Question

During the process of isolation of DNA, chilled ethanol is added to

• A. Facilitate action of restriction enzymes
• B. Precipitate DNA
  
• C. Break open the cell to release DNA
• D. Remove proteins such as histones

Answer 1

The correct option is B Precipitate DNA


Isolation of the gene of choice
The first step in forming the rDNA is isolating the gene of choice from the cell. The extraction of the gene of choice from the cell is done in the following way:-

• Breaking the cell wall (B) - Enzymes are used to break the cell wall. The choice of the enzyme is based on the component of the cell wall. The genetic material of the cell is released in this way.
• Treatment with proteases and ribonucleases (D) - Removal of proteins (histones) and RNA that are associated with the DNA is done with proteases and ribonucleases respectively.
• DNA precipitation- Chilled ethanol is used to precipitate DNA from the cell membrane, proteins, and RNA fragments.
• Mixing with restriction enzymes (C) - The DNA is spooled and mixed with restriction enzymes so that the enzyme can cleave the DNA at specific sites.
• Electrophoresis- The DNA fragments are then separated based on their size using an electric field in agarose gel electrophoresis.
• Gel elution- The DNA of choice is then separated from the gel using certain techniques collectively called gel elution.

Final answer
(A) Precipitate DNA