Gene expression - tyrosinase

Hi there,

I just wanted to ask about this question from my level 2 Biology workbook.

"Two parents with normal colour skin and hair had six children, three were albino. As the children matured, one of them began growing brown hair on her eyebrows, hands, and lower legs. Studies have shown that the temperature activity range of the normal enzyme tyrosinase is between 30-45°C. However, the activity of the faulty tyrosinase taken from the girl decreased rapidly in temperatures higher than 33°C.

Discuss explanations for the distribution of colour in the hair on different areas of the albino girl’s body.

  • State genotypes of parents.
  • Suggest possible explanation why only one child developed colour.
  • Refer to other examples of environmental effects on gene expression."

So far, I’ve written that only one girl developed coloured hair perhaps because she moved to a region of colder climate (and not her albino siblings). These lower temperatures would’ve allowed to tyrosinase activity to be sufficient enough to produce melanin and in turn colour, especially on the extremities of her body where it tends to be colder. Does this sound reasonable?

I also said: “The genotypes of both parents for the tyrosinase gene must be heterozygous since the albino child had to receive two copies of the recessive allele, one from each parent, in order to express the autosomal recessive disorder.” And for the “refer to other examples”, I just wrote something about pH levels in soil on the expression of flower colour .

Thanks very much!

Hi NickC
Yes :smile: these points are the elements of a good answer. If you have given more detailed explanations instead of short statements like “in turn colour” it will be a great answer. Especially if you have added detail to make it completely clear eg name the extremities of the body that are colder.