Genetics

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Associate Program Material

Genetics Worksheet

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

Questions:

1. According to the pedigree, is cystic fibrosis inherited as a dominant or as a recessive trait? Explain how you made your conclusion using evidence from the pedigree and the principles of genetics.

-Cystic fibrosis is inherited as a recessive trait. Each child of 2 carriers has a ¼ chance of inheriting 2 recessive alleles. A person with 2copies of this allele has 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?

| |A |a |
|A |AA |Aa |
|a |Aa |aa |

Questions:

1. According to the pedigree, is Huntington’s disease inherited as a dominant or as a recessive trait? Explain how you made your conclusion using evidence from the pedigree and the principles of genetics.

-Huntington’s disease is inherited as a dominant gene. Any child born to a parent with the allele has a 50% chance of inheriting the allele and the disorder. The allele that causes Huntington’s disease is dominant but lethal when inherited in 2 copies.

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?

-Chromosomes carry the genetic traits.
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Key:
[pic] male affected with cystic fibrosis
[pic] unaffected male
[pic]...
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