Question

The BRCA1 protein is coded for at position 5677 on chromosome 17. Mutations in the BRCA1 gene are associated with elevated risk of breast cancer. BCPR is another gene on chromosome 17. BCPR codes for tp53, a tumor-suppressor protein. When functioning properly, tp53 reduces the chances of tumor growth for multiple cancers, including breast cancer.

For simplicity, we will call healthy BRCA1 alleles 1+ and malfunctioning BRCA1 alleles 1-. We will call healthy BCPR alleles 2+ and malfunctioning BCPR alleles 2-.

Alyssa and Vikas have a child named Connor. Connor is a carrier for the BRCA1 malfunctioning allele, giving him a BRCA1 genotype of 1+1-. He is also a carrier for the BCPR malfunctioning allele, giving him a BCPR genotype of 2+2-. (10 points)

Alyssa is heterozygous for the malfunctioning BRCA1 allele while Vikas is homozygous for the healthy BRCA1 allele. Alyssa is homozygous for the healthy BCPR allele while Vikas is heterozygous for the malfunctioning BCPR allele.

4. Without crossing over, what are the possible allele combinations of Connor’s gametes? What are the possible combinations with crossing over? Drawings are not required in your answer, but they may help you. (4 points)

5. Connor’s wife, Kim, is homozygous for the BRCA1 malfunctioning allele. Kim’s father is heterozygous for the BRCA1 alleles, while her mother is homozygous for the healthy BRCA1 allele. Where did a mutation likely occur, before Kim was born? (2 points)

Answer 1

Vikas it it (1+ 2t 1-2t occurred in the egg of Kim's mother. Alyssa 1+1 2+2+ 2+2- Gametes 1+ 2t 1+2 4. Combinations itit 2+2+ itotatz it 12+2+ ti 2+2 I Conna Kim's Father Kim's Mother it it it 1 Gametes tit Without mutation, there is no possibility for homozygous malfunctioning BRCA1 genotype. Mutation (1 + (it