How to solve restriction mapping problems?

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Discussion Overview

The discussion revolves around solving a restriction mapping problem involving a linear DNA sequence that has been digested by multiple restriction enzymes. Participants are exploring how to construct a restriction map based on the sizes of DNA fragments produced by individual and combined enzyme digestions.

Discussion Character

  • Homework-related
  • Exploratory
  • Technical explanation

Main Points Raised

  • One participant expresses confusion about how to piece together the fragment sizes to construct a restriction map, specifically referencing the digestions by enzymes E and B.
  • Another participant points out that the problem statement lacks a clear question and suggests that the absence of a 450 bp fragment in the E + B combination might indicate a restriction consequence.
  • A later reply encourages the original poster to draw different possible maps consistent with the E, B, and E+B digests and to consider the additional enzymes to refine the possibilities.
  • Participants discuss the implications of fragment sizes and how they relate to the positions of restriction sites, with one suggesting that enzyme E must have cut into the 450 bp fragment.

Areas of Agreement / Disagreement

Participants do not reach a consensus on how to construct the restriction map, and multiple approaches are suggested without resolution. There is ongoing uncertainty about the implications of the fragment sizes and how to integrate the information from different enzyme digests.

Contextual Notes

The discussion highlights limitations in the problem statement, including the lack of a specific question and potential missing assumptions about the relationships between fragment sizes and enzyme cuts.

foldedelephants
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Homework Statement


A piece of linear DNA 1000bp long is completely digested by four enzymes, E, B, P, and S.
We are given the sizes of fragments (in bp) produced when each of the enzymes are used in isolation, and when they are used in different combinations:
E : 227, 773
B : 150, 450, 400
P : 400, 600
S : 206, 794
E + B : 223, 227, 400, 150
E + P : 227, 373, 400
B + S : 56, 150, 344, 450
P + S : 194, 206, 600

Homework Equations


Not applicable

The Attempt at a Solution



I understand that with E + B, for example, as 227, 400, and 150 bp are present, enzyme B must have cut the 773 fragment into three pieces, 223, 400, and 150. I really don't know how to piece this information together to make a restriction map, it doesn't make any sense to me.
 
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Hello foldy, :welcome:

The problem statement is missing a question. Could it be it's incomplete ?
You seem to know what a restriction map is; could you elucidate ?

In the mean time I notice E+B has no 450 base-pair sized chunks. Could that be the consequence of one of the restrictions ?
 
BvU said:
Hello foldy, :welcome:

The problem statement is missing a question. Could it be it's incomplete ?
You seem to know what a restriction map is; could you elucidate ?

In the mean time I notice E+B has no 450 base-pair sized chunks. Could that be the consequence of one of the restrictions ?
Thanks for your reply!
Yes, apologies for that, there isn't a question as such; I need to construct a restriction map from this data. My question is how do I do this?
A restriction map shows all the positions of the restriction sites in a piece of DNA, which has information such as the length of the fragments and the enzyme responsible for each restriction site.
Yes, I think that with the E + B combination, enzyme E must have cut into the 450 fragment, dividing it into 227 bp and 223 bp. I'm just not sure how to go from recognising points such as these to constructing the full restriction map.
 
Can you try drawing the different possible maps that are consistent with the E, B, and E+B digests? After you have those possibilities, consider the other two restriction enzymes and use those data to try ruling out some of the maps.
 

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