1. Inheritance of Traits
Probability- the likelihood that a specific event will occur
When you flip a coin, there is a 50/50 chance it will land tails side up
If there are 4 kids in a family, probability says 2 will be girls and the other 2 will be boys

2. Inheritance of Traits
Carrier- an individual who is heterozygous for an inherited disorder but does not show symptoms.
Ex. Linda is a carrier for albinism.
Genotype-(Aa)
Phenotype- not albino
Even though she does not display the symptoms, she can still pass on albinism to her children.

3. Inheritance of Traits
Autosomal- when a gene is autosomal, it will appear in both sexes equally

4. Inheritance of Traits
Sex-linked- when a gene is sex-linked, it is found only on the X chromosome so the effects are seen in males more often than females
Remember, males are (Xy) and females are (XX)
Examples- colorblindness, hemophilia, Cystic Fibrosis and Sickle Cell Anemia

5. Inheritance of Traits Sex-linked Punnett Square for colorblindness: X
Key:
XX- female
Xy- male
Xby- colorblind male
XXb- female carrier
XbXb- colorblind female Xb y
What are the offspring?

6. Inheritance of Traits Sex-linked Punnett Square for colorblindness: XXb
Key:
XX- female
Xy- male
Xby- colorblind male
XXb- female carrier
XbXb- colorblind female X y
What are the offspring?

7. Inheritance of Traits Sex-linked Punnett Square for colorblindness: XXb
Key:
XX- female
Xy- male
Xby- colorblind male
XXb- female carrier
XbXb- colorblind female Xb y
What are the offspring?

8. XNXN XNXn XnXn XNy Xny Sex linked:
Sometimes you can write sex linked genotypes like this:
(N = normal; n= abnormal)
XNXN
XNXn
XnXn
XNy
Xny

9. Pedigrees
Pedigree- a family history that shows how a trait is inherited over several generations
Useful to track the carriers of genetic disorders in families
Can be used for both autosomal and sex-linked disorders

10. Pedigree Key Circle- female Square- male
Clear circle/square- does not show trait/disorder
Shaded circle/square- has trait disorder
Carries can be displayed several different ways:
half will be shaded
it will be clear with a line through the middle
it will be clear
Horizontal line between circle and square indicates two married people
Vertical line extending from a parent line leads to offspring
The order of children is left to right

11. Pedigrees Pedigree for albinism (autosomal): Key: Female Male
Female carrier
Male carrier
Female with albinism
Male with albinism
Married
with children
(P1)
(F1)
(F2)
*The order of children is from left to right

12. Pedigrees Pedigree for albinism (autosomal):C E F G H I J K
Which individuals are heterozygous for albinism?
Which are homozygous for albinism?
Which individuals have albinism?
Which generations have an individual with albinism?

13. Pedigree for colorblindness (sex-linked- X-linked Recessive Trait)

14. A F X
How many males are colorblind?
How many females are colorblind?
What is the genotype for square A?
What is the genotype for circle F?
Is circle F colorblind?
What is the genotype for circle X?

15. Complex Patterns of Heredity
We have been talking about “Mendelian Genetics” where the phenotype of one allele dominants over another
Now were are going to talk about “Non Mendelian Genetics”
Intermediate inheritance
Polygenic inheritance
Incomplete dominance
Codominance
Multiple alleles

16. Intermediate Inheritance
Intermediate inheritance- when the heterozygous offspring (Bb, Rr, etc) display a trait that is not exactly like either parent
One trait DOES NOT simply dominate over the other

17. Polygenic Inheritance
Many genes contribute to the phenotype
Provides genetic variation
Examples:
Skin color, hair color, height

18. Incomplete domiance R R r Rr Rr r Rr Rr
Incomplete dominance- when an individual displays an intermediate/middle phenotype of the parents (neither is dominate or recessive)
Ex. A red (RR) snapdragon flower is crossed with a white (rr) one and their offspring are pink (Rr) R R r Rr Rr r Rr Rr

19. Practice Incomplete dominance
Assume:
Red= RR
White = rr or WW or R’R’
Pink= Rr or RW or RR’
You cross a red flower with a white flower:
What happens?

20. Incomplete Domiance Cross a red flower with a pink flower
What happens? R R R RR RR r Rr Rr

21. Codomiance
Codominance- when two dominant alleles are expressed at the same time
Ex. Roan horses or cattle
have both red AND white hair

22. Codominance Practice You cross a red horse with a white horse: Assume:
Red= RR
White = rr or WW or R’R’
Red and White= Rr or RW or RR’
You cross a red horse with a white horse:
What happens?

23. Codominance Another example of codominance is blood type
If someone has AB blood that means they have both A blood AND B blood A A B AB AB B AB AB

24. Multiple Alleles
Multiple alleles- more than 2 forms of a gene are expressed
Example- rabbit coat color
It isn’t just black OR brown; brown OR white
Rabbit fur could be brown, black, white, or a combination of black and white

25. Multiple Alleles
Another common example of multiple alleles is blood type
IAIA = homozygous dominant A blood
IAIO = heterozygous dominant A blood
IBIB = homozygous dominant B blood
IBIO = heterozygous dominant B blood
IAIB = heterozygous but has both A and B blood (is also codominant)
iOiO = homozygous recessive

26. Practice Blood Type
If a man is homozygous for type B blood, and has a child with a homozygous woman with type A blood, what are the possible blood types of the child?
Phenotype
Genotype
Type A
Type B
Type AB
Type O
AA or AO (IAIA or IAiO)
BB or BO (IBIB or IBiO)
AB (IAIB)
OO (iOiO)

27. Practice Blood type
A man is heterozygous for type A blood and has a child with a woman that has AB blood. What are the possible blood types of the child?
Phenotype
Genotype
Type A
Type B
Type AB
Type O
AA or AO (IAIA or IAiO)
BB or BO (IBIB or IBiO)
AB (IAIB)
OO (iAiB)