1. Picture of your chromosomes
Karyotype-
Picture of your chromosomes
Humans have 23 pairs of chromosomes.
One pair of chromosomes is related to the sex of an individual , these chromosomes are called sex chromosomes

2. Picture of your chromosomes
Karyotype-
Picture of your chromosomes
The other 22 pairs of chromosomes are called autosomes (1-22)

3. Which parents determines the sex of their offspring?
DAD
Why?
All moms have the genotype XX. When egg cells are made, they will all carry a single X chromosome. All dads have the genotype XY, so half their sperm carry X and the other half carry Y

4. Sex Chromosomes
In humans, the sex of an individual depends on the presence or absence of the Y chromosome
A normal human female is XX
A normal human male is XY

6. Sex Linked Genes
Those traits that are controlled by genes on the X or Y chromosomes.
NOTE: The Y chromosome is much smaller than the X chromosome and only contains a few genes. Most sex-linked traits are on the X chromosome.

7. (b = colorblind, B = normal)
Sex Linked Traits
Traits determined by sex-linked genes are called sex-linked traits
 (b = colorblind, B = normal)
Ex. Color blindness
female Xb Xb
male Xb Y

8. Sex Linked Traits
Sex linked traits are recessive, this means both X chromosomes must have the gene in order for the trait to be expressed in females.
In males, however, they only need it to be on their one X in order for the trait to be expressed.

9. Missing all the corresponding chromosomesX X X Y
Since there are TWO X’s in females, the dominant gene can always mask the corresponding recessive gene
Since there is only ONE X in males, there isn’t a corresponding gene for most of the genes, so nothing can mask the gene if it is on the X chromosome. They only get that one gene and it always will show
Missing all the corresponding chromosomes
FEMALE
MALE

10. (B= normal, b= colorblind)
Carriers
A carrier is a person that has the trait on only one chromosome and does not express the trait. Carriers of sex linked traits are ALWAYS women.
(B= normal, b= colorblind)
Ex. Color blind carrier XB Xb

11. Sex Linked Punnett Squares
A colorblind male marries a homozygous normal female. What are the offspring genotypes and phenotypes? (B = normal, b = colorblind)
Xb Y XB

12. Sex Linked Punnett Squares
A colorblind male marries a normal female. What are the offspring genotypes and phenotypes?
(B = normal, b = colorblind)
Xb Y
XB XB Xb XB Y
XB XB Xb XB Y

13. Sex Linked Punnett Squares
A normal male (not colorblind) marries a carrier. What are the offspring genotypes and phenotypes?
XB Y XB Xb

14. Sex Linked Punnett Squares
A normal male (not colorblind) marries a carrier. What are the offspring genotypes and phenotypes?
XB Y
XB XB XB XB Y
Xb Xb Xb Xb Y

15. Sex Linked Punnett Squares
A normal male (not colorblind) marries a colorblind female. What are the offspring genotypes and phenotypes?
XB Y Xb

16. Sex Linked Punnett Squares
A normal male (not colorblind) marries a colorblind female. What are the offspring genotypes and phenotypes?
XB Y
Xb XB Xb Xb Y

17. Other X-linked traits Muscular Dystrophy Fragile-X syndrome
Night Blindness
Male pattern baldness
Hemophilia**

18. Hemophilia Hemophilia is characterized by uncontrolled bleeding
It is a sex linked disorder caused by errors in the DNA that codes for the proteins involved in clotting