Explain the method for the separation and isolation of $DNA$ fragments.

(N/A) 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 sea weeds. The $DNA$ fragments separate according to their size through the sieving effect provided by the agarose gel. Hence,the smaller the fragment size,the farther it moves. Look at the figure and guess at which end of the gel the sample was loaded.
Separated $DNA$ fragments can be visualized only after staining the $DNA$ with a compound known as ethidium bromide followed by exposure to $UV$ radiation (you cannot see pure $DNA$ fragments in the visible light and without staining).
Bright orange-colored bands of $DNA$ can be observed in an ethidium bromide-stained gel exposed to $UV$ light (see figure). The separated bands of $DNA$ are cut out from the agarose gel and extracted from the gel piece. This step is known as $elution$. The $DNA$ fragments purified in this way are used in constructing recombinant $DNA$ by joining them with cloning vectors.