What can you conclude about the risk (with each pregnancy) that a couple could have a child affected with an autosomal dominant disorder if...
One parent is affected (heterozygous) and the other parent is unaffected.
I did a punnet square and concluded it was 50 percent because half were Aa and half were aa.
But a classmate told me to line up Aa and aa and conclude that there is only a 25 percent chance that a child is affected because there is only one capital or dominant A and three are "a". Which do I do?