Cystic fibrosis is inherited from parents only if both have the abnormal CF gene. Children of two parents with the CF gene will either be affected with the disease, a carrier but not affected or not have the gene.

Question

-Write an expression for the genitec makeup of children of two parents that are carriers or cystic fibrosis.
-What is the probability that a child will not be affected and not be a carrier?

Answer 1

This looks more like genetics than algebra.

Let N = normal gene and c = cystic fibrosis gene.

Assuming that both parents are carriers — they carry the gene but do not have CF — both of their genotypes would be Nc.

Use a Punnett square to determine probabilities.

http://en.wikipedia.org/wiki/Punnett_square

I hope this helps. Thanks for asking.