Question

Explain the process of separation and isolation of DNA fragments by a typical gel electrophoresis.

Hint:

Remember: In gel electrophoresis, smaller DNA fragments travel faster than larger ones.

Answer 1

Gel electrophoresis is a widely used technique to separate DNA fragments based on size. The process involves the following steps:

1. A gel matrix (usually agarose) is prepared and submerged in an electrophoresis chamber. DNA samples are loaded into wells at one end of the gel.
2. An electric current is applied across the gel, and DNA, which is negatively charged, moves towards the positive electrode.
3. The gel acts as a sieve, allowing smaller DNA fragments to move faster through the matrix than larger ones, thus separating them based on size.
4. After electrophoresis is completed, the DNA fragments are stained with a dye (like ethidium bromide), and the gel is exposed to UV light, allowing visualization of the separated fragments as bands.

This method helps in analyzing DNA for various purposes, such as DNA profiling, gene cloning, or identifying mutations.