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biology a level question

help
(edited 3 years ago)
Are you stuck on any part of this in particular? How much of this do you already understand and what do you need help with?

As a start :
1. You are given the sizes of the fragments P-S, what do you know about how DNA fragments separate when run like this?
2. Without seeing the info that this question (presumably) provides - is AAGCTT the site at which HindIII digests? If so, then how many times must it have digested to result in the number of DNA fragments that it did?
3. Does it tell you the size of the untreated DNA? (Probably not.) If not, estimate based on the size of P.
4. If one of the digestion sites changes, will the enzyme be able to digest it? Therefore how many fragments would there be?
Reply 2
Original post by TheVirtualPhoton
Are you stuck on any part of this in particular? How much of this do you already understand and what do you need help with?

As a start :
1. You are given the sizes of the fragments P-S, what do you know about how DNA fragments separate when run like this?
2. Without seeing the info that this question (presumably) provides - is AAGCTT the site at which HindIII digests? If so, then how many times must it have digested to result in the number of DNA fragments that it did?
3. Does it tell you the size of the untreated DNA? (Probably not.) If not, estimate based on the size of P.
4. If one of the digestion sites changes, will the enzyme be able to digest it? Therefore how many fragments would there be?

are you able to give me some more hints please
Difficult to give hints without knowing what it is you're struggling with and what you already know.

HindIII is a restriction enzyme that digests DNA at AAGCTT sequences. That has been done here with the DNA on track 1. The DNA on track 2 hasn't been digested with the enzyme so is the original size.
When digested DNA is run on a track like this, the fragments separate by size so that the smallest fragment travels the furthest and the largest fragment travels the shortest distance.

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