Associate Program Material

Genetics Worksheet

Review the images below and answer the follow-up questions.

Key: male affected with cystic fibrosis unaffected male female affected with cystic fibrosis unaffected female
Generation

I
II
III
IV

a a a
A
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

a a a
A
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, the disease, cystic fibrosis is an inherited recessive trait. Each parent can be the carrier of the diseased allele and not have developed the disease themselves, but they do pass it on to the next generation. Any individual having two duplicates of this allele will develop cystic fibrosis. This means that having both parents as carriers the second offspring has about 1/4 of a chance of inheriting the two recessive alleles, thus developing cystic fibrosis. 2. What would a Punnett square that shows how the son in generation IV (marked with an A) inherited cystic fibrosis look like? The son is homozygous recessive and also the disease is an inherited recessive allele. He developed the