Genetics 2

Question 1

What is a pedigree?

Answer 1

It is a diagram of a family tree, of affected and unaffected individuals.

Question 2

What is the testcross used for?

Answer 2

It is to determine the unknown genotype of the person with a dominant phenotype. Basically you have to find out whether the individual is homozygous dominant or heterozygous for the trait.

Question 3

Tips for autosomal recessive pedigrees:

Answer 3

• homozygous recessive individual are affected
• heterozygous are carriers
• homozygous dominant is not affected
• normal parents can have affected offspring
• the condition can often appear suddenly or skip a generation

Question 4

Tips for autosomal dominant pedigree:

Answer 4

• homozygous recessive individuals are not affected
• homozygous dominant and heterozygous is affected
• affected offspring have at least one affected parent
• the condition does not skip a generation