Genetics:

Experiment Instructions (Demonstration)

MATERIALS NEEDED (DNA Isolation)

Salt

Distilled water ,not spring, mineral or tap water; often found in automotive section)

Straw

Coffee Filter Bowl with ice Blender Onion

Baking Soda

Coffee stirrer (get one for free at any fast food place) Chilled rubbing alcohol (or liquid lioiirl srmiti er ) Food Coloring (any color)

DNA ISOLATION

**You u ill be quizzed on the purpose of each step. Please pay attention to the information below! **

When isolating DNA. four key iliinp•s need to occur. Firstly. the onion cells must be broken apai’t Groin each other by blending. This also breaks the cell walls in many

places. Secondly. the plasma membrane and nuclear envelope must be removed. Since they are made of lipids, the dis1iwas1iinq• deierp•ent can "v’as1i” them an ay. Thirdly, the proteins wrapping the DNA need to be deiiatured. (Remember that deiianiring a protein is changing iis shape to make ii inactis e. ) The salt in the buffer will cause the proieins to denatui’e

some, separatin_• iheni from the DNA. Finally, the water-soluble DNA iniist be forced out of solution. Rubbing alcohol pulls on the DBA av’ay from the u’ater. preventing the DNA Groin staying dissolved. Even iliouq•1i the alcohol pulls on ihe DNA. ii won't actually dissolve the DNA either. lean inc DNA trapped between the v ater and the alcohol.

1. Make a Biit’1“er solution by pourin_• 4 oz. of Distilled V’ater into a clean glass. Add F\ teaspoon of Salt. Add 1 teaspoon of Baking Soda. Add 1 teaspoon o1“ liquid detergeiii.        Siii‘ all in_•redients well then chill iii a bou’1 of ice water until i1iorou%ilv chilled.

2. Finelv chop onion (or oilier food stuff and add to a blender or food processor. Add a small amount of aiei’ to the onion then pulse in 10 sec. bursi to break up the onion cells.

3. Place a teaspoon of iTiixed vegetable inusli into a clean glass then add ? teaspoons of the chilled buffer solution (front step 1). Stir vigorously for‘ at least 2 minutes.

4. Strain material from s 3 t1uoup•1i a coff’ee filier to reinos e most of the plant refiise.

5. From the matei’ia1 filtered (hltrate). pour’ off the solid floating on the surface.

6. To extract the DNA fi’oin the solution. dip a drinkin_• straw into the chilled rubbing alcohol ilien place the pad of your finger on the oilier end of the drinking sti’aw which will keep the alcohol in the straw until you transfer it to the solution in the glass.

7. Release ihe alcohol in the sii’aw very slowly by allo ing it to trickle down the side o1“ the glass containing the DNA soluiion. The alcohol being less dense than the buffer will float on top.

8. Where the two layers ilieet. you u’ill be able to see a q•elatinous sliid•e                                                                                           hich will be the DNA. Gently insert the stin‘ing stick tlirougli the layer of alcohol (barely peiietratiiie the alcohol bin not the buffer solution) to pick up the sludee.

9. Gingerly t ir1 the stiri‘ing stick back and torth with ihe tip of the stirriiie stick suspended trust below the boundary benveen the alcohol and buffer solution.

Alter a minute of twirliiie. pull the stirrings stick with the DNA attached up t1irou_•1i alcohol. The DNA will will appear as a viscous clear sludge clinging to the stirring stick.

You have now successfully extracted DNA. Paste a picture of your DNA sludge into the worksheet (or add it to the Assignment Box directly) and answer questions about what each clieiliical did during this process!

GENETICS SIMLTLATION

You will be testing the *.aw of Segregation using eye color and then aeain using the presence of a tail. You will then test the Law of Independent Assortment using both eye color and tail at the same time.

Experiment #1 - Segregation of Eye Color(Black vs lVhite)

1. Open the next two items in the module; a link to the Hzreditv I simulator and a worksheet. Return here for further instructions.

2. Tiiese little creatures in the simulation are called Flugals. Female Fliigals ai‘e brown arid smooth. Male Flugals are red and hairy. These differences are just there to distract you! The real experiment is about eve color.

3. Choose a mating pair of Flugals where one has white eyes and the other has black. It will also help if both have tails or both are missing tails. It doesn’t matter which, we just want to be able to ignore the tail and focus on the eyes.

4. The Flugals running around the screen now are the offspring from this first cross (F1). Thankfully, you don’t have to count them. because the number of each phenotype is shown at the top. You now have the information you need to answer the first three questioiis of Experiment #1. Go answer them now. including the hypothesis for what you think the ne i generation will look like.

5. Now click the pair of Flugals waiting at the bottom of the screen where it says “Click to select F1 cross.” This will create the F2 veneration.

6. Compare your data to your hypothesis. Were you correct? Select “Click to Return to reset the simulator.

Experiment #2 - Segregation of Tail ainl Tailless

Repeat the experiment above, but tliis time select parents with the same eye color. but different tails. Use the F1 results to determine which phenotype is dominant and the F2