1. Write the possible gametes in the following parent: AaBbCc (notice: one allele per gamete for each genes: ABC, Abc, …)

2. Repeat your answer considering the position of the genes on the chromosomes:

Assort Independently: A and C; B and CDo NOT assort Independently: A and B - they are on the same chromosome.

This will affect the ratios between the phenotypes in F2 generation…

John Isabelle

Liz

SueDan

Lucy

LukeJoshua PhilWhat is the relationship between:Dan-Sue; Luke-Joshua; Phil-Isabelle; Liz-Dan; Joshua-Sandy?

Sandy

marriage

children

John Isabelle

Liz

Dan Sue

Lucy

LukeJoshua Phil

Sandy

carriersaffected

unaffected

Is the disorder carried by a dominant or recessive allele? Explain your answer, add genotypes

Copy the pedigree.

(Question 5)

Is the disorder carried by a dominant or recessive allele? Explain your answer.

Copy the pedigree.

Answer: The disorder is Recessive, since it ‘skipped a generation’. ‘Normal’ parents must be heterozygous carriers.

Autosomal Vs. Sex-linked Disorders:

Sex-linked disorder = Gene is on a sex chromosome (mostly on the X)Autosomal disorder = Gene is on any of the other 1-22 chromosomes.Dominant vs. Recessive Disorders:Dominant disorder = carried by the dominant allele. Recessive disorder = carried by the recessive allele.

Several Genetic disorders are inherited in genes that are located on the X chromosome.Predict: Who do you expect will show these disorders more often, females or males? Explain.

Women are XX, men are Xy

Sex-linked Inheritance

Definition: Sex-linked genes are located on the sex chromosomes, usually on the X chromosome.

So, why is this important?

Dystrophin (Duchenne MS)

Clotting Factor(Hemophilia A)

Color Receptor (Red/Green)

“Royal” Disease - Hemophilia

Adiel (1986-1999)

46XX 46XY

Female Male

A recessive X-linked disorder has a better chance to show in males. Example: Color Blindness. C = normal c = colorblind

Cross: 1) XCXc x XCY2) XCXC x XcY x

x

1) XCXc x XCY x

XC

XC

Xc

Y

XCXc

XCXC

XcY

XCY

Daughters: 0% color-blindSons: 50% chance to be color-blind

2) XCXC x XcYXC

XC

XC

Y

XCXc

XCXc

XCY

XCY

Daughters: 100% To be a carrierSons: 0% chance to be color-blind

x

In Conclusion: 1) X-linked Disorders are more

common amongst males. Reason:_________________

2) Can a colorblind man pass the disorder to his son?

Answer:___________________

http://www.kcl.ac.uk/teares/gktvc/vc/lt/colourblindness/plate1.htm

About Sickle Cell Anemia•Caused by a mutation in the gene for Hemoglobin, which delivers oxygen in the blood.

•Symbols: HA= Normal hemoglobin.HS = Mutated hemoglobin.- The same symbols are used for the corresponding alleles.

Sickled

Red Blood Cells

Normal

Why does this happen?Normal (with Valine)

Mutated (with Glutamic Acid)

Traffic Jams by sickled cells

Add punnet square for sickle cell with HA and HS, and with corresponding phenotypes.

Abundance of the S Allele in Malaria-infested regions.

Normal and Sickle hemoglobin proteins migrate differently in a gel: normal is more negative. What kind of hemoglobins are for each persons 1, 2 and 3? (Alleles: H is normal and Hs is sickled)

In a genetic test of this family, the mutated and normal proteins were analyzed. Is the disease recessive or dominant? Explain.

1. 2. 3. 4.

-

+

A rare unknown disorder causing deafness was found to be common in one family.

affectednot affected

Some disorders we learned about are very harmful, even deadly.

Why, then, do they still exist in the population?