hi!
say P dominant p recessive
the answer is option 2)
if recessive the second generation: pp X pp
offspring 100% pp, we can’t have a healthy carrier
do we actually have to analyze each and every pedigree or is there any shorter method as well?
it’ll take about 2/3 mins for these kind of questions
Just look at the patterns mostly if both parents have the disease, all children should be affected, if only sons are affected by a carrier mother - it’s X linked. If it’s recessive, it could skip generations, etc.
Why can’t option 1 be the answer if both the parents are homozygous dominant?
Hi
because the question is asking which one CAN’T work with autosomal recessive
in 1) auto dominant works i agree
but auto recessive works too
parent pp X pp
all offspring are pp
Wait, but if both parents have the disease, how does autosomal recessive work?
are you asking how they can pass the gene to their offspring?
not all recessive traits are lethal
for example blue eyes are a recessive trait
two parents homozygous for the blue eyed genes will only have blue eyed children
No no no. I meant to ask that if we consider the first option = both parents are homozygous for the dominant allele which can be passed to generations and autosomnal dominance works there.
But if both parents have the disease (i.e. are affected) how does autosomal recessive work?
in this question we are working with hypothetical scenarios
for 1) both parents auto dominant PP X PP so offspring 100% PP is a possibility
we can also consider the possibility that the parents are pp X pp so offspring 100% pp
the two options are hypothetical and can be analysed independently from one another
this is like one of Ari’s “is it real” questions
if both parents have the disease and we suppose it’s recessive, they would be pp and pp
their children are all pp so are affected by the disease
it’s a possibility that would explain the diagram in 1)
i hope i am understanding your question?