Question

a) How do DNA fragments migrate and resolve in a Gel electrophoresis?
b) How lane one is different from lane 2, 3 and 4 in the Gel electrophoresis set up?
c) How pure DNA fragments are made observable in the visible light?

Answer 1

A) In gel electrophoresis, wells are dug in which the restriction fragments are placed. The side near the wells is connected to the cathode( -vely charged) and the opposite end is connected to the anode( +vely charged)

Since DNA is negatively charged, it will be will attracted to the anode (or the positively charged terminal)

Also in DNA, the chances of the restriction sequence to occur is high and it can be placed at any loci. So different lengths of DNA fragments will also be present.

Electricity is allowed to pass. The long DNA fragments will travel slowly and thus are closer to the wells while the shorter fragments are closer to the anode. This is how the migration of DNA fragments occur.

C) Ethidium bromide is added and observed under uv lights. The DNA fragments ate now visible.

Hope this is helpful :)

Answer 2

Answer:

(a) The DNA fragments resolve according to their size through sieving effect provided by the agarose gel. Hence, the smaller the fragment size, the farther it moves. (b) The given agarose gel electrophoresis shows migration of undigested DNA fragments in lane 1 and digested set of DNA fragments in lane 2 to 4.