Question

consider the following single - gene traits. which of the following individuals would have the specific condition listed? check all that apply.
check all that apply
□ an individual who is heterozygous for cystic fibrosis
□ an individual who is homozygous recessive for galactosemia
□ an individual who is homozygous dominant for phenylketonuria
□ an individual who is heterozygous for huntingtons disease
□ an individual who is heterozygous for juvenile retinoblastoma

Explanation:

1. Cystic fibrosis is autosomal recessive. Heterozygous individuals are carriers, not affected. So this is incorrect.
2. Galactosemia is autosomal recessive. Homozygous recessive individuals have the condition. Correct.
3. Phenylketonuria (PKU) is autosomal recessive. Homozygous dominant individuals have the normal phenotype (do not have PKU). Incorrect.
4. Huntington's disease is autosomal dominant. Heterozygous individuals (one dominant allele) have the disease. Correct.
5. Juvenile retinoblastoma can be autosomal dominant with incomplete penetrance, but heterozygous individuals (with the dominant allele) can have the condition. Correct.

Answer:

• An individual who is homozygous recessive for galactosemia
• An individual who is heterozygous for Huntington's disease
• An individual who is heterozygous for juvenile retinoblastoma