Question

Enzyme A is required to produce red pigment on the abdomen of a bird. A biochemist evaluated birds with red and pale (not red) abdomens and determined that a minimum of 50 units of Enzyme A is necessary to obtain red pigmentation. A new mutation in the gene that produces Enzyme A, results in only 10 units of Enzyme A in birds homozygous for the mutation. The mutation would be best considered as"

A: suppressor

B: null

C: co-dominant

D: gain of function

E: leaky

Answer 1

Here from the above information the mutation cuses a decrease in the prodduction of the Enzyme A (from 50 unit to 10 unit) so the function of the Enzyme A reduced due to the mutation.

• supressor mutation restores the original phenotypic character.So it is difficult to say whethwe if it is a supressor mutation as the previous phenotypic character of the Enzyme A is unknown.
• Null mutation encodes specific enzyme leads to the non function of a specific enzyme.But here the enzyme is functioning in less quanata. So it can not be Null mutation.
• co dominant mutation involves more than one phenotypic character. so according to the information it is not a co dominant mutation.
• Gain of function mutation causes enhancement of a protein. But here the function of the Enzyme producing gene is decreased. So it can not be gain of function.
• Leaky mutation cuses partially impairment of a certain phenotypic characteristic.

According to that this mutation is definately a Leaky mutation.