00:01
Galactosemia is autosomal recessive.
00:03
A normal couple has a child with galactosemia.
00:07
So the child, let's say, is a -a, so too recessive because they have the trait.
00:14
So the parents, we know they don't have the trait, so they each have a dominant allele, but they also have a recessive because they had a child with galactosemia.
00:24
So we know, going into this, that the parents are both heterozygotes.
00:28
Now, what is the chance of the next three children will be galactosemic? so, first of all, what's the chance of a child being galaxosemic? well, this is a mono -hybrid cross.
00:42
So if you want to do a punnet square, you'll find that there's this ratio of genotypes, like so...