Isopropyl alcohol how to precipitate DNA? Explain its principle and application

DNA extraction and purification is an important step in molecular biology experiments. Isopropyl alcohol (Isopropanol), as a common precipitant, is widely used in the process of DNA extraction. How does isopropanol precipitate DNA? How does it help scientists extract and purify DNA? This article will analyze the principle of this process in depth and discuss its application in DNA extraction.

1. DNA precipitation basic principle

DNA precipitation refers to a process in which DNA is precipitated from a solution to form solid particles by changing the environment of the solution under specific conditions. Commonly used precipitants are ethanol, isopropanol, etc. In DNA extraction, isopropanol is often used as a precipitant, and its role is based on the following principles:

• Decrease the polarity of the solution: DNA molecules are themselves negatively charged, and in aqueous solution, water molecules interact with DNA molecules through hydrogen bonds. After the addition of isopropanol, it reduces the polarity of the solution and weakens the interaction between the DNA molecules and the solvent, causing the DNA molecules to no longer dissolve, thereby forming a precipitate.

• Removal of moisture: Isopropanol interacts with water molecules in aqueous solution, reducing the amount of moisture, weakening the electrostatic repulsion between DNA molecules, and prompting DNA molecules to aggregate and precipitate.

2. Isopropanol Precipitation of DNA Experimental Steps

In DNA extraction, the specific steps of how isopropanol precipitates DNA are usually as follows:

1. Cell lysis: DNA is released by breaking cells through cell lysates or mechanical methods.

2. Removal of impurities: the use of salts, phenols and other methods to remove intracellular proteins and other impurities, leaving free DNA.

3. Isopropanol addition: Add an equal volume of isopropanol to the DNA solution and mix gently. As isopropanol reduces the polarity of the solution, DNA molecules begin to precipitate out of solution.

4. Collection of DNA by centrifugation: The precipitated DNA molecules were collected at the bottom of the tube by centrifugation and the supernatant was removed.

5. Washing and dissolution: The precipitated DNA is washed with 70% isopropanol to remove impurities, and the purified DNA is finally dissolved with an appropriate buffer or water.

Through this process, DNA can be isolated from complex biological samples to obtain a pure DNA sample.

3. Isopropanol in DNA precipitation advantages and challenges

Advantage

• Efficient precipitation of DNA: Isopropanol in the precipitation of DNA, usually can get more complete DNA molecules, compared to ethanol, isopropanol precipitation efficiency is higher, the recovery rate of DNA is also better.

• Low toxicity: Compared with other organic solvents, isopropyl alcohol is less toxic, safer to use, and easier to handle.

• Wide range of applications: The isopropanol precipitation method is suitable for a variety of biological samples, including bacteria, plants, and animal tissues.

CHALLENGE

Although the isopropanol precipitation method has many advantages, there are also some challenges:

• Differences in solubility: The purity of different batches of isopropanol may vary, so during the DNA precipitation process, it may be affected, resulting in inconsistent recovery of DNA.

• The integrity of the precipitation: If the operation is improper, the DNA precipitation may be mixed with other impurities, which will affect the subsequent experimental results. Therefore, the washing step is very critical.

4. Isopropyl alcohol precipitation of DNA practical application

DNA precipitation with isopropanol is widely used, especially in the fields of molecular cloning, genomics research and forensic medicine. Common applications include:

• DNA Extraction: When extracting DNA from cell or tissue samples, isopropanol precipitation provides a simple and efficient method.

• Genomic analysis: When conducting genomic research, it is necessary to extract high-quality DNA samples. Precipitation with isopropanol yields pure DNA, ensuring the accuracy of subsequent analysis.

• PCR and cloning experiments: The extracted DNA samples can be used for polymerase chain reaction (PCR) or gene cloning experiments. Isopropanol precipitation ensures the purity of DNA and helps to improve the success rate of experiments.

5. Summary

How does isopropanol precipitate DNA? It precipitates mainly by reducing the polarity of the solution so that the DNA molecules no longer dissolve. The isopropanol precipitation method is not only efficient and simple, but also has a wide range of applications and is widely used in DNA extraction and purification. Although there are some challenges in the use process, through the correct operation steps, the success rate of DNA extraction can be maximized to ensure the reliability of the experimental results.