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Associate Program Material

Genetics Worksheet

Review the images below and answer the follow-up questions. Each question is worth 20 points. Key:
Male affected with cystic fibrosis
Unaffected male
Female affected with cystic fibrosis
Unaffected female
Generation
I
II
III
IV
V
Pedigree showing inheritance of cystic fibrosis
A
Key:
Male affected with cystic fibrosis
Unaffected male
Female affected with cystic fibrosis
Unaffected female
Generation
I
II
III
IV
V
Pedigree showing inheritance of cystic fibrosis
A

Questions:

1. According to the pedigree, is cystic fibrosis inherited as a dominant or as a recessive traitKey: Male with Huntington’s disease
unaffected male
Female with Huntington’s disease
unaffected female
Generation
I
II
III
IV
V
Pedigree showing Inheritance of Huntington’s disease
Key:
Male with Huntington’s disease
unaffected male
Female with Huntington’s disease
unaffected female
Generation
I
II
III
IV
V
Pedigree showing Inheritance of Huntington’s disease
? Explain how you made your conclusion using evidence from the pedigree and the principles of genetics.

According to the pedigree above this would be a recessive trait. The reason this is a recessive trait is because no family member at the beginning of the pedigree was affected. Also no family members in the third generation of the pedigree were affected as well. If this were a dominant trait I see it affecting more family members in the earlier stages of the pedigree.

2. What would a Punnett square that shows how the son in generation IV (marked with an A) inherited cystic fibrosis look like? | A| a|
A| AA| Aa|
a| Aa| aa|

Key:
Male with Huntington’s disease
unaffected male
Female with Huntington’s disease
unaffected female
Generation
I
II
III
IV
V
Pedigree showing inheritance of Huntington’s disease
Key:
Male with Huntington’s disease
unaffected male
Female with Huntington’s disease
unaffected female
Generation
I
II
III
IV
V
Pedigree showing inheritance of Huntington’s disease
B
B

Questions:

1. According to the pedigree, is Huntington’s disease inherited as a dominant or as a recessive traitKey: male with Huntington’s Disease
unaffected male
female with Huntington’s Disease
unaffected female
Generation
I
II
III
IV
V
Pedigree showing Inheritance of Huntington’s Disease
Key:
male with Huntington’s Disease
unaffected male
female with Huntington’s Disease
unaffected female
Generation
I
II
III
IV
V
Pedigree showing Inheritance of Huntington’s Disease
? Explain how you made your conclusion using evidence from the pedigree and the principles of genetics.

This obviously a dominant trait, the reason I say this is because every generation is affected by the disease. This shows a dominant pattern in genetics affecting every generation. Also if you notice most affected are the males in the pedigree, which are known to be the dominant gene.

2. What would a Punnett square that shows how the first daughter in generation II (marked with a B) did not inherit Huntington’s disease look like? | B| b|
b| Bb| bb|
b| Bb| bb|

3. What is the role of chromosomes in the inheritance of genetic traits, such as cystic fibrosis and Huntington’s disease?

“Genetics, the study of biologic inheritance, explains how and why certain traits, such as hair color and blood types, run in families. Each individual develops from a single fertilized egg, which contains all the information necessary for the development of innate mental and physical characteristics. This information is carried in twenty-three pairs of rod-shaped chromosomes (containing thousands of genes) that are responsible for determining and transmitting hereditary characteristics. Each pair of chromosomes includes one inherited from the mother and one from the father”....
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