1. Heredity not following the Rules

3. Incomplete dominance
A heterozygous condition in which both alleles are partially expressed, often producing an intermediate or blended phenotype (which is different than either of the homozygous forms).
Snapdragons

4. Incomplete dominance Both traits are "weak"
and not strong enough alone,
so they blend their strengths to make a new color.
Snapdragons

5. Incomplete dominance RR R’R’ RR’ RR RR’ RR’ R’R’ In Incomplete
use the SAME
letters since they
both are weak!
Incomplete dominance RR
R’R’
RR’ RR
RR’
RR’
R’R’

6. Incomplete dominance H’ H’ H H
Palomino horses are a cross between a chestnut horse and a cremello (white) color horse.
Practice the cross using a Punnet Square. H’ H’
HH’ H H

7. Co – both are dominant enough to be expressed!!
Codominance
Codominance –Neither phenotype is dominant. Instead, the individual expresses both phenotypes.
Co – both are dominant enough to be expressed!!
Dominique chickens

8. Predict the outcome if BOTH chickens are dominique
In CODOMINANCE,
use DIFFERENT
letters since they
both are strong!
Codominance
BB - Black
WW - White
BW - Black and White W W
Predict the outcome if BOTH chickens are dominique
(black and white) ???? BW
Cross a black chicken with a white chicken and what to you get if the traits are CODOMINANT? B B

9. BB=1 BW=2 WW=1 Codominance B W B W BB BW WW BB - Black WW - White
BW - Black and White B W BB BW WW B
BB=1
BW=2 W
WW=1

10. Codominance
Another example of codominance is ABO blood typing. The blood types A and B are codominant to each other; however, type O is actually recessive to A and B.

11. When both alleles exist,
Codominance
BB or BO OO AB
AA or AO
When both alleles exist,
both are present!

12. Codominance Universal recipient Universal donor Blood Group Antibodies
Which group is the
universal recipient?
Which group is the
universal donor?
Codominance
Blood Group
Antibodies
Can give blood to…
Can receive blood from AB
None
A, B, AB, and O A B
A and AB
A and O
B and AB
B and O O
A and B
Universal
recipient
Universal
donor

13. Practicing Blood Types
A man of blood type AA marries a woman with blood type AB. What is the chance they will have a child with type AB blood? A B AA AB A
AB? A

14. Practicing Blood Types #2
There could be
2 genotypes
for the man:
BB or BO
Practicing Blood Types #2 O?
A man of blood type B marries a woman with blood type O. What is the chance they will have a child with type O blood? O O O O BO BO OO B B
50% 0% B O

15. Multiple Alleles Why can you only have 2 genes for each trait?
An individual can only have 2 genes thus 2 alleles for a trait, but there could be more than 2 alleles present in a population. This type of inheritance is known as multiple alleles.
Why can you only have 2 genes for each trait?
Because… you only have 2 of each type of chromosome!!

16. Multiple Alleles - examples
In Blood typing, there are 2 possible alleles (genes) that could could inherit – A, B, and O, but you can only inherit 2 of them. In this case, blood typing is also a trait that has multiple alleles.
Coat color in rabbits is inherited as a series of multiple alleles.

17. Multiple Alleles - examples
How many alleles
are there for
rabbit coat color? 4

18. Multiple Alleles - examples
Why is dark gray
a capital C?
What are all of the possible genotypes for a
dark-gray coated rabbit? (4)
CC Ccch Cch Cc
chinchilla rabbit (3)
cchcch cchch cchc
Himilayan rabbit(2)
chch chc
White rabbit (1) cc

19. Multiple Alleles - examples
Predict the phenotype for a rabbit with a cchch.
Chinchilla
Is it possible to obtain a white rabbit if one parent is white and the other is chinchilla?
Yes. Only if the chichilla is cchc

20. Polygenic Inheritance
Polygenic inheritance is the inheritance pattern of a trait that is controlled by two or more genes. The genes may be on the same chromosome or on different chromosomes.
Height in humans
Skin color

21. Polygenic Inheritance
Gametes
 ABC 
 ABc 
 AbC 
 Abc 
 aBC 
 aBc 
 abC 
 abc 
ABC 6 5 4 3
ABc 2
AbC
Abc 1
aBC
aBc
abC
abc
Polygenic inheritance in people showing a cross between two mulatto parents (AaBbCc x AaBbCc). Skin color has now been determined that it is controlled by 3 different genes. The offspring contain seven different shades of skin color based on the number of capital letters in each genotype.
Skin color

22. POPQUIZ!! (Just kidding)
A roan cow is the product of a red cow and a white cow. What type of inheritance is exhibited?
Complete dominance
Codominance
Incomplete dominance
Sex-linked
Multiple alleles
Polygenic B

23. POPQUIZ!!
Curly headed people have the genotype HH, while straight headed people have the genotype hh. A wavy headed person is heterozygous. What type of inheritance does this exhibit?
Complete dominance
Codominance
Incomplete dominance
Sex-linked
Multiple alleles
Polygenic C

24. POPQUIZ!!
How well a person performs on an IQ test is controlled by multiple genes. Which of the following types of inheritance does this exhibit?
Complete dominance
Codominance
Incomplete dominance
Sex-linked
Multiple alleles
Polygenic F

25. POPQUIZ!!
Hair loss is a trait caused by a gene located on the X chromosome. This trait would be considered -
Complete dominance
Codominance
Incomplete dominance
Sex-linked
Multiple alleles
Polygenic D

26. POPQUIZ!!
Kim’s has always wondered why her 2nd toe is longer than her first. She recently discovered that it is a dominant trait. This trait is considered to exhibit -
Complete dominance
Codominance
Incomplete dominance
Sex-linked
Multiple alleles
Polygenic A

27. BTW

28. POPQUIZ!!
Here is an easy one! Blood types fall under the category of which type of inheritance?
Complete dominance
Codominance
Incomplete dominance
Sex-linked
Multiple alleles
Polygenic E A B
HEE HEE