Which of the following is added to precipitate out DNA during its isolation from a cell tissue?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Chilled ethanol
Option (3) Chilled ethanol — Correct. After the cell walls, RNA and proteins are removed, chilled ethanol is added. The purified DNA precipitates out and can be seen as fine threads.
NCERT Extract:
Isolation of the Genetic Material (DNA) – “… You know that genes are located on long molecules of DNA interwined with proteins such as histones. The RNA can be removed by treatment with ribonuclease whereas proteins can be removed by treatment with protease. Other molecules can be removed by appropriate treatments and purified DNA ultimately precipitates out after the addition of chilled ethanol. This can be seen as collection of fine threads in the suspension (Figure 9.5).”
Figure 9.5 DNA that separates out can be removed by spooling