Why is alcohol used when extracting DNA from an onion?


What was the purpose of using alcohol in the extraction of DNA?

The role of alcohol in DNA extraction is to precipitate DNA into a visible form. Also, it’s used in DNA washing and storing.

What was the role of alcohol during the onion DNA extraction experiment?

DNA is not soluble in alcohol. When alcohol is added to the mixture, all the components of the mixture, except for DNA, stay in solution while the DNA precipitates out into the alcohol layer. Let the solution sit for 2-3 minutes without disturbing it. It is important not to shake the test tube.

Why is alcohol used in the last step of DNA isolation?

Very simple as DNA is insoluble in alcohols (Ethanol & Isopropanol) we use 100% alcohols for precipitation so we get good amount of DNA. Washing with 70% alcohol is to remove the excess of salts (that might have come along with the extraction buffers) i.e. the excess of salts dissolve in the 30% of water.

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Does alcohol denature DNA?

Since DNA is insoluble in ethanol and isopropanol, the addition of alcohol, followed by centrifugation, will cause the DNA proteins to come out of the solution. … Be careful not to overdry the sample, since this can denature the DNA; just leave the washed pellet on the lab table for a few minutes.

Would you expect a difference between human and onion DNA?

Since the onion (Allium cepa) is a diploid organism having a haploid genome size of 15.9 Gb, it has 4.9x as much DNA as does a human genome (3.2 Gb).

What type of DNA is extracted from an onion?

The students will extract deoxyribonucleic acid (DNA) from tissues of a living organism (the onion) using grocery products.

Why can’t we use room temperature ethanol?

Why can’t we use room temperature ethanol? The colder the ethanol is the greater the amount of DNA that is precipitated. (You could try having some of the students use room temperature ethanol and see if the amount of DNA they can spool is the same or less than that for the groups using the ice-cold ethanol.)

Why 70 alcohol is used for sterilization?

70 % isopropyl alcohol is by far better at killing bacteria and viruses than 90 % isopropyl alcohol. As a disinfectant, the higher the concentration of alcohol, the less effective it is at killing pathogens. … Coagulation of surface proteins proceeds at a slower pace, thereby allowing the alcohol to enter the cell.

Why is 70 ethanol used in DNA isolation?

DNA is washed with 70% ethanol to remove some (or ideally all) of the salt from the pellet. … because precipitation in 100% ethanol cause removal of all water molecule from DNA and Complete Dehydration,which make them not soluble, So we give 70% wash to let it retain some water molecule when make it soluble.

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How do you make 95% alcohol to 75?

To replace 1 liter of 95% alcohol we have to use 1.26 liters of 75% alcohol.

This means that you have 75% of pure alcohol and 25% of water:

  1. 0.75 x 1000 = 750 ml.
  2. This is the amount of pure alcohol.
  3. 0.25 x 1000 = 250 ml.
  4. This is the amount of water.

How do you make 70% ethanol from 95%?

For example, to make 70% ethanol from 95% ethanol, take 70 mL of 95% ethanol and add enough water to bring the volume to 95 mL. You will then have 95 mL of 70% ethanol. This works for any dilution and all that is required is a large enough graduated cylinder.

How do you dilute 500ml 99% isopropyl alcohol to 70?


Dilute by adding 1 part water to 2 parts of this 99% Isopropyl Alcohol.