Gel Electrophoresis MCQ - Practice Questions & Answers

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Agarose extracted from seaweeds finds use in:

Spectrophotometry

Tissue culture

PCR

Gel electrophoresis

DNA fragments generated by the restriction endonucleases in a chemical reaction can be separated by:

Restriction mapping

Centrifugation

Polymerase chain reaction

Electrophoresis

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Gel Electrophoresis

The term gel electrophoresis refers to a technique used for separation and analysis of DNA, RNA, and proteins based on their size and charge.
The cutting of DNA by restriction endonucleases results in the fragments of DNA.
These fragments can be separated by a technique known as gel electrophoresis.
Since DNA fragments are negatively-charged molecules they can be separated by forcing them to move towards the anode under an electric field through a medium/matrix.
Nowadays the most commonly used matrix is agarose which is a natural polymer extracted from seaweeds.
The DNA fragments separate (resolve) according to their size through sieving effect provided by the agarose gel.
Hence, the smaller the fragment size, the farther it moves.
The separated DNA fragments can be visualized only after staining the DNA with a compound known as ethidium bromide followed by exposure to UV radiation\
Bright orange colored bands of DNA in an ethidium bromide-stained gel exposed to UV light will be seen.
The separated bands of DNA are cut out from the agarose gel and extracted from the gel piece in a step called elution.
The DNA fragments purified in this way are used in constructing recombinant DNA by joining them with cloning vectors.