genetic, reasoning?

Question

a study is undertaken to determine the nature of a mutant allele of the "G gene" Many families in which both parents have the genotyepe Gg are found, and their children are genotyped. the researchers found 65 children with a Gg genotype, 35 children with GG genotype, and 0 children with gg genotype
how can you explain this abnormal ratio?

Answer 1

My hypothesis would be that the gg genotype is lethal.

In a Gg x Gg cross the expected ratios would be:

25 GG (1/4)
50 Gg (1/2)
25 gg (1/4)

but the actual result was:

35 GG (1/3)
65 Gg (2/3)

If you look carefully, the actual results represent the expected results if all double recessives were removed.

Answer 2

I agree with floundering penguins and had the same thought before I saw his answer. What you have is a gene which is lethal, likely causes spontaneous abortions or never implants or never gets past the initial first few cells to develope in almost all cases. The actual sample size here would be more like 130 if all the fertil;ized eggs had survived, therefor the normal expected distribution based on 50% and 25% would be 65 Gg and about 32GG and 32 gg (all of which were never born). These numbers are within the statistical variation expected in such a small sample.

Answer 3

Of course, nothing is that simple. How a trait physically shows up in you (your phenotype) is a result of your genotype. And your genotype is composed of all the different alleles you inherited from both parents.

Answer 4

gg is lethal, meaning that the G gene, when occuring in a homozygote recessive allele, does not allow the children to live.

Answer 5

Interesting. Where was this study published? I'd like to read it for myself.