DNA Extraction!

Why would we want to isolate an organisms DNA? List 3 reasons

How do we get DNA out of the cell? The DNA is stored in the nucleus so we need to break the cell membrane and the nuclear membrane. We also need to separate it from all the other “stuff” inside of a cell

Step 1: get cells! Get some water from the fountain and start swishing! What kind of cells are you collecting? Prokaryotic of eukaryotic? Plant or animal? Do you know the specific cell type?

Step 2: Soap! Detergent contains sodium laurel sulfate, which cleans dishes by removing fats and proteins. It acts the same way in the DNA extraction protocol, pulling apart the fats (lipids) and proteins that make up the membranes surrounding the cell and nucleus. Once these membranes are broken apart, the DNA is released from the cell. Soap molecules and grease molecules are made of two parts: Heads, which like water = hydrophillic Tails, which hate water = hydrophobic Both soap and grease molecules organize themselves in bubbles (spheres) with heads outside to face the water and tails inside to hide from the water

Step 3:Meat tenderizer?!? Proteases help to break down the enzymes and proteins that would otherwise attack the DNA. Why would you have DNA attacking proteins in your cell?

Step 4:Why the salt water? You are using NaCl to help separate the proteins from the DNA, it also helps keep the proteins in solution because most proteins are polar and will be attracted to the salt.

Last step: Alcohol The DNA released from the cell nucleus is dissolved in the cell suspension and cannot be seen. DNA precipitates out of solution in alcohol, where it can be seen. Besides allowing us to see the DNA, the alcohol separates the DNA from the other cell components, which are left behind in the water solution DNA is insoluble in alcohol.