How Do Recombination Frequencies Relate to Gene Distance?

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    Genetics Recombination
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Discussion Overview

The discussion revolves around the relationship between recombination frequencies and gene distances on a linkage map, addressing specific questions related to genetic mapping and the implications of recombination frequency values. Participants explore various statements regarding recombination frequencies and their correctness in the context of genetic distance.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • Some participants suggest that a recombination frequency of 1.5% corresponds directly to 1.5 map units, while others challenge this interpretation based on the concept of interference.
  • There is a proposal that recombination frequencies cannot be the same for all genes, as distances between genes vary.
  • Participants express uncertainty about the implications of recombination frequencies increasing with distance, with some arguing that this is not the case.
  • One participant mentions that the distance between genes is the same for cis and trans heterozygotes, while another references literature that supports this claim.
  • Several participants express confusion about the correct answers to the posed questions, with differing opinions on which statements are accurate.
  • One participant indicates that they found material that clarified their understanding, leading them to believe that answer D was correct for one of the questions.
  • There is acknowledgment of the complexity of the questions and the need to interpret them carefully, with some participants admitting to losing track of the specific questions being discussed.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct answers to the questions posed. Multiple competing views remain regarding the interpretation of recombination frequencies and their implications for gene mapping.

Contextual Notes

Some participants reference the concept of interference in relation to recombination frequencies, but the implications of this concept remain unclear. Additionally, there are mentions of external literature that may provide further context but are not universally accepted by all participants.

sonyab523
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Confused on 2 questions hereIf a recombination frequency between two genes is 1.5%, what is the distance between the genes in map units on the linkage map?

a. Impossible to determine, because the interference is not known.
b. 1.5
c. 3
d. 0.75

Recombination frequencies

a. arise from completely random genetic exchange.
b. are the same for all genes.
c. decrease with distance.
d. are the same for cis and trans heterozygotes.I thought it was b for the first part a for the second part and but I'm wrong. Can someone explain?
 
Last edited:
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Sorry forgot to add my explanation

b. Each % frequency of recombination equals one map unit between the genes. So 1.5% recombination frequency = 1.5 map units apart will result in 1.5% recombination

a. It can't be (b), because genes are all distances apart; it can't be (c), because frequencies increase with increasing distance; it can't be (d), because the distance between genes is the same whether the alleles are cis or trans loci. So I thought it was a.
 
Help help please.
 
I'm not absolutely sure, but I'd probably agree with your answers.
 
nobahar said:
I'm not absolutely sure, but I'd probably agree with your answers.

I thought I was right but when I entered it into the system I was wrong. I'm sure the first part is right and I thought the second part was right but I guess not.
 
I would probably agree too. It is a strange way of examining to ask which of four statements is correct. It seems to me though I am a bit rusty, that you have to a little bit psych what some of the questions mean, if it's any consolation.
 
Well that can't be right since it's marked wrong. Anyone think it's c for the second part?
 
I was thinking D and C. D because as the loci become further apart (low recombination values) the probability of a second crossover increases and the recombination value is overestimated. The only value less than 1.5 is 0.75 (D). I don't know what is meant by "interference" in answer A but that could be correct as well.

Edit. you are right C can't be correct
 
  • #10
I finally found some material that helped. I got it right and the answer was D. Thanks guys for your help I really appreciate it.
 
  • #11
I've been talking about question 2.
For which one is the answer D? What did you arrive at for number 2?
The link I recommended explicitly states that trans and cis heterozygotes exhibit equal recombination frequencies.
 
  • #12
nobahar said:
I've been talking about question 2.
For which one is the answer D? What did you arrive at for number 2?
The link I recommended explicitly states that trans and cis heterozygotes exhibit equal recombination frequencies.

D is the answer for the second question. So you were right.
 
  • #13
sonyab523 said:
D is the answer for the second question. So you were right.

My apologies, I lost track of the question! Technically I wasn't right, the textbook was...
 

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