Extract dna from living cells

Extraction of DNA is never been an extreme task as we think, since we know very well in detail about the arrangement inside the cell and how they behave as we can observe them through different kinds of microscopes. Before going into detail, let me take you through some of the biological chemistry behind the cells from which the living creatures are made up of..!

Simple structure of a cell of animal cell

We already know where the DNA is located in the cell - it is found in the nucleus as shown on the diagram above. So how we can get into the the nucleus is the issue we have right? Therefore let us give a close look into the structure of the cell. In order for us to get what is inside the nucleus, we shall have to get rid from the barriers surrounding the nucleus. As you can see, the only barrier in an animal cell is the cell membrane.
If you study the structure of the cell surface membrane, you will find that it is made up of a bilayer of phospholipids as shown in the diagram below.

Phospholipid bilayer

Usually, the hydrophilic part is known as the head, while the hydrophobic is known as tail. And also within this layers, there are larger protein molecules too as shown in the diagram below.

Let us study the chemical structure of a single phospholipid molecule. The head part is made up of a phosphate containing glycerol and the tail is made of fatty acids. Collectively, this molecule has properties of a lipid.

Now, the most interesting question would be how to break this lipid. We can use a detergent to get rid of this lipid. Usually we use this to get rid of oil in sauce pans, etc.

Any detergent could be used

Now we know how to get rid of the cell surface membrane partially. But yet there are large protein molecules blocking our way..! In fact, we can dissolve the proteins by using some table salt ( NaCl ). These can help us to get rid of the cell surface membrane.

There is another membrane, remaining. That is nuclear membrane. We do not need to worry about this because, even this membrane will be dissolved by the action of the detergent. 

As we have get rid of all the membranes, the DNA should have come out of the nucleus. But yet, we will have to isolate it in a medium. The DNA is in the solution but we cant observe it clearly. For this purpose we use some kind of alcohol ( you also can use ethanol ) to dissolve the DNA molecules. Remember the cold alcohol would be better because, DNA could be more insoluble in the cold environment. The purpose of adding alcohol gently, is really important as the DNA could get dissolved as soon as it is free from nuclear walls. So I recommend if you could add the alcohol as soon as possible. 

At last, you should come across the DNA as thread like structure ( maybe they are the nucleotides ) as shown on the photo as shown below.

Hope you enjoyed the post. If you have any question regarding the post, please leave a comment over here.

What are the applications for this type of experiments?

• Parental testing
• Prenatal tests
• DNA profiling

Resources

• Much more detailed experiment can be found in : http://www.funsci.com/fun3_en/dna/dna.htm
• How to extract dna at home
• http://www.smarterthanthat.com/experiments/dna-madness/
• Video of DNA extraction from strawberries by National Human Genome Research Institute (NHGRI)
• DNA extraction from National Human Genome Research Institute (NHGRI)
• Instructions to extract DNA by www.genome.gov