(Solved) A genetics probability question involving conditional probability

papitoahlstrom

wrote...

Go to Answer

Posts: 11

Rep:

9 years ago

A genetics probability question involving conditional probability

if a man with polydactyly syndrome and his normal wife plan to
have five kids, they want to know:

(1) what is the probability that only two of five kids will be
polydactylism?
(2) What is the probability that at least two of five kids will be
polydactylism

as known: (a) the husband’s mom is normal and (b) polydactylism
is caused by autosomal dominant mutation in a single gene

This is what I have so far

1. (5! x (0.5)^2 x (0.5)^2)/(2! x 3!) = 31%

2. I'm not really sure, but since the man must be dominant and the mom was normal, I'm assuming the man's genotype is Pp (polydactyl syndrome). The wife is normal so she must be pp. This means the genotypes of the offspring are 50% Pp and 50% pp. So for AT LEAST 2 kids to have polydactyl syndrome (Pp), that means the probability must be over 50%, right?

Read 1951 times

9 Replies

Report

Replies

bio_man

wrote...

Educator

9 years ago

Quote from: papitoahlstrom (9 years ago)

if a man with polydactyly syndrome and his normal wife plan to
have five kids, they want to know:

Help me out here, is polydactyly homozygous dominant, recessive, etc? Need this information to draw a pedigree.

Report

papitoahlstrom Author

wrote...

9 years ago

Quote from: bio_man (9 years ago)

Quote from: papitoahlstrom (9 years ago)

if a man with polydactyly syndrome and his normal wife plan to
have five kids, they want to know:

Help me out here, is polydactyly homozygous dominant, recessive, etc? Need this information to draw a pedigree.

The only information the problems gives is what I posted. A google search has led me to believe that it is a rare dominant trait. Hopefully that helps

Report

bio_man

wrote...

Educator

9 years ago

I'm stumped... View my attachment

Attached file

Thumbnail(s):

You must login or register to gain access to this attachment.

Report

papitoahlstrom Author

wrote...

9 years ago

Quote from: bio_man (9 years ago)

I'm stumped... View my attachment

I'm pretty sure it's Dd because not all 5 of the kids will have polydactyl syndrome. I think this question testing the statistical side more. Let's say that it is Dd. Do you know how to do the math so that we can predict ONLY two of the 5 kids will have it?
And to also predict that AT LEAST 2 have it?

Thank you for all your help so far. I appreciate it.

Report

rsb

wrote...

9 years ago

Try my solution, building on what bioman said in the sense that it's a 50% chance each time

Attached file

Thumbnail(s):

You must login or register to gain access to this attachment.

Report

papitoahlstrom Author

wrote...

9 years ago

Quote from: rsb (9 years ago)

Try my solution, building on what bioman said in the sense that it's a 50% chance each time

Yeah, that's what I got for my answer in my OP for question #1. #2 is the one I'm having a tough time with haha thanks!

Report

Answer accepted by topic starter

alexaDS

wrote...

Home Search Q & A Board Gallery Resource Library Blog Dictionary Chat	Quick Links Start a Topic Latest Topics Unanswered Questions Courses Study Tools Browse by Textbook	Social Facebook YouTube Community Stats Who's Online Trending Staff	Help About Us Take the Tour Study Tips Posting Guidelines Terms and Policies Contact Us
Biology Forums - Study Force © 2010-2024 \| Powered by SMF \| SMF © 2015, Simple Machines \| Sitemap Biology-Forums.com is not affiliated with any publisher. Book covers, title and author names appear for reference only.

A genetics probability question involving conditional probability

Related Topics