What Is the Probability of Their Child Having Sickle Cell Anemia?

[User Name]

Among black Americans, the frequency of sickle cell anemia is about .0025. What is the frequency of heterozygotes? When one black American marries another, what is the probability that both will be heterozygotes? If both are heterozygotes, what is the probability that one of their children will have sickle cell anemia?


I've already solved the first two questions, and now I'm just focusing on the last question. My question is, would the probability of one of their children having sickle cell anemia be the original .0025 that was given to me? Or would it be .25 (the probability of two recessive alleles when you cross two heterozygotes)?

Thanks, in advance. =]

 

[Moonbear]

For the last question, you're switching from population genetics to an individual cross. I suspect that's the reason for including that question, to remind you to think about whether you're working at the population level or individual level. That should tell you which of your answers to use.

 

[jumbogala]

Think of this question as three separate questions. Could your teacher still ask you the last question if you did not have the first two (assuming you still know you are working with sickle cell anemia)?

Yes, you could.

So now using ONLY the information in the 3rd question, can you figure out the answer?