Question

What do you understand by Gel Electrophoresis? Explain it.

Hint:

Same principle as Q5(c): smaller fragments travel further under the electric field.

Answer 1

Step 1: What it is used for:
Gel electrophoresis is a laboratory technique used to separate a mixture of DNA (or RNA/protein) fragments by size, which is an essential step in many recombinant DNA technology procedures, such as checking the products of a restriction digestion or a PCR reaction.

Step 2: How it works:
The negatively-charged DNA fragments are loaded into wells of an agarose gel and an electric field is applied; the fragments migrate towards the positive electrode, with smaller fragments moving faster and farther through the gel matrix than larger ones, so the mixture resolves into separate bands ordered by size.

Step 3: After separation:
The separated DNA bands are stained (e.g. with ethidium bromide) and visualised under UV light; if needed, a specific band of interest can then be cut out of the gel and eluted for further use, such as cloning.

Final Answer:
Gel electrophoresis separates DNA fragments by size using an electric field, and the resulting bands can be visualised and, if required, extracted for downstream use such as cloning.