1. Sex-Linked Traits
By: Lauren Beggs

2. Agenda 2/26/2013 Turn in 7.2 KT’s and questions 1-6
Incomplete Dominance Wkst
HW: Read 7.1, KT’s, and questions 1-5

3. Bellringer 2/26/2013 Shh! Don’t tell your answer.
Can you see a number in this picture? If so… what number do you see?

4. Estimated:
1/10 Caucasian males are colorblind
1/20 Caucasian females are colorblind.
Why is color-blindness
more prevalent in
males than in
females?

5. Sex-Linked Traits Mendel only studied traits on autosomes.
Autosomes: only contain genes unrelated to the sexual characteristics of an organism
Sex Chromosomes: contain genes that code for the sexual characteristics of an organism

6. Sex-Linked Traits Sex-Chromosomes
Females = XX
Males = XY
There are thousands more genes on the X chromosome than the Y chromosome.
Who determines the sex of the child? Mom or dad?
female
male

7. Sex-Linked Traits Mom Dad Diploid Parent Cell XY XX Haploid Gametes X

8. Sex-Linked Traits Egg Sperm #1 X X Offspring: XX Sex of the child?#2
Egg Y X XY
Offspring:
Sex of the child?

9. Sex-Linked Genes: Genes located on the sex chromosomes.

10. Sex-Linked Traits
Calico is coat fur color found in cats, which is caused by a SEX-LINKED, CODOMINANT allele.
B = Black
R = oRange
BR = calico
calico cat

11. Sex-Linked Traits Female genotypes, phenotypes? XBXB ______________
XBXR ______________
XRXR ______________
Male genotypes, phenotypes?
XBY ______________
XRY ______________
calico cat

12. Sex-Linked Traits Female genotypes, phenotypes? XBXB -- Black
XBXR -- Calico
XRXR -- Orange
Male genotypes, phenotypes?
XBY -- Black
XRY -- Orange
calico cat

13. A black male cat is crossed with an orange female cat.
Sex-Linked Traits
A black male cat is crossed with an orange female cat. x
Predict the phenotypes and genotypes of the offspring for both males AND females.

14. Sex-Linked Traits Male: XBY Female: XRXR x
Predict the phenotypes and genotypes of the offspring for both males AND females.

15. Sex-Linked Traits Male: XBY Female: XRXR XB Y XR XB XR Y XR XR x
100% Females = calico XR
100% Males = orange XR

16. An orange male cat is crossed with an calico female cat.
Sex-Linked Traits
An orange male cat is crossed with an calico female cat. x
Predict the phenotypes and genotypes of the offspring for both males AND females.

17. Sex-Linked Traits Male: XRY x Female: XRXB
Predict the phenotypes and genotypes of the offspring for both males AND females.

18. Sex-Linked Traits Male: XRY Female: XRXB XR Y XR XR XR Y XR XB XB Y XR
50% Females = calico
50% Females = orange
50% Males = orange
50% Males = black XR XB

19. …Food for Thought
If almost 10% of the population can’t differentiate between red & green…than why is the “stop” and “go” on a traffic light red and green?!