Purchase Solution

Genetics -- map units

Not what you're looking for?

Ask Custom Question

EDIT to the problem below: I just realized that the various numbers of offspring add up to 9900, not 10,000, which is the supposed total. So for problem #2, I randomly added 100 to my recombinant numbers and got the answer, 30.1, which turned out to be correct.

But the same thing did not work for problem #1. Adding 100 to the recombinant numbers resulted in an answer of 1.2, which is not correct. Nor is the correct answer 1.1, which would make up the distance between 30.1 -- 29 (the distane from sp-cn minus the distance from px-cn.)

So here are my questions about this new twist: 1) Why would 100 offspring be left out of the various classes of offspring. How is this a reflection of what happens in real life experiments? 2) How do you know where to add the 100 offspring in and where not to? The distance between px-cn didn't need the extra 100. And the distance between sp-cn did. 3) And why isn't any of this working for the distance between px-sp?

Thank you!!

Hi. I can't figure out this problem:

Females heterozygous for the recessive second chromosome mutations pn, px, and sp are mated to a male homozygous for all three mutations. The offspring are:

px sp cn 1410
px sp + 3498
px + cn 1
px + + 11
+ sp cn 8
+ sp + 0 (none seen)
+ + cn 3483
+ + + 1489
-----
10,000 total

I correctly figured out that the middle gene is px.
I correctly figured out that the distance between
px-cn is 20 m.u.

But I can't seem to figure out 1) the distance between
px-sp or 2) the distance between sp-cn.

Here's what I'm doing:

First, I assigned the following types to the above listed classes, in the order that they are listed above:

SCO (single crossover)
P (parental)
DCO (double crossover)
SCO
SCO
DCO
P
SCO

1) To figure out the RF of px-sp: [(1 + 11 + 8 + 0) / 10,000] x 100 = 0.2 m.u.

1) To figure out the RF of sp-cn: [(1410 + 11 + 8 + 1489) / 10,000] x 100 = 29.18 m.u.

But neither one of those answers is correct.

Can you please explain how to do this problem?

Thank you.

Purchase this Solution

Solution Preview

I would expect that this is a typo in the question. You should not have to guess about the "missing" 100 offspring. While a real experiment is not likely to give such a nice, round number as 10000, a (honest) researcher would never add in numbers that were not there. Finally, I think you switched the numbers of px sp cn and px sp +, as well as + + cn and + + +, in the numbers you gave me (at least based on your attempts at the problem).
<br><br>So, if px sp + is 1410, and + + cn is ...

Purchase this Solution


Free BrainMass Quizzes
Pregnancy Knowledge

How much do you know about being pregnant? Test your Pregnancy IQ with this quiz!

BIOLOGY

Basics in biology

Labor Comfort Measures

Do you know how to comfort someone in labor?

How Much Do You Know About Genetic Inheritance?

Most of us studied the basics of dominant and recessive genes at some point. However, genetics are much more complicated than this. How far beyond the basics does your knowledge go?

BioChemistry Basics

This Quiz will test your knowledge of the amino acids used in biological systems