Genetics Help 9th Grade?
Question by «g¥π姆«: genetics help 9th grade?
a husband and wife are heterozygous for cystic fibrosis. their son has cystic fibrosis. their second child, a daughter, does not. draw a pedigree.
so i’m just confused. so the parents are both heterozygous? or just one? and cystic fibrosis is recessive or dominant? so does that mean that the parents are both carriers, the son has it, and the daughter is normal?
The top answer:
Answer by Laurier
first of all Cystic Fibrosis is recessive, you can figure that out through the internet.
Now onto what the genes would look like
lets make Y = normal gene y = cystic fibrosis gene
since the parents are both heterozygous (since it said a husband AND wife ARE heterozygous) for the gene their genes would both be: “Yy”
The son has Cystic Fibrosis so his gene would be: yy
and the daughter doesnt have it so hers would be: YY
now you just have to draw a pedigree for that
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the above is right just don’t use Yy (X and y are sex chromosomes) use Aa or Bb
Yes. Both are heterozygous.
C=no cystic fibrosis c=gene for cystic fibrosis.
………………MOTHER
……… _____C________c_____
F…….|……………..|……………..|
A..C..|……CC…….|……Cc…….|
T…….|__________|_________ |
H……|………………|……………..|
E..c..|…….Cc…….|……cc……..|
R……|__________|__________|
Neither a homozygous dominant (CC) and a heterozygous (Cc) have cystic fibrosis. Their ‘good’ C gene compensates for and bad ‘c’ gene they might have. The daughter could either be Cc or CC.
The son can only be cc (homozygous recessive), Otherwise, he would not have cystic fibrosis.
From these parents, there is a 25% chance of having a child with Cystic fibrosis. (Taken from the punnet square).
any genetic disorder that can have carriers is recessive. that means that the cystic fibrosis allele can be represented as “c”, therefore that normal allele would be dominant “C”
homozygous dominant would be CC which would mean normal
heterozygous would be Cc which would be a carrier
homozygous recessive would be cc which would mean that they have cystic fibrosis
since that parents are heterozygous, they are both Cc. which means that their gametes would either contain C or c
the possible combinations for both parents are… CC, Cc,Cc, and cc the child is most likely to be a carrier but has a 25% chance at being normal and 25% chance of having cystic fibrosis.