What is DNA? How to extract DNA?

Today I will explain what is DNA and how you can extract it from cell. DNA is the short form of deoxyribonucleic acid. It the hereditary unit of all eukaryotic organisms and most of the prokaryotic ogranisms. DNA is composed of four nucleotides (A- adenine, T- thymine, G- guanine, and C-cytosine) and a backbone made of phospate and dexyribose sugar. In eukaryotic organism Genomic DNA stays inside nucleus. DNA is also present inside mitochondria and plastids organelles. DNA has two different ends 5'end and 3' end. DNA is double helix. Two complimentary strand stay together. Adenine (A) always binds with thymine (T) and Guanine (G) always binds with cytosine (C) by hydrogen bonding. In 1962, James D. Watson and Francis Crick received Nobel prize for describing the structure of DNA in Physiology of Medicine.

Basic principles to extract DNA from cells are:
 Clean raw cells
 Break the cells (lysis) to release DNA into solution
 Destroy membrane, proteins and lipids that may bind and destroy the DNA
 precipitate DNA by using alcohol

Lets extract DNA from onion.

Materials:
blender, salt, shampoo or soap, tea or coffee filter, ethanol of isopropanol, warm water, tooth pick.

Methods:
clean the onion. Cut into pieces, put into blender, add salt and water. Blend for 3-5 seconds. Filter it using tea or coffee filter. Add 2 or 3 spoon of shampoo. Stir gently so that there will be no bubble. Slowly pour ice cold alcohol into the glass. So there will be two layer. Wait for 3-5 minutes. You will see some white DNA at the surface of the top layer. You can collect this layer by tooth pics and put into another tube with fresh water. Within one minute the DNA will be invisible again in the new tube with water.

If you have questions and if you disagree with anything I have written here just mail me.

See also,
http://library.thinkquest.org/19037/dna_extraction.html
http://en.wikipedia.org/wiki/User:Seans_Potato_Business/DNA