If parents are normal and have 4 children inwhich 2 are normal but 2 children are infected. What kind of genotype does the parents have, i mean how is it that normal parents have infected children "/ ?

infected???

 

Usually infections aren't spread through the genome.. I suppose viruses could be in special cases.

 

Though, I think you are just wording your question incorrectly. Figure out what you mean by "infected" and get back to us.

by infected i meant things like diabetic or some kind of genetic disorder such as cystic fibrosis

Image two alleles (versions of a gene). One gives the disease, we'll call it "a", and one is normal, we'll call it "A". Very often, a disease will be recessive, meaning you have to get 2 copies of "a" to get it.

 

So, if both parents carry only one copy (genotype Aa);

 

There's a 50% chance for their children to be also carriers; Aa

25% change of getting the 2 normal alleles; AA

25% change of getting the disease; aa

i thought that the diseases were the dominant ones?

i thought that the diseases were the dominant ones?

It depends on the disease. You can't make a blanket statement like that.

 

If diseases were always dominant, it would probably be an allele that gets eliminated from the population very quickly. But, then, there are exceptions to every "rule."

If they were dominants, then the parents would have had the disease.

yea sorry, i just started learning this in bio class, need some info to learn more about genotypes and Mendel's experiments.

 

EDIT: so it is possible that the parents do not have the disease, but their children will get it? like a recessive recessive?

so it is possible that the parents do not have the disease, but their children will get it? like a recessive recessive?

IIRC something like that would be possible if the genotype of parents is heterozygote. Suppose that a certain disease is shown up only with to recessive alleles (aa) . So if the parents are both Aa after combining them we'd get

 

(p) Aa Aa

(f) AA Aa aA aa

 

 

but remember that this is only the dominant-recessive type

Yeah, i just had a lesson on that..haha reading ahead isn't in my genes(or rather, chromosomes/DNA)