Answer:
To answer this question, we need to interpret the symbols and pedigree chart provided in Figure 6.
Explanation:
Here's a step-by-step approach to determine the genotype of female Z:
1. Understand the symbols:
- Squares represent males
- Circles represent females
- Filled symbols (black square or circle) indicate individuals with the recessive condition (homozygous recessive)
- Empty symbols indicate individuals without the condition (homozygous dominant or heterozygous)
2. Identify female Z:
Female Z is represented by the solid black circle, indicating that she is homozygous recessive for the trait in question, which in this case is haemochromatosis.
3. Determine the genotype of female Z:
Haemochromatosis is stated to be an inherited condition that occurs when a person inherits two copies of a recessive allele.
If we represent the recessive allele as 'r' and the dominant allele as 'R', then the genotype of female Z, who is homozygous recessive, is 'rr'.
Therefore, the genotype of female Z is 'rr'.
To explain this further, since female Z has the condition (indicated by the solid black circle), and haemochromatosis is a recessive condition, she must have inherited two copies of the recessive allele, one from each parent. This means that both her parents must have at least one copy of the recessive allele (either heterozygous or homozygous recessive).
