Plasmid/restiction maps.. am I doing them right?

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boogaaaaa
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Plasmid/restiction maps.. am I doing them right?

Post by boogaaaaa » Mon Nov 09, 2009 3:58 am

Image

here I have drawn a plasmid map from the information presented, however I don't know if i am doing it wrong, so I was wondering if someone could check over my work.

break down: in base pairs
BamHI
900 (0-900)
1500 (900-2400)
3000 (2400-5400)

HindIII
500 (0-500)
1600 (3800-5400)
3300 (500-3800)

BamHI + HindIII
300 (500-800)
400 (5000-5400)
500 (0-500)
1200 (3800-5000)
3000 (800-3800)

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JackBean
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Post by JackBean » Mon Nov 09, 2009 4:19 am

Sorry, but you are wrong :) :(

You assume, that both enzymes cut at position 1, but that's wrong (at least, they can't cut at the same place ;) )

Probably the easiest way will be to start from the largest. The 3000 must come from 3300 of HindIII or 3000 of BamHI, in the second case, there must not be any cut place of HindIII in that piece, that is, the 3000 piece must be in 3300 piece. But than you had to get some two bands of 0 - 300 and 300 - 0, what you don't (yes, you get 300, but than the enzymes had to cut in the same place again), so, back to the first choice, let's say, your plasmid starts with the HindIII position, another HindIII position is at 3300 and at 3000 is BamHI cut place. So, the other BanHI can be at 600 or 1200 from the HindIII position at 3300.
In the first case, there had to be the HindIII place 500 bp far away, but that would result in another 100 bp piece, what you don't get.
In the second case, you may get the 1200 piece and afterwards you get 400 bp piece into another HindIII cut place (in single cut giving 1600 bp).
And so on and so on ;) Try to finish, I have a little be lost ;)
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boogaaaaa
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Re: Plasmid/restiction maps.. am I doing them right?

Post by boogaaaaa » Mon Nov 09, 2009 4:43 am

Thank you for your help and time.

Just one more question, from what I gathered each of those two enzymes can only cut in one place and there cannot be an overlap of cuts (like I did). So in the end after I am done I should end up with all the values from the three columns on my map, correct? (ie 1200,1500,1600,900)

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JackBean
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Post by JackBean » Mon Nov 09, 2009 6:31 am

Check the restriction sites of both enzymes, they should not overlap ;)

Not sure, if I understand to your question, but probably yes. Also, in the double digest, you get only 5 bands, but in both single digests you get three, so one band in double digest comes from 2 places of the plasmid ;)
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