A straight DNA is 9000 base pairs long. Enzyme A cuts it at 1500 bp and at 4200 bp, measured from…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A straight DNA is base pairs long. Enzyme A cuts it at bp and at bp, measured from the left end. Enzyme B cuts it at bp and at bp. The two enzymes do not cut at the same place.
- How many fragments does enzyme A give, and what is the size of the largest?
- How many fragments does enzyme B give, and what is the size of the largest?
- The DNA is cut with both enzymes together. What is the size of the smallest fragment, and how many fragments are there?
Need a reminder? The key ideaShow
A restriction endonuclease cuts both strands inside its palindromic recognition sequence. A site of bases turns up by chance about once in bases. A straight DNA with sites gives fragments. A circular DNA with sites gives fragments.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Length bp. A: and . B: and .
Plan. Put the cuts in order, with and at the two ends. The gaps are the fragment sizes.
Step 1. (a) Enzyme A: , , and . That is fragments, and the largest is bp.
Step 2. (b) Enzyme B: , and . That is fragments, and the largest is bp.
Step 3. (c) The cuts in order: , , , . Fragments: , , , and bp. That is fragments. The smallest is bp.
Answer: A: fragments, bp largest. B: fragments, bp largest. Both: fragments, bp smallest.
Check. bp. The pieces add up to the whole.
More onBiotechnology
Discussion (0)
Log in to join the discussion.
Loading…