how much do we have to know about genetics pedigrees?

[mrh125]

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is it just the "this is an autosomal dominant pedigree, this is x-linked recessive etc" (that stuff's not bad) or would we be expected to actually do pedigrees and find out the genotypes of everything on there? if it's the later, i've always had a little trouble figuring out to do those out, so if you had any tips that'd be great.

are these basic summaries of the trends right?
autosomal dominant - appears every generation even sex ratio
autosomal recessive - can skip generations, even sex ratio
x-linked recessive - affects males more frequently than females
x-linked dominant - affects both sexes indiscriminately since it's dominant.

 

[phantomcello]

Correct your x-linked recessive to read - affects males more frequently than FEMALES.
This is a good general guideline for answering pedigree questions but you need to understand why these trend occur i.e. how the genotype affects the pedigree and in turn the phenotype of the individual on the tree. I'm not sure what you mean by "do a pedigree" but finding genotypes on a pedigree is likely -- otherwise the pedigree would be pointless. You might be asked to determine a particular genotype of a certain individual when two people on the pedigree mate. You would need to know the probability of the gene being passed on to a particular offspring and the genotypes of the parents.

 

[mcloaf]

I'd consider pedigree analysis a skill you'd probably want to be comfortable with for the MCAT.

 

[dyspareunia]

is it just the "this is an autosomal dominant pedigree, this is x-linked recessive etc" (that stuff's not bad) or would we be expected to actually do pedigrees and find out the genotypes of everything on there? if it's the later, i've always had a little trouble figuring out to do those out, so if you had any tips that'd be great.

are these basic summaries of the trends right?
autosomal dominant - appears every generation even sex ratio
autosomal recessive - can skip generations, even sex ratio
x-linked recessive - affects males more frequently than females
x-linked dominant - affects both sexes indiscriminately since it's dominant.

Probably better to think of it as ways to rule things out. For example, every generation plus male-to-male transmission = autosomal dominant. There is no male-to-male transmission (this is important to know) in x-linked diseases.