Bell Work: (Do in your head, not on paper) Which of the following things has DNA? –Strawberry - a tree branch - A zebra –Grass - a hydra –Water - air While you are thinking…. Clear off your table COMPLETELY Put your name on your lab handout Show me you are ready to start the lab You will be working with your seat partner (NOOO!!!)

“DNA is inside of every living or once living thing.” Are these things living or once living? ThingLiving (or once was living)? strawberryYes – so it has DNA grassYes – so it has DNA waterNo – so no DNA a branchYes – so it has DNA hydraYes – so it has DNA airNo – so no DNA zebraYes – so it has DNA

Where is it found? What is it for? Is all DNA the same? The nucleus of all cells of every living or once living organism. (in the chromosomes!) Approximately 99.9% of our DNA is the same (this determines how our bodies are made and how our organs/systems work). The other 0.1% is the stuff that makes us unique (although strangely enough those differences are what we notice most). It contains the genetic information for all your traits – instructions for MAKING PROTEINS! The proteins that your DNA codes for determines how your body works and your physical traits. What is DNA? A very long molecule, with the shape of a double-helix.

DNA Extraction To diagnose a disease or genetic disorder To analyze forensic evidence To study genes and traits To take a gene from one organism and put it in another (Genetic Engineering) Why do it? to remove or separate

cell DNA nucleus

Materials: Each team needs: 1 test tube & test tube rack 1 graduated cylinder 1 zip-loc baggie 1 strawberry 1 funnel 1 glass rod 1 piece of gauze 2 clean paper towels Safety goggles Class will share: extraction buffer (water, salt, detergent) rubbing alcohol

In case you want to do this at home… PROCEDURE To make the extraction buffer… 100 ml of water 6 ml dishwashing detergent (like palmolive) 1 tsp of salt CHILL the extraction buffer and the rubbing alcohol.

Get a strawberry from your teacher and put it directly into your baggie. 1 Seal your zip-loc baggie. You want to have very little air in the baggie. 2 Squish the strawberry CAREFULLY for 2 minutes. You want to make total strawberry mush, with no large chunks. 3

strawberry plant cells

strawberry plant cells extraction buffer = salty, soapy water We need to now break open the cell membrane and the nucleus to get the DNA out! How? The extraction buffer!

Why detergent? Each plant cell has a cell membrane. DNA in the nucleus is protected by a nuclear membrane. We need to break both membranes to get the DNA out – detergent does the job.

Why detergent? (continued) Detergent breaks up fat (grease) molecules (That’s how it gets stuff clean in your kitchen!) Cell membranes are a double layer of PROTEINS and LIPIDS (fats) Detergent breaks apart the membranes so the DNA can get loose in the solution. CELL MEMBRANE (protein & lipid bi-layer)

Have one partner come and get 10 mL of the cold extraction buffer, using the graduated cylinder. 4 Open the baggie and pour the extraction buffer into the strawberry mush, then seal the baggie again, with very little air. 5 Mush the strawberry cells and the extraction buffer for one minute. 6

Put your test tube in the rack, put the funnel in the test tube, and line the funnel with gauze. 7 Pour your strawberry cell mixture into the funnel lined with gauze. 8 Observe what happens as the strawberry cell mixture sits in the funnel. Your goal is to fill your test tube about 1/8 full of cell mixture. 9

1.Throw baggie away. 2.Make sure you have a clean and dry piece of paper towel. 3.Throw gauze away. 4.Place dirty graduated cylinder on the piece of paper towel. 5.Place the dirty funnel on the piece of paper towel. Halfway clean up…

Listen and then watch the teacher demonstration. YOUR GOAL: to add the cold rubbing alcohol so that it DOES NOT mix into the strawberry cells, but just sits on top of the mixture.

CAREFULLY tilt your test tube to a 45 degree angle. 10 VERY SLOWLY squirt the rubbing alcohol along the INSIDE WALL of your test tube, using the technique demonstrated by the teacher. Keep adding until the test tube is LESS than ½ full. 11 Let the test tube sit undisturbed for 2-3 minutes – observe as you wait. 12 Work on PAGE 24 as you wait for your DNA to precipitate.

What’s that stringy stuff? The long stringy stuff is clumps of DNA! Most of the cell parts sink, but the salty dissolved DNA floats near the top. When the salty DNA comes into contact with the alcohol, it forms a precipitate (it becomes NOT-dissolved – and forms into clumps)

DNA

Clean up! 1.Rinse test tube very well 2.Rinse graduated cylinder very well 3.Put (1) & (2) on rack to dry 4.Throw out baggy & gauze (if you didn’t already) 5.Clean glass stirring rod very well; put in bin on table 6.Clean funnel, dry it, and put in bin 7.Clean up any spills; dry table top, wash hands LAB PACK DUE ON MONDAY!