Sequence of genes

[RHONDAROBINSON]

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Is anyone familiar with gene sequencing? Take a look at this question.


Choose the correct sequence of genes given the following recombination frequencies.

A-B, 20 map units
A-C, 15 map units
A-D, 20 map units
D-C, 30 map units

Answer Choices:

A. A-B-C-D
B. B-C-A-D
C. C-A-D-B

rr

 

[Ex_EE]

Is there a choice D. None of these are correct.

 

[RHONDAROBINSON]

The answer is B-C-A-D according to the DAT Achiever. I do not understand the explanation given which is a diagram as follows:

___________15_________20
B.......C........A...................D
------20-----------
____________35__________



rr

 

[Ex_EE]

The diagram they provided doesn't match the question. It is really simple based on the answer and diagram the question should be:
A-B, 20 map units
A-C, 15 map units
A-D, 20 map units
D-C, 35 map units

 

[nate28]

The question if flawed.

A-B = 20
A-C = 15
A-D = 20
C-D = 30

If A-C is 15, and A-D is 30, then C-D must be either 15 or 45. But they say C-D is 30.

 

[Ex_EE]

The question if flawed.

A-B = 20
A-C = 15
A-D = 20
C-D = 30

If A-C is 15, and A-D is 30, then C-D must be either 15 or 45. But they say C-D is 30.

Where did you get A-D 30? But, yes I agree the question is flawed.

 

[nate28]

The question if flawed.

A-B = 20
A-C = 15
A-D = 20
C-D = 30

If A-C is 15, and A-D is 30, then C-D must be either 15 or 45. But they say C-D is 30.

My bad. A-D is not 30, it's 20 as the problem states.
So C-D should be either 5 or 35. Sorry about that.

 

[Streetwolf]

Except research isn't always exact and so the BEST answer is B.

 

[smec]

The diagram they provided doesn't match the question. It is really simple based on the answer and diagram the question should be:
A-B, 20 map units
A-C, 15 map units
A-D, 20 map units
D-C, 35 map units

I just looked up on my achiever and the map units you deduced are exactly like what the question gives. Rhonda has got the last row typed wrongly and I believe those linings on the diagram have been left justified, making them rather confusing at first glance.

One needs only to arrange those letters such that the units given will all match. It's just as simple as it is and don't complicate the whole thing.

 

[RHONDAROBINSON]

Thanks for the clarification SMEC. The lines are off a little. I now understand why the answer is what it is just by this mix up of the lines. Thanks all.


rr

 

[Moka11]

I stumbled across this questions and I never learned it. Where do I begin? (Its not in Cliffs IIRC)

 

[IsaacYankem]

I stumbled across this questions and I never learned it. Where do I begin? (Its not in Cliffs IIRC)

Pages 96-97 in Cliff's 3rd edition. Also:

http://www.youtube.com/watch?feature=player_detailpage&v=YYswTvuwxmg#t=414s