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

The correct answer is Histones.

Explanation:

During the isolation and purification of recombinant DNA, nucleic acids (DNA) are extracted from cells along with various cellular contaminants such as proteins, RNA, and polysaccharides.

To obtain purified DNA, specific enzymes are used to degrade other macromolecules:

1. Proteases are added to digest proteins, including histones (the basic proteins bound to DNA in eukaryotic chromosomes).

2. Ribonucleases (RNase) are used to remove RNA.

After treatment with these enzymes, chilled ethanol is added to the purified solution. DNA is insoluble in cold ethanol, so adding chilled ethanol causes the purified DNA to precipitate out as fine threads. This process is commonly collected by spooling.

Therefore, addition of chilled ethanol specifically precipitates out DNA (while Histones and other proteins are removed earlier by protease digestion and remain in solution or degraded form). Note: Based on standard recombinant DNA procedures, DNA precipitates upon addition of chilled ethanol.