Gene Mapping Question

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greenpak07
Garter
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Joined: Sat Nov 29, 2008 11:42 pm

Gene Mapping Question

Post by greenpak07 » Sat Nov 29, 2008 11:48 pm

Hi guys,
I'm new here, I found this site while trying to look for help with bio questions, and it helped me.
I'm just trying to learn gene mapping and I'm a bit confused as to why the answer this question is D. I don't understand how they determined which gene is in the middle,I just don't get it, I'd really appreciate it if someone could help work it through so I'd understand how they got that answer to be wrong and the other one's to be right. For someone who's just learned this, it's really hard to work backwards, so I'd appreciate any type of help.

Esmé has her Bio199 project planned. She will determine the map distance between the
tubby and vestigial genes in Drosophila.

tb+ normal, long body
tb tubby, short body
vg+ big wings
vg small wings

She began by crossing true-breeding, homozygous parents and picking an F1 female from
this cross to testcross.
Esmé generated the following table of the progeny from the testcross:
Observed phenotype number
normal, long body and big wings 283
normal, long body and small wings 1294
tubby, short body and big wings 1418
tubby, short body and small wings 241
Which of the following statements is not true about this experiment?
A. The recessive alleles of the F1 heterozygous female were in trans.
B. The F1 heterozygous female genotype was tb+ vg/tb vg+.
C. The frequency of recombination was 16%.
D. vg is 19 map units from tb.
E. All of the statements are true.

Cat
King Cobra
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Post by Cat » Sun Nov 30, 2008 8:19 pm


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