Final answer:
To precipitate DNA from an aqueous solution during extraction, protease and RNAase are used to remove proteins and RNA, then ethanol or isopropanol is added to precipitate DNA, resulting in white strands that can be collected. The DNA is then washed, dried, and resuspended for further use.
Step-by-step explanation:
To precipitate DNA from an aqueous solution during extraction, a series of steps are followed to ensure that the DNA is isolated from other cellular components.
Cell contents are treated with protease to destroy protein, and RNAase to destroy RNA.
Cell debris is then pelleted in a centrifuge, and the supernatant containing the DNA is transferred to a clean tube.
To precipitate the DNA, ice-cold ethanol or isopropanol is added to the aqueous solution containing the DNA. Upon adding the alcohol, you will observe white, viscous strands of DNA that can be spooled or gathered on a glass rod.
The precipitated DNA can then be washed with 75% ethanol to remove any remaining salts and impurities.
After the wash, the DNA is dried and can be resuspended in a suitable buffer such as TE buffer for further use.
This process of DNA precipitation is crucial in molecular biology for studying genetic material, where pure DNA is required for various analytical techniques.