Onion DNA Extraction Experiment

Preface
In this experiment, onions are used, this is because the onion has a low starch content, which allows the DNA to be clearly visible. Salt protects the negative end of the DNA phosphate, allowing the tip to come closer so that DNA can precipitate from a cold alcohol solution. Detergents cause cell membranes to break down by dissolving lipids and proteins from cells and disrupting bonds that hold the cell membranes together. Detergents then form complexes with lipids and proteins, causing them to precipitate the solution.

Equipment and materials
Ethanol 95%.
Thermometer
Plate.
Measuring cup.
1000 mL bekaer glass.
Funnel.
Filter
Test tube
Freezer
Hot plate with bath
Ice Cube.
Spoon
Dishwashing soap or shampoo
Table salt, either iodized or not iodized
Distilled water
Great onions
Blender and knife to cut onion.
Timer or clock

Experiment procedure
1. Prepare two water baths, one for temperature 55-60 ° C and another fill with ice cubes and water, about 4 ° C.

2. In 250 mL beaker glass (or 1 cup), add 10 milliliters (ml) (1 tablespoon) dishwashing liquid detergent or shampoo and one 1/4 teaspoon (1.5 gram) table salt.

3. Add the distilled water to the beaker to the final volume of 100 mL. Dissolve the salt by stirring slowly to avoid foaming.

4. Cut one large onion with a knife then blender and put in 1000 ml beaker glass

5. Pour 100 ml of solution in step 3 into the onion chopped onions that have been in the blender. Liquid detergents cause cell membranes to break down and dissolve lipids and proteins from cells by damaging the bonds that bind the cell membranes together. Detergents serve to precipitate lipids and proteins from the solution. Table salt (NaCl) allows nucleic acids to precipitate from an ethanol solution because it protects the negative end of phosphate from DNA, causing the DNA strand to come closer together and fused.

Pour 100 ml of solution in step 3 into the onion chopped onions that have been in the blender. Liquid detergents cause cell membranes to break down and dissolve lipids and proteins from cells by damaging the bonds that bind the cell membranes together. Detergents serve to precipitate lipids and proteins from the solution. Table salt (NaCl) allows nucleic acids to precipitate from an ethanol solution because it protects the negative end of phosphate from DNA, causing the DNA strand to come closer together and fused.

6. Input the 1000 mL glass of the DNA solution in a hot water bath at 55-60 ° C, as shown in the figure below, for 10-12 minutes.

7. The heat treatment softens the phospholipids in the cell membrane and denatures the DNAse enzyme, which if present would cut the DNA into small fragments so that it can not be taken.

8. Cooling the mixture in a water ice bath, about 4 ° C, as shown in the picture, below, for 5 minutes. In this process, press the onion DNA mixture against the side of the glass with the spoon back. This step slows DNA damage.

Cool the mixture in a water ice bath, about 4 ° C, as shown in the picture, below, for 5 minutes. In this process, press the onion DNA mixture against the side of the glass with the spoon back. This step slows DNA damage.

9. Strain the mixture with a coffee or tea strainer. When the process of filtering the onion mixture is attempted to keep the foam from entering the filtrate.

Strain the mixture with a coffee or tea strainer. When the process of filtering the onion mixture is attempted to keep the foam from entering the filtrate.

10. Remove the onion DNA solution into the reaction tube approximately 5 ml. Solutions can be stored in the refrigerator for about a day before use in the following steps.

11. Take a cold 95% ethanol solution from the freezer and add it to the test tube to make the ethanol layer above about 1 centimeter (cm). For best results, ethanol should be as cold as possible. Ethanol can be added to the solution

12. The DNA does not dissolve in ethanol. When ethanol is added to the mixture, all components of the mixture, except DNA, stay in the solution while the DNA settles out into the ethanol layer. The solution is allowed to stand for 2-3 minutes then white DNA will settle into the ethanol layer.