Genetics Worksheet

Genetic Worksheet

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 a recessive trait. If you have one CF gene and one non-CF gene, you will be a carrier but not have CF. I referred back to Mendel mentioning that the trait may not show up in somebody but it can still be passed on to the next generation. He also states that the inheritance of each trait is determined by genes that are passed on unchanged. So as the CF gene is not present, it becomes present depending on the ratio of genes as it passes down.

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]

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.

According to the pedigree, I believe this would be a recessive trait. The reason why is I say this is because no family member at the beginning of the pedigree was affected. Also there was no family members in the third generation of the pedigree were affected as well. If this were a dominant trait it could affect more family members in the earlier stages of the pedigree.

What is the role of chromosome in the inheritance of genetic trait and Huntington’s disease?

The chromosome carry the genetic traits. In a normal cell, each of these chromosomes had two parts, the chromatids. A reproductive cell, which is created in a process called meiosis, usually contain only one of the chromatids of each chromosomes.

Campbell Essential biology with physiology, 3rd Ed. Eric J. Simon, Jane B. Reece, andJean L. Dickey 2010.