Read the Passage carefully and answer the questions.

There are two kinds of nucleases - exonucleases and endonucleases. Exonucleases remove nucleotides from the ends of the DNA whereas, endonucleases make cuts at specific positions within the DNA. 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. Small volume cultures cannot yield appreciable quantities of products. To produce in large quantities, the development of bioreactors, where large volumes (100-1000 litres) of culture can be processed, was required. Thus, bioreactors can be thought of as vessels in which raw materials are biologically converted into specific products, individual enzymes, etc., using microbial plant, animal or human cells. PCR stands for Polymerase Chain Reaction. In this reaction, multiple copies of the gene (or DNA) of interest are synthesised in vitro using two sets of primers (small chemically synthesised oligonucleotides that are complementary to the regions of DNA) and the enzyme DNA polymerase.

Which one of the following statements is correct about DNA separation and isolation?

DNA fragments are negatively charged and move towards anode under the electic field.

The correct answer is Option (3) → DNA fragments are negatively charged and move towards anode under the electic field. 

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.