Read the passage and answer the following question :

After cutting DNA with restriction endonucleases, the resulting fragments can be separated using a technique called gel electrophoresis. This process takes advantage of the negative charge of DNA molecules, causing them to move towards the anode in an electric field through a matrix, commonly made of agarose, a natural polymer derived from seaweeds. The agarose gel acts as a sieve, allowing smaller DNA fragments to move farther than larger ones. To visualize the separated DNA fragments, the gel is stained with ethidium bromide and exposed to UV radiation, resulting in bright orange-colored bands. These bands represent the different sizes of DNA fragments. The specific bands of interest are carefully cut out from the gel, and the DNA is extracted from the gel piece. This step is called elution. The purified DNA fragments obtained through elution are then used to construct recombinant DNA by joining them with cloning vectors. This process enables scientists to study, manipulate, and replicate specific DNA sequences for various applications in genetic engineering and molecular biology.

What is elution ?

Cutting of separated DNA fragments from agarose gel and extraction of DNA fragment.

The correct answer is Option (4) -Cutting of separated DNA fragments from agarose gel and extraction of DNA fragment.

The process of cutting DNA using restriction endonucleases results in the formation of DNA fragments. These fragments can be separated using a technique called gel electrophoresis.

Since DNA fragments are negatively charged molecules, they can be separated by applying an electric field, causing them to move towards the anode through a medium or matrix. Agarose, a natural polymer extracted from seaweeds, is commonly used as the matrix. The DNA fragments separate based on their size due to the sieving effect provided by the agarose gel. Smaller fragments move farther compared to larger fragments.

The separated DNA fragments can be visualized only after staining the DNA with a compound called ethidium bromide, followed by exposure to UV radiation. Without staining, the pure DNA fragments cannot be seen in visible light. After staining, you can observe bright orange-colored bands of DNA in an ethidium bromide stained gel exposed to UV light.

Once the DNA fragments are separated, they can be cut out from the agarose gel and extracted from the gel piece. This step is known as elution. The purified DNA fragments obtained through elution are then used in constructing recombinant DNA by joining them with cloning vectors.