The probability that their baby will be a carrier of the gene for PKU is (A) __________. The probability that their baby will be affected by PKU is (B) __________. If both genotypes were Pp, the probability that their baby would be affected by PKU would be (C) _________.
my answer for first one is 3/4 third answer is 1/4 i cant figured the second answer.
I am not a biology expert, but here are some mathematical aspects of the problem.
If both parents are heterozygous (contains one PKU allele, or Pp), the outcomes are:
PP has PKU (probability 1/4)
Pp carrier
pP carrier
pp non-carrier (probability 1/4)
Probability of being a carrier is therefore (1/4+1/4)=1/2.
The probability of inheriting a PKU allele is 1 in 50 in the US general population.
Assuming random distribution, the probability of having both parents heterozygous is (1/50)*(1/50)=1/2500.
Out of these parents, there is a 1/4 probability that the child will have PKU, making a 1/10,000 probability in the general population.
The question is not clear if we assume that both parents are heterozygous or not. So you may have a better context for the correct answers.
To find the probability that a baby will be a carrier of the gene for PKU, we need to consider the genotypes of the parents.
Let's assume that PKU is a recessive trait and is represented by the genotype "pp". The genotype "Pp" represents a carrier and "PP" represents a non-carrier.
Now, let's denote the genotypes of the parents as follows:
Parent A: Pp
Parent B: Pp
To determine the probability that their baby will be a carrier of the gene for PKU, we need to consider the possible genotypes that can result from their combination.
When two individuals with the genotype "Pp" reproduce, the possible genotypes their offspring can have are: PP, Pp, Pp, and pp.
Out of these possibilities, only 1 out of 4 has the genotype "pp" which represents being affected by PKU. Therefore, the probability that their baby will be a carrier of the gene for PKU (A) is 3/4.
To find the probability that their baby will be affected by PKU (B), we need to specifically consider the genotype "pp" which represents being affected by PKU.
From the earlier analysis, we found that 1 out of 4 possible genotypes (pp) leads to the baby being affected by PKU. Hence, the probability that their baby will be affected by PKU (B) is 1/4.
Now, for the third part, if both genotypes were Pp, there would be no chance of the baby being affected by PKU (since the genotype "pp" is required for that). The genotype "Pp" only means that the baby is a carrier. Therefore, the probability that their baby would be affected by PKU (C) would be 0 out of 4 or simply 0.
To summarize:
(A) Probability of the baby being a carrier of the gene for PKU = 3/4
(B) Probability of the baby being affected by PKU = 1/4
(C) Probability of the baby being affected by PKU given both genotypes are Pp = 0