Question

women can inherit alleles of a gene called brca1 that puts them at higher risk for breast cancer. the alleles associated with elevated cancer risk are dominant. of the genotypes listed below, which carries the lowest genetic risk of developing breast cancer?
○ all of these genotypes carry equal risk.
○ bb
○ bb and bb
○ bb
○ bb

Explanation:

Step1: Analyze dominant and recessive alleles

Let \( B \) represent the allele for elevated cancer risk (dominant) and \( b \) represent the allele for no elevated risk (recessive).

Step2: Analyze each genotype

• For \( BB \): Both alleles are dominant. So, there is a high genetic risk.
• For \( Bb \): One dominant allele (\( B \)) is present. So, there is an elevated genetic risk.
• For \( bb \): Both alleles are recessive. Recessive alleles are only expressed when in the homozygous state. Since the allele for elevated risk (\( B \)) is dominant and not present here, this genotype carries the lowest genetic risk.

Answer:

bb