Assertion:  In order to cut the DNA with restriction enzymes, it needs to be in pure form, free from other macro-molecules.
Reason: The RNA can be removed by treatment with ribonuclease whereas proteins can be removed by treatment with protease.

Both Assertion (A) and reasoning (R) are correct and but R is not the correct explanation of A.

The correct answer is Option (2)- Both Assertion (A) and reasoning (R) are correct and but R is not the correct explanation of A.

In majority of organisms this is deoxyribonucleic acid or DNA. In order to cut the DNA with restriction enzymes, it needs to be in pure form, free from other macro-molecules. Since the DNA is enclosed within the membranes, we have to break the cell open to release DNA along with other macromolecules such as RNA, proteins, polysaccharides and also lipids. This can be achieved by treating the bacterial cells/plant or animal tissue with enzymes such as lysozyme (bacteria), cellulase (plant cells), chitinase (fungus). Genes are located on long molecules of DNA interwined with proteins such as histones. The RNA can be removed by treatment with ribonuclease whereas proteins can be removed by treatment with protease.