12) A man without hemophilia and a woman with hemophilia are expecting their fir
ID: 71251 • Letter: 1
Question
12) A man without hemophilia and a woman with hemophilia are expecting their first child. Show the Punnet square for this cross.
a. What are the odds that their child will be a daughter with hemophilia?
b. If they have a son, what is the probability that he will have hemophilia?
c. If they have a daughter, what is the probability that she wull be a carrier?
13. Suppose you have two rose plants, both with pink flowers. You cross the two plants and are surprised to see that while most offspring have pink flowers, some have red flowers and some have white flowers.
a. What is the mode of inheritance for this trait?
b. What cross should you perform to get all pink-flowered roses?
14. List the 3 temperature stages of a single PCR cycle and describe what occurs during each stage.
15. What is a primer and what role does it play in PCR?
16. A DNA sample has 2 copies of a gene. How many copies of that gene would be present after conducting PCR of that gene for 20 cycles?
Explanation / Answer
12). Haemophilia is a sex linked disease, in case of sex linked diseases females have to carry two defective alleles to become affected and presence of only one defective allele causes males to be affected.
Cross between an affected mother and unaffected father will have the offspring with the following genotypes (XH represents the defective allele).
XHXH* XY = XHX, XHY, XHX, XHY
Means all the males ate affected and all the females are carrier.
a. The odds that their child will be a daughter with hemophilia -----> 1/2*0 = 0
b. If they have a son, the probability that he will have hemophilia ---------> probability of being affected= 100% (all male inherit ine X chromosome from their mother, who is affected).
c. If they have a daughter, the probability that she will be a carrier --------> probability of being a carrier = 100% (all female inherit ine X chromosome from their mother, who is affected).
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