1. Today we are learning sex-linked traits
The sex-linked traits. You can find them here!

4. Sex Chromosomes
Key Point #1 – Sex (gender) chromosomes determine if you are male or female
XX = female
XY = male

5. Sex Linked Traits Key Point #2:
MOST Sex linked traits are found on the X chromosome only (in college bio you may look at some Y linked traits, but not in here!)
The Y chromosomes is too small to carry the information
I think that it is true that diseases can be on the Y chrosmoes, but they are very very rare and would never show up on the EOC or GEE, so I think that we should stick with saying that the Y chromosomes doesn’t really have any informaiton on it. 5

6. Sex Linked Traits Key Point #3
Women need two X chromosomes with a bad gene to have a sex-linked trait
Men only need one X chromosomes with a bad gene to have a sex-linked trait
I say bad because most sex-linked traits are diseases (sorry boys!)  but not ALL!

7. Sex-linked recessive traits!
We are doing doing X-linked recessive traits
XH = dominant Healthy
Xh = recessive sick
Y = neither (does not carry any h’s)

8. TO DO PS problems, we need to know genotypes and phenotypes!
H=healthy
h=sick
What are carriers?
-carries a copy of the
Recessive allele
Do you see any male
carriers?
Phenotype
Genotype
Healthy female
XHXH
Carrier female
XHXh
Sick female
XhXh
Healthy boy
XHY
Sick boy
XhY

9. GP 1 Healthy or Sick? Healthy is dominant 1. XH Xh 2. Xh Y 3. XH Y

10. This next example is for….
HEMOPHELIA
a disease where your blood doesn’t clot

11. GP-2 XH=healthy Xh=hemophilia Carrier female + healthy man! XH XH Y Xh
What % of the children are girls?
What % will be boys?
What % will have hemophilia?
What % of kids will be healthy?
XH Y XH Xh
XHXH
XHY
XH Xh
XhY

12. GP-3
What makes something sex-linked rather than just a regular trait?

13. GP-4
Are males or females more susceptible (likely to be affected) to sex-linked diseases?

14. GP-5 Healthy female + sick man! XH Xh Y XHXh XHY XH Xh XHY
What % of the children are girls?
What % will be boys?
What % of the kids will have hemophilia?
What % of kids will be healthy?
Xh Y XH
XHXh
XHY
XH Xh
XHY

15. GP-6 Carrier female + sick man! XH Xh Y XHXh XHY Xh Xh XhY Xh
What % of the children are girls?
What % will be boys?
What % of the kids will have hemophilia?
What % of kids will be healthy?
Xh Y XH Xh
XHXh
XHY
Xh Xh
XhY

16. Who are the parents?!?!

17. Scenario 1
Katie is a carrier for alopecia (baldness). Her baby is not growing any hair at all. She is not sure if Richard, her husband, or Adam, her husband’s best friend, is the father…
Richard’s genotype is XhY
Adam’s genotype is XHY

18. XHXH XHY XHXh XhY XhXh XhY Adam Richard XH Y Xh Y XHXh XH XH Katie Xh

19. Scenario 2
Samantha has hemophilia blood and so does her baby. She is not sure whether Nick or Ron is the father of her baby….
Nick is a hemophiliac
Ron is not
Which one is the father? Use Punnett Squares to prove it. 19

20. WE DON’T KNOW! Either can be the father!
Nick
Ron Xh Y XH Y
XhXh
XhY
XHXh
XhY Xh Xh
Sam
XhXh
XhY
XHXh
XhY Xh Xh

21. Scenario 3
Jackson is color-blind (a sex-linked trait). His mother is not a carrier for this trait but his father is incapable of differentiating between red and blue.
What does this mean?! (Prove your answer with a Punnett Square!)

22. JACKSON IS ADOPTED XH XH XH Xh
XH Xh Xh
Jackson is XhY Y XH Y XH Y

23. What goes in my folder? Quiz Last night’s homework Worksheet Exit slip
Reminders: DOLL HAIR!

24. Practice