Genetics warmup for MCAT

[chandler742]

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I decided to throw a question in here for you to chew on.

Huntington's disease is an autosomal dominant disease. Homozygotes are LETHAL alleles before birth. On the other hand, heterozygotes live until mid 30's before developing the neurodegenerative conditions.

A father and mother heterozygous for Hh(huntington's disease) have one daughter. Restriction Fragment Length Polymorphism(RFLP) results of the family is as follows(i.e with restriction endonuclease BAM III). The elecrophoresis of the Father has two bands, mother has two bands, daughter has one band.

What can we say about the daughter?

A) She is homozygous dominant for huntington's disease
B) She is a Hh genotype i.e. heterozygous
C) She does not have a huntington's gene
D) Just give me the answer

Clue: Don't forget about the old Punnett Square!!

 

[Mr. Z]

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Well, we know she is not heterozygous, or else she would have two bands.

We also know she is alive, therefore she must not have the disease😱