Question

Although the entire protocol describes the process by which DNA is extracted from tissues only two of the steps are actually extraction steps. In this context an extraction refers to a step that removes (or extracts) something. These steps are the ones involving phenol and the one involving chloroform. What biological macromolecules are extracted by phenol and which ones are extracted by chloroform?

Answer 1

Phenol extraction is used to remove proteins during DNA extraction, while chloroform is employed to eliminate remaining proteins, phenol and other impurities to purify the DNA further. After cell lysis, DNA is precipitated using ethanol, resulting in a gelatinous mass that can be stored long-term.

Step-by-step explanation:

The process of extracting DNA from cells often includes the use of phenol and chloroform. Phenol extraction is primarily used for the removal of proteins from the nucleic acid solutions. After lysis, proteins are denatured by phenol, effectively separating them from DNA. On the other hand, chloroform extraction serves to further purify the nucleic acid samples by removing traces of phenol as well as any remaining proteins and other contaminants. When the aqueous phase is mixed with chloroform, proteins and other organic compounds partition into the organic phase, or the interface, while the nucleic acids remain in the aqueous phase. This helps in obtaining a cleaner DNA sample.

During extraction, cells are lysed using buffers and enzymes, such as proteases and ribonucleases (RNases), to break apart lipid molecules and degrade unwanted macromolecules. Ethanol is then used to precipitate the DNA, which forms a gelatinous mass. This DNA can be stored at -80°C for extended periods.