Human Pedigree Charts and Genetic Disease

Question 1

What are pedigree charts?

Answer 1

A means of evaluating the transmission of disease across several generations

Question 2

Why are consanguineous matings bad for genetics? What is more likely to happen in consanguineous matings?

Answer 2

Consanguineous mating is incestuous mating; bad because recessive alleles in the family gene pool are more likely to encounter each other- therefore genetic disorders are more likely to occur

Question 3

What are Barr bodies? When do they form and what role do they play in gene expression in females?

Answer 3

Barr body- an X chromosome that inactivates and condenses down
If a female is heterozygous for a particular X-linked gene, she will be a mosaic for that trait

Question 4

What is incomplete dominance and why does it occur? Give an example.

Answer 4

Genetic case where the dominant allele does not completely mask the recessive phenotype resulting in mixing of the dominant and recessive traits when both alleles are present

ex –> red flowers x white flowers = pink flowers; manx cats

Question 5

What is codominance and why does it occur? Give an example.

Answer 5

Genetic case where multiple alleles are dominant and their traits are both present when both alleles are present (heterozygotes)

ex –> erminette chickens; roan cattle