(Solved) How to determine a monohybrid cross genotype

aerodude30

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11 years ago

How to determine a monohybrid cross genotype

I have a question here it says
"In humans having freckles (F) are dominant over not having freckles (f). George has freckles just like his father. However, georges mother does not have freckles. Wha is georges genotype as it pertains to this particular trait?"

i think george has a 75% chance of getting freckles but im not sure can anyone help answer this question?

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bio_man

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11 years ago

His mother has to be ff.

Father can be either FF or Ff.

Therefore, George must be either Ff of FF.

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Doctor-2-B

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bio_man

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11 years ago

Sorry, you're absolutely right. Where's my head at these days...

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Doctor-2-B

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11 years ago

It's all gravy. We're all here to help. Slight Smile

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Pretty fly for a SciGuy

aerodude30 Author

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11 years ago

Quote from: Doctor-2-B (11 years ago)

Since freckles are a dominant trait, we know that the mother must be recessive homozygous (ff) since she doesn't have any (FF or Ff would make her have freckles). Since his father has freckles, he's either FF or Ff. Since George has freckles, he's either FF or Ff, but since his mother is ff, he HAS to be Ff since she can't give him an F.

Answer is Ff.

As an aside, since we don't know whether his father is FF or Ff, future progeny actually have a 50% chance of having freckles (unless one of his siblings doesn't have freckles, then we would know that his father is Ff, then the ratio would be 75% freckles, and 25% no freckles because we would know for sure that his father is Ff).

Post Merge: 11 years ago

@bio_man:
George can't be FF because we know his mother is ff. He can only be Ff (because he has the freckles phenotype and his mother is genotypically ff).

Ahhh thank you very much that makes sense and that will help with some of my other problems!

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Doctor-2-B

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11 years ago

Sure, of course. That's what we're here for.

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Pretty fly for a SciGuy

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