A ladder of 5000, 3000, 2000, 1000 and 500 bp runs 10.2, 13.3, 15.8, 20.0 and 24.2 mm from the well…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A ladder of , , , and bp runs , , , and mm from the well. A straight line fits against the distance: . A student reads two unknown bands, at mm and at mm.
- What is the size of the band at mm?
- What is the size of the band at mm?
- Is a band at mm safe to read from this ladder?
Need a reminder? The key ideaShow
Read a size from a ladder with a straight line of size against distance. An uncut plasmid shows a supercoiled band (fastest), a linear band and a nicked band (slowest). The control plates are: no DNA, uncut vector, cut vector without ligase, and cut vector with ligase and no insert. Efficiency colonies (ng of DNA on the plate) for each microgram.
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. The line .
Plan. Find the log of the size, and then the size.
Step 1. (a) . The size is bp.
Step 2. (b) . The size is bp.
Step 3. (c) The ladder runs from to mm. A band at mm is beyond the smallest ladder band, so the line is not tested there. The reading would be a guess.
Answer: bp; bp; no, mm lies outside the ladder.
Check. mm lies between the bp band at mm and the bp band at mm, and lies between and .
More onBiotechnology
Discussion (0)
Log in to join the discussion.
Loading…