Assign Yourself: Sex Linked Practice

• Do Now:• Unit 2 Review 1 through 11 (yes, you may use

your homework)

Sex-Linked Inheritance

What is sex-linked inheritance?• Patterns seen when alleles for a trait are carried on

the X chromosome.

XA = X chromosome with dominant allele

Xa = X chromosome with recessive allele • Y chromosomes do NOT carry the alleles.

Processing Piece:• Draw a picture to illustrate sex-linked inheritance.• Find these on your paper:

XAXa XAY XaXa

XaY

• Label each one as a boy or girl.• Label each one as recessive or dominant trait.

What is a carrier?• A person who carries ONE allele for a recessive trait

but does NOT show the recessive trait.• Sometimes they’re shown on a pedigree like this:

= female carrier

Processing Piece:• Label the carriers.

XAXa XAY XaXa

XaY

Processing Piece:

On the pedigree below, label each person as XX or XY.

Circle X chromosomes with the recessive allele (Xa)

Processing Piece:What patterns do you notice? Who are the carriers?Who are the people affected?

What patterns are seen in sex-linked inheritance?

• Females who are carriers (heterozygous)• Males with the recessive trait

Sample Questions 1 through 3:1) Are most affected

individuals male?2) Are most carriers

female?3) Do you think this

is sex-linked inheritance?

Sample Questions 4 through 5:

4) Are most affected individuals male?5) Are most carriers female?6) Do you think this is sex-linked inheritance?

Sample Question 7A family has 2 parents, 1 son and 1 daughter. The father is colorblind (a sex-linked trait), and the mother does not carry any alleles for it. XN = normal Xn = colorblinda) What is the father’s genotype? _________b) What is the mother’s genotype? _________c) What must the daughters’ genotypes be?__________ d) What must the sons’ genotypes be? ______________e) Draw a pedigree of this family.

Sample Question 8A woman who is a carrier marries a man who has hemophilia. XN = normal Xn = hemophiliaa) Genotypes of the parents? _________ x _________ b) Draw a Punnett Square:

c) A boy who has hemophilia? ___d) A girl who is a carrier? ____e) A boy who does NOT have hemophilia? _______f) a girl who is NOT a carrier? ____

#4 on the classwork

Exit Ticket1) Which chromosome, X or Y, carries the alleles in

sex-linked inheritance?2) What are 2 patterns that are normally seen in

sex-linked inheritance?3) Draw an example of a pedigree you might see

for a sex-linked trait.

Assign Yourself: Draw and color completely (no white spots!) 2 parents and 2 dragon babies

• Do Now:• Unit 2 Review 12-23

Exit Slip

• Describe the pilot program that some schools in Kentucky participated in. Why was it started? Explain whether or not you think the program is a good idea and why. Support your response with information from the article.