Genetic Disease 4

Assignment #2 – Patterns of Inheritance

First: Answer the following question.

Which disease types, autosomal dominant or autosomal recessive are generally more common / persistent in populations? Explain your answer.
(Please do not guess or otherwise invent your answer! Rather, do some research and reading, i.e. Chap. 14!)

Sickle cell disease is a autosomal recessive trait that occurs due to the single base substitution in DNA.

Second: Demonstrate this principle by showing the population proportions for autosomal recessive and dominant diseases below.

A: Autosomal Recessive Disease.

Do Punnett squares for the three possible crosses of the parents shown without doing 'back-crosses' (i.e. do not cross, (aa x aa), (Aa x Aa) , or (AA x AA) )

Parents = AA, Aa, aa

A a A
AA
Aa a aA aa A
A
a
AA
aa a aa
AA

A
A
a
Aa
aa a
Aa
aa

Circle, highlight or otherwise mark all individual genotypes that will be afflicted with the disease.

2. What is the overall percentage (or proportion) of F1offspring in this population that have this autosomal recessive disease ? Sickle cell is recessive disease which affects about 1 in 500 babies among the black and latin americans. q^2 is 1/500 or 0.002. q is sq root or 0.01 so answer is 0.01 or (1%).

1. Imagine that the disease type above is lethal or otherwise reduces survival and reproductive potential. In this case, are there any individuals within the population model above that will produce afflicted offspring in subsequent F2 generations?

100% of offsprings are AA (dominant) _____________________________________________________________________________

B: Autosomal Dominant Disease.

Repeat Punnett squares for the three possible crosses of the parents shown without doing 'back-crosses'. Parents = AA, Aa, aa

A a A
AA
Aa a aA aa 



A
A
a
AA
aa a aa
AA

A
A
a