1. How could a type A blood and type B blood parent have type O blood children?

2. Multiple Alleles
Definition: Genes (trait) with 3 or more alleles. Examples: Blood type

3. Multiple Alleles A Blood Type B Blood Type O Blood Type
If these three alleles (A,B, and O ) were all possibilities to be matched up in a pair, what would be all the possible combinations?

4. Phenotype (Blood type)
Multiple Alleles
Phenotype (Blood type)
Genotypes A
____________ OR ___________ B
_____________ OR ___________ AB
______________ O
_______________

5. AO= A blood type Which allele would be considered dominant? Recessive?
What is the phenotype?
Is this combination
Heterozygous or
homozygous?

6. BO= B Blood Type
Which allele would be considered dominant?
Recessive?
Is this combination
heterozygous or
homozygous?

7. OO= O Blood Type
Is this Homozygous Dominant or Recessive?

8. AB= ? Blood Type
Based on what happened in the basketball game, which allele would be considered dominant?
What would be the blood type?
What do we call this match up
(Remember Friday's lesson?)

9. AA= Blood type A BB= Blood type B
Multiple Alleles
AA= Blood type A BB= Blood type B

10. Blood type chart

11. Multiple Alleles
How is this genetic scenario different from what we have seen in the past?
How is this similar to what we have seen?

12. Practice Problem
A woman with type A blood (genotype AO) is married to a type B person (genotype BO). What proportion of their children will have: _________ x ________ A blood? ______ B blood? ______ O blood _______ AB blood ______

13. Multiple Alleles
Blood type

14. Blood types

15. Why are traffic lights always on the same orientation?

16. Are you color blind?

17. Here are the stats:
About % of men in America are diagnosed to be color blind. About 1 out of 100 female are diagnosed to be color blind. The most common colors for blindness are red and green.

18. SO, Why are men more likely to be colorblind than women?

19. Sex- Linked Traits
Definition: Trait whose allele is located on the X chromosome

20. Girl
XX—Sex Chromosomes

21. Boy
XY—Sex Chromosomes

22. Types of Sex C’somes X chromosome –
found in women and men, much larger in size
Y chromosome –
found ONLY in men, much smaller

23. Punnett Square with Sex Chromosomes
Fill in your Punnett square
As always, it doesn’t matter which genotype you put on the top or the side, this could be switched and you would still get the same result. X Y XX XY X XX XY X
Ratio of male to female?
50:50 or 1:1
In a population, ~ ½ of the zygotes (embryos) are male, and ½ are female
k. malone ©2005

24. Sex Linked Genes
Genes located on chromosomes X and Y are called Sex Linked genes
Many sex linked genes are found on the X and very few are found on the Y (much smaller!)
Colorblindness- 2 of the 3 human genes for color vision are located on the X, and males with a defective version of any 1 of these genes will have colorblindness
Why?
Males = XY, only one copy of X, whatever is on that X is expressed
Colorblind male = XcY
Normal male = XCY
k. malone ©2005
Normal carrier female = XCXc
Colorblind female = XcXc
Normal female = XCXC

25. Sex Linked cont… The X chromosome (genes) codes for over 2300 traits.
There are only a few genes that codes for traits on the Y chromosomes.
Male: XY
Female: XX
Who has a higher
Chance of getting the
X-linked disorder?
k. malone ©2005

26. X-linked genes Since males have just one X chromosome.
Therefore, all X-linked alleles (good or bad) are expressed in males, even if they are a recessive trait.
k. malone ©2005

27. XhY XHXh
What is different from genotypes we have already seen? What is similar? If “H” was normal, and “h” had hemophilia, what phenotype would this boy have?

28. Sex-linked cross

29. Example of a Sex-linked Cross
On which chromosomes are the genotypes attached?

30. Other sex-linked traits: Hemophilia
A sex linked disorder found on the X-c’some that does not code for the protein necessary to clot blood

31. Genotype =
Phenotype =