Category: Science > Biology
Asked by: jennifer1000-ga
List Price: $2.00
04 Oct 2004 22:29 PDT
Expires: 03 Nov 2004 21:29 PST
Question ID: 410451
In cattle, the hornless condition is called polled and is due to a dominant gene, while having horns results from a homozygous recessive condition. The red and white coat colors are intermediate and give a roan color when the fenes are heterozygous. What is the phenotypic ratio of a cross between two cattle heterzygous for both horns and color?
Re: Genetic Formula
Answered By: librariankt-ga on 05 Oct 2004 06:27 PDT
Hi Jennifer, Here's what I'll call our gene alleles this time: Polled (dominant): P vs. hornless (recessive): p Red: R vs. white: r - remember that you have three possible phenotypes for color: RR=red Rr=roan and rr=white Like in the guinea pigs question, we have two heterozygous animals producing offspring: PPRR (1) - Polled, red PPRr (2) - Polled, roan PPrr (1) - Polled, white PpRR (2) - Polled, red PpRr (4) - Polled, roan Pprr (2) - Polled, white ppRR (1) - horned, red ppRr (2) - horned, roan pprr (1) - horned, white So now we just need to count up the numbers in parentheses to determine the ratio. Since we have not four phenotypes (as with the guinea pigs) but six, things are a bit more complicated: Polled, red - 3 Polled, roan - 6 Polled, white - 3 Horned, red - 1 Horned, roan - 2 Horned, white - 1 Again, check those basic Mendelian genetics links that I gave you earlier for more help on genetic crosses using incomplete dominance - or ask for more clarification if you need it! I really enjoy these brain teasers, as I think of them, possibly because I don't have to do them for school any more! ;) Librariankt
|jennifer1000-ga rated this answer: and gave an additional tip of: $1.00|
Re: Genetic Formula
From: politicalguru-ga on 05 Oct 2004 01:13 PDT
Thank you for your question. However, I believe that to answer it well, your question will require more time and effort than the average amount of time and effort associated with this price. Here is a link to guidelines about pricing your question, in the pricing guide: https://answers.google.com/answers/pricing.html
If you feel that you have found inappropriate content, please let us know by emailing us at firstname.lastname@example.org with the question ID listed above. Thank you.
|Search Google Answers for|