1.write the possible gametes in the following parent: aabbcc (notice: one allele per gamete for each...
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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?