Question

• What is the purpose of gel electrophoresis?
• How is size related to movement through a gel?
• What is a DNA ladder? Why is it important in gel electrophoresis and how is it used? (note: a ladder is also called a “standard”)
• What are two indications one can look for to be certain the gel electrophoresis is occurring?
• What are two strategies to improve the resolution of DNA bands?

Answer 1

1. The purpose of gel electrophoresis is to differentiate the DNA according to its size.It is generally done in various research purpose to identify and isolate the desirable DNA fragment.

2.In gel electriphoresis the smaller DNA fragments will move faster and the larger ones slower.So the smaller fragments will be present at the bottom & the larger will be at the top accordingly to their size.

3.The DNA ladder is a standard size fragment which contains every the standard size of fragments.

It is used to differentiate the diserable DNA fragment from the whole sample DNA.

4.There are two main indicatiors-(a) the size of the sample DNA fragment according to the ladder(standard). (b)the DNA fragment band width of the sample.

5. To improve the resolution- (a) Use the purified sample DNA. (b)use the cast thin gel(1-2% agaros gel conc.is also vey effective)