how did the ingredients of a buffer solution assisted in the extraction of DNA?

Question

How did the ingredients of a buffer solution assisted in the extraction of DNA?The experiments purrpose was to extract DNA from a banana. The banana was squished until it was all mushy. Then it was mixed with a buffer solution that contained shampoo,baking soda,salt,and distilled water. I know the shampoo dissolves the lipids and proteins of the cell. During this process the cell membrane is being broken down and the bonds that hold the cell membrane together are filtered out. The baking soda in the buffer solution regulated the pH level of the substance.But can you please help me with the other 2-salt and distilled water. Thanks in advance=)

Answer 1

The distilled water is what holds the solution, and the salt in solution helps to separate the DNA in solution. You should get what we called a "DNA Cloud." The salt is a positive ion, and DNA is negatively charged. The salt neutralizes the DNA after it is freed from the cell membranes, so the DNA molecules aggregate with one another. When you add ethanol(which I assume is what you used), the DNA is forced to clump together at the water/ethanol interface because of the salt. The salt is basically what allows you to collect the DNA.

Gatorade, which is a salt solution, and any soap also work. We collected our own DNA by swishing Gatorade in our mouths, spiting it out, and then mixing in dish soap. You can get quite a bit of DNA this way. The salt in this solution worked both as an abrasive to get cells from our mouths and to clump the DNA together.
I've also done this lab with kiwi DNA. It's very similar to your banana lab, as well as the lab I did.
http://www.exploratorium.edu/ti/human_body/dna.html

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Answer 2

This seems such as you are attempting to chop up plasmid DNA by using affinity chromatography. The plasmid DNA is blended with proteins and different cellular contents. once you pour the mixture during the column containing binding answer, the plasmid DNA will stick to the binding answer and the rest will circulate out of the column. To get the plasmid DNA out, you will pour the elution buffer during the column. The DNA will stick to the buffer (rather of the binding answer) and circulate out of the column. Your end product would be plasmid DNA mixed with elution buffer. The binding answer will incorporate ligands that the plasmid DNA can bind to reversibly. The elution buffer will bind to the plasmid DNA extra strongly, yet nonetheless reversibly.