Question:

During the purification process for recombinant DNA technology, addition of chilled ethanol precipitates out :

Updated On: Nov 14, 2025

RNA
DNA
Histones
Polysaccharides

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The Correct Option is B

Solution and Explanation

The process of using chilled ethanol in recombinant DNA technology is crucial in the purification of DNA. When DNA solutions are treated with chilled ethanol, the ethanol reduces the solubility of DNA in water, which causes the DNA to precipitate out of the solution. Here's how this method works step by step:

Principle: Ethanol is a non-polar solvent, and DNA is a polar molecule due to its charged phosphate backbone. When ethanol is added to a DNA solution, it reduces the solution's polarity, leading to the precipitation of DNA.
Temperature: The ethanol used is chilled to maximize the precipitation. Chilling helps in reducing the solubility of DNA and other macromolecules.
Separation: DNA, being a large molecule with a high molecular weight, precipitates more readily compared to other molecules like RNA, proteins (histones), and polysaccharides. These smaller molecules remain soluble.
Other Molecules: While RNA may also precipitate to a certain extent, specific conditions or additional steps can be used to selectively precipitate DNA over RNA, such as altering the ionic strength of the solution or using additional purification steps after the ethanol precipitation.

Therefore, during the purification process for recombinant DNA technology, the addition of chilled ethanol primarily precipitates out DNA. The reasoning behind this involves the principle of solubility and the molecular properties of ethanol and DNA.

In conclusion, the correct option is DNA, as chilled ethanol specifically aids in its precipitation, facilitating the purification process in recombinant DNA technology.

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Concepts Used:

Recombinant Technology

Recombinant DNA technology is the process used for producing new genetic combinations by joining different genetic material (DNA) together and inserting them into host organisms from two different species or sources. These new combinations are of value to medicine, science, industry, and agriculture.

Process of Recombinant DNA Technology:

Step 1- Isolation of Genetic Material.

Step 2- Cutting the gene at the recognition sites.

Step 3- Amplifying the gene copies through Polymerase chain reaction ( PCR)

Step 4- Ligation of DNA Molecules.

Step 5- Insertion of Recombinant DNA into Host.

Application of Recombinant DNA Technology:

In agricultural fields Recombinant DNA Technology plays a major role. It produces genetically-modified organisms such as flavor save tomatoes, golden rice rich in protein and lot more
Recombinant DNA technology is also used to produce Insulin.
ELISA is one kind of clinical diagnosis where recombinant DNA technology is used.
Recombinant DNA technology prevents hereditary diseases through gene therapy and also detects the presence of HIV in a person.