Observe the given figure and name the step used in Recombinant DNA Technology.

Spooling

The correct answer is Option (4) –Spooling

DNA that separates out can be removed by spooling .

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. Other molecules can be removed by appropriate treatments and purified DNA ultimately precipitates out after the addition of chilled ethanol. This can be seen as collection of fine threads in the suspension.

DNA spooling is a technique used to collect DNA in the form of a spool on a glass rod, representing the final step of DNA extraction. In this process, ethanol is added in the last step to precipitate the DNA. Once the DNA is precipitated, a thin glass rod is inserted into the tube containing the DNA. By gently rotating the glass rod with the fingers, the DNA adheres to the rod and can be collected.