Cooling the mixture is to prevent the DNA from being degraded by the heating.

Temperature has a significant effect on the amount of DNA that can be extracted: the lower the temperature, the greater the yield of DNA. Hence, whenever possible, specimens should be kept at cold temperatures, preferably frozen.

Cooling decreases the rate of chemical reactions, slowing the action of the enzymes before they destroy the DNA. 8) Carefully pour 10 ml ice-cold ethanol into test tube to form a separate layer on top.

Ethanol also makes the DNA less soluble for another reason. Since the ethanol molecules can form interactions called hydrogen bonds with water molecules, they decrease the number of water molecules available to hydrate the DNA.

Once the genomic DNA is bound to the silica membrane, the nucleic acid is washed with a salt/ethanol solution. These washes remove contaminating proteins, lipopolysaccharides and small RNAs to increase purity while keeping the DNA bound to the silica membrane column.

“DNA precipitation is a process in which the nucleic acid is precipitated using alcohol and salt. DNA precipitation is an important step in the DNA extraction protocols, we can say especially, for traditional DNA extraction protocols.

The most commonly used procedures are: Ethanol precipitation usually by ice-cold ethanol or isopropanol. Since DNA is insoluble in these alcohols, it will aggregate together, giving a pellet upon centrifugation. Precipitation of DNA is improved by increasing of ionic strength, usually by adding sodium acetate.

FAQ

1. Add 1/10 volume of 3 M Na-Acetate pH 5.2, and 2 to 2.5 volumes of ice-cold 100% ethanol to the DNA sample.
2. Mix, and store at -20°C for at least 1 hour to precipitate the DNA.
3. Recover the precipitated DNA by centrifugation at full speed in a microcentrifuge for 15-20 minutes.

Ethanol precipitation is a commonly used technique for concentrating and de-salting nucleic acid (DNA or RNA) preparations in an aqueous solution. After precipitation, the nucleic acids can then be separated from the rest of the solution by centrifugation. The pellet is then washed in cold 70% ethanol.

Your DNA’s sugar phosphate backbone is charged. By adding salt, we help neutralize the DNA charge and make the molecule less hydrophilic, meaning it becomes less soluble in water. The salt also helps to remove proteins that are bound to the DNA and to keep the proteins dissolved in the water.

These molecules are also polar because of the negatively charged phosphate group (PO3-) along the sugar-phosophate backbone. Because of this, DNA and RNA can easily dissolve in water.

Use double distilled water (volume that you need) , make sure you don’t dissolve in very less . Keep the DNA sample at 60 degree dry bath for about an hour. I usually do this but i do not know the exact concentration that i took. so you can try this taking less amount of DNA so that your stock is not lost.

DNA can be extracted from anything living. You could also try this experiment with strawberries or bananas. Make sure you remove the fruit skins as they are mostly dead and don’t contain DNA. The kiwi needs to be broken up so the extraction solution can get to the cells.