Can't see the question because it requires a login username and password which I'm assuming only you can access. Sorry, can't help there... maybe get a screenshot of the question?
Can't see the question because it requires a login username and password which I'm assuming only you can access. Sorry, can't help there... maybe get a screenshot of the question?
Any female that produces a haemophiliac son must be heterozygous (ask me if you don't understand why this is). For the females that have not reproduced, it's not possible to say whether they are heterozygous or not. Even for II-1, it's not possible to say whether she is heterozygous or not because she would only produce haemophilac sons with a probability of 50% (ask me if you don't know why this is).
Yeah, so I'm unless I'm missing a trick, the question is badly worded, because one can only say definitively that a female is heterozygous but not that she is not heterozygous. Also, the question is badly worded in another sense that one cannot technically be heterozygous for haemophilia, but only for the actual allele that causes it (i.e. people are heterozygous for alleles, not traits).
Any female that produces a haemophiliac son must be heterozygous (ask me if you don't understand why this is). For the females that have not reproduced, it's not possible to say whether they are heterozygous or not. Even for II-1, it's not possible to say whether she is heterozygous or not because she would only produce haemophilac sons with a probability of 50% (ask me if you don't know why this is).
Yeah, so I'm unless I'm missing a trick, the question is badly worded, because one can only say definitively that a female is heterozygous but not that she is not heterozygous. Also, the question is badly worded in another sense that one cannot technically be heterozygous for haemophilia, but only for the actual allele that causes it (i.e. people are heterozygous for alleles, not traits).
As far as I'm aware, your teacher just wants you to identify the mothers producing haemophiliac sons, but they haven't worded the question properly. There's no way that you could possibly determine whether a woman is heterozygous or not in the pedigree if she hasn't reproduced. So that's it really, you should be able to move onto the next question.
Any female that produces a haemophiliac son must be heterozygous (ask me if you don't understand why this is). For the females that have not reproduced, it's not possible to say whether they are heterozygous or not. Even for II-1, it's not possible to say whether she is heterozygous or not because she would only produce haemophilac sons with a probability of 50% (ask me if you don't know why this is).
Yeah, so I'm unless I'm missing a trick, the question is badly worded, because one can only say definitively that a female is heterozygous but not that she is not heterozygous. Also, the question is badly worded in another sense that one cannot technically be heterozygous for haemophilia, but only for the actual allele that causes it (i.e. people are heterozygous for alleles, not traits).
to be heterozygous either their father must have haemophilia or the mother must be a carrier, that's all I've worked out so far
to be heterozygous either their father must have haemophilia or the mother must be a carrier, that's all I've worked out so far
Okay, let's do it this way:
1)The only haemophiliacs in the pedigree are male.
2)Males are XY. Therefore, they must have gotten a mutant allele from their mother.
3)No females in the pedigree are haemophiliacs. Therefore, every female that produces a hameophiliac son must be heterozygous for the mutant allele.
See?
If you look at the pedigree, you should find that every female that has had children in the pedigree has produced haemophiliacs, and therefore must be heterozygous. The only exception if II-1; so for II-1 it's not possible to say whether she is heterozygous or not.
These conditions only affect men. It is extremely rare to see a women affected (they would need to have fathers who had the condition and mothers who were carriers and even then it would only be a 50% chance of being affected).
Man unaffected X Y
Man affected XY
Female carrier X X ("heterozygous")
Female unaffected X X ("homozygous")
In the question female carrier is called "heterozygous" since they have one normal and one abnormal X.
All X-linked recessive conditions follow a common inheritance pattern.
Normal male X Y + Carrier Female X X
Offspring:
1/4 - Normal male X Y 1/4 - Normal female X X 1/4 - Female carrier X X 1/4 - Haemophilia male X Y
This is the royal family showing haemophilic men and female carriers.
As you can see all the children affected have mothers who are carriers and you see this will all recessive X linked conditions.
Again, that image is problematic because they wouldn't be able to say whether Helena and Louise where carriers or not without genotyping (technology wasn't available in those days). One cannot also say with certainty that Victoria (who married Frederick) wasn't a carrier.
1)The only haemophiliacs in the pedigree are male.
2)Males are XY. Therefore, they must have gotten a mutant allele from their mother.
3)No females in the pedigree are haemophiliacs. Therefore, every female that produces a hameophiliac son must be heterozygous for the mutant allele.
See?
If you look at the pedigree, you should find that every female that has had children in the pedigree has produced haemophiliacs, and therefore must be heterozygous. The only exception if II-1; so for II-1 it's not possible to say whether she is heterozygous or not.
These conditions only affect men. It is extremely rare to see a women affected (they would need to have fathers who had the condition and mothers who were carriers and even then it would only be a 50% chance of being affected).
Man unaffected X Y
Man affected XY
Female carrier X X ("heterozygous")
Female unaffected X X ("homozygous")
In the question female carrier is called "heterozygous" since they have one normal and one abnormal X.
All X-linked recessive conditions follow a common inheritance pattern.
Normal male X Y + Carrier Female X X
Offspring:
1/4 - Normal male X Y 1/4 - Normal female X X 1/4 - Female carrier X X 1/4 - Haemophilia male X Y
This is the royal family showing haemophilic men and female carriers.
As you can see all the children affected have mothers who are carriers and you see this will all recessive X linked conditions.
Again, that image is problematic because they wouldn't be able to say whether Helena and Louise where carriers or not without genotyping (technology wasn't available in those days). One cannot also say with certainty that Victoria (who married Frederick) wasn't a carrier.
For question 3, I basically drew a punnet square and said that the females have a 1 in 2 chance of being heterozygous, is there more I can say about this or is that enough?
For question 3, I basically drew a punnet square and said that the females have a 1 in 2 chance of being heterozygous, is there more I can say about this or is that enough?
Yeah, 50% is right. That should almost definitely be enough, as you've given the answer and shown how you got to it. There's nothing else to add, really..