Pedigree
Moderators: honeev, Leonid, amiradm, BioTeam

 Garter
 Posts: 3
 Joined: Thu Oct 18, 2007 1:05 am
 Location: Canada
Pedigree
#1 is to determine what type of inheritance is involved.
My ans: autosomal recessive
#2 is to write the genotype for each individual using A for normal pigmentation and a for albinism and if genotype is unknown, A_
This is where I'm having a bit of difficulty.
My ans:
Gen I: Aa Aa AA aa
Gen II: A_ Aa aa Aa Aa Aa AA
Gen III: A_ A_ aa A_ A_
#3 is to determine the probability that the marriage between individuals III1 and III5 will produce albino children.
I'm not sure about this either.
My methodology would be to first find the probability that these individuals are carriers and then the probability that they would produce albino children. I would use a punnett square to find out the probability that they are carriers but if I don't know the genotypes (considering I am right in #2), how do I do this?
Thanks
My ans: autosomal recessive
#2 is to write the genotype for each individual using A for normal pigmentation and a for albinism and if genotype is unknown, A_
This is where I'm having a bit of difficulty.
My ans:
Gen I: Aa Aa AA aa
Gen II: A_ Aa aa Aa Aa Aa AA
Gen III: A_ A_ aa A_ A_
#3 is to determine the probability that the marriage between individuals III1 and III5 will produce albino children.
I'm not sure about this either.
My methodology would be to first find the probability that these individuals are carriers and then the probability that they would produce albino children. I would use a punnett square to find out the probability that they are carriers but if I don't know the genotypes (considering I am right in #2), how do I do this?
Thanks
 Attachments

 pedigree.JPG
 (10.17 KiB) Downloaded 44 times
You cannot really know if II2 and II7 are Aa or AA and as a consequence there is no way to be 100% sure of III1, III4 and III5's genotypes.
The method is correct and you have only 2 choices: either you research the probability to be a healthy carrier of the albinos gene in the general population and use it to calculate the probability of carriage of albinism for those individuals. Or you assume that it is to small to be relevant, and just assume that they are AA. Note that II2 has only 50% of being Aa
The method is correct and you have only 2 choices: either you research the probability to be a healthy carrier of the albinos gene in the general population and use it to calculate the probability of carriage of albinism for those individuals. Or you assume that it is to small to be relevant, and just assume that they are AA. Note that II2 has only 50% of being Aa
Patrick
Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)
Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

 Garter
 Posts: 3
 Joined: Thu Oct 18, 2007 1:05 am
 Location: Canada
No! II1 and II7, the nonmembers of the family. because you cannot really know if they are aA or AA, but the probability to be acrrier is probably small enough to be neglected compared to the original family.
Patrick
Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)
Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

 Garter
 Posts: 3
 Joined: Thu Oct 18, 2007 1:05 am
 Location: Canada
Who is online
Users browsing this forum: No registered users and 6 guests