice Problem #1 Cross male type AB with female homozygous A
IAIB x IAIA IA IB
IAIA
IAIB
Genotype Phenotype
IAIA- 50%
IAIB- 50%
A- 50%
AB- 50%

17. Who’s baby is it?
At the hospital, 2 babies were accidentally mixed up, and the parents didn’t know which baby belonged to whom. The blood groups of everyone involved is listed below. Determine which baby belongs to which couple. Baby 1 – Type A Mr. Brown – Type AB Baby 2 – Type O Mrs. Brown – Type B Mr. Smith – Type B Mrs. Smith – Type B
Baby 1 must belong to Mr. and Mrs. Brown – they could not create a Type O (ii) baby, because only one parent could possibly contain the i allele
Baby 2 must belong to Mr. and Mrs. Smith – they could not create a Type A (IAIA, IAi) baby, because neither carries the IA allele

18. Which child is adopted?
The Tyler family has three kids, one of which is adopted. The blood types of the parents and children are listed below. Determine which child is adopted. Mom – Type AB John – Type B Dad – Type O Martha – Type AB Zackary – Type A
Martha (IAIB) is adopted: Dad is Type O (ii) and could not have given either of her two alleles