How do scientists isolate DNA in order to study it?

Hint: All the information (genetic) related to an organism is carried in the DNA molecule. Macromolecules such as DNA, RNA, and proteins can be extracted from the body of an organism. Once these macromolecules are extracted their structure and other aspects of these macromolecules can be thoroughly studied. The macromolecule (DNA) can be purified and cloned. It can also be used to create recombinant DNA.

Complete answer:
DNA was first extracted by Friedrich Miescher. Initially,it was quite difficult to study the long nucleotide chains of the DNA molecule. Today, however, DNA extraction and isolation is the most common and easiest method employed in molecular studies.
The first step taken to extract DNA is breaking the cell membrane. Depending upon the cell membrane composition, cells can be lysed by chemicals such as enzymes. Some equipment such as sonicators (use ultrasonic frequency to break open the cell) can also be used.
The DNA now needs to be separated from the cell debris. The mixture can be centrifuged to separate DNA molecules from the cell debris (will sediment at the bottom of the centrifuge tube). RNAse can be used in case RNA is present in the mixture.
Now the proteins attached to the DNA must be removed from the mixture. Proteases act on the proteins. These protein molecules denature. They are then precipitated using organic solvents. The second round of centrifugation follows.
DNA obtained is washed with alcohol. This process further purifies the DNA. This is not the only way to isolate DNA from other contents. This is, however, one of the most common methods employed.

Note: It is also possible to isolate a gene of interest from the DNA molecule. This can be done using specific restriction nucleases. These nucleases cut the DNA into smaller fragments. These smaller DNA fragments can be amplified. Polymerase chain reaction can be used to amplify genes of interest. PCR is used in the medical field, forensic sciences, etc.