1. The salt contributes positively charged atoms that neutralise the normal negative charge of DNA. Salt is used at a high molar concentration due to the fact that it precipitates all of the proteins out. Deoxyribonucleic acid is indissoluble in low molar salt solutions but soluble in low molar salt solutions therefore maintaining the Deoxyribonucleic acid in solution. 2. intermixing the onion will homogenise the mixture and it helps with the dislocation of the cell walls. Blending saves one the clip and attempt of utilizing a motar and stamp. nevertheless it may interrupt a batch of the DNA which is non favorable as one needs a batch of DNA for the extraction. 3. The enzymes in the soap are used to interrupt down the lipoid ( fat ) molecules of the cell’s atomic membranes let go ofing the contents of the cell crucially including the Deoxyribonucleic acid. These enzymes in the soap are what interrupt down lubricating oil while rinsing dishes.

4. The Deoxyribonucleic acid does non fade out in this intoxicant but instead pushes up through and out of the solution or precipitates. It is less heavy than H2O or cell trash which is what settles to the underside of the glass so it floats up into the intoxicant bed. where you see it as a bigheaded. string-like substance. with little bubbles formed on it. 5. Because protein is stored in them for the nutrition of the new workss. 6. It is excessively little to be seen with the bare oculus. What you extracted is 1000000s of strands of DNA. In add-on to that. whilst the substance was heated. the Deoxyribonucleic acid got denaturized which consequences in it looking more like a ladder than a spiral. 7. Most of the DNA extracted during this proccess comes from the karyon of the cell.


The intent of this experiment is to pull out DNA from a assortment of cells ( Onion cells in peculiar ) and see DNA molecules. This will demo that. contrary to popular sentiment. Deoxyribonucleic acid is non merely found in blood cells. but in a assortment of tissues. Prior cognition should include the fact that cell membranes are beds of lipoids. or fat molecules. that Deoxyribonucleic acid is found in the karyon of a cell. and that enzymes speed up chemical reactions. Hypothesis: Deoxyribonucleic acid is present in the cells of all life beings.

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1. Fix two H2O baths – one at 60°C and another filled with ice and H2O. around 4°C. For the hot H2O bath. a big metal pot can be used along with a thermometer with an appropriate temperature scope. For the ice bath. a blending bowl filled with ice and H2O plants good. 2. For each onion. do a solution consisting of 10 milliliter of liquid dishwashing detergent and 1. 5 g of table salt. Put in a 250 milliliter beaker and emulsify. 3. Add distilled H2O to do a concluding volume of 100 milliliter. Dissolve the salt by stirring easy to avoid foaming. 4. Coarsely chop one big onion with a nutrient processor or liquidizer and set into a 1000 milliliter blending bowl. For best consequences. do non chop the onion excessively finely. The size of the pieces should be like those used in doing spaghetti. It is better to hold the pieces excessively big than excessively little.

5. Cover chopped onion with the 100 milliliter of solution from measure 2. The liquid detergent causes the cell membrane to interrupt down and dissolves the lipoids and proteins of the cell by interrupting the bonds that hold the cell membrane together. The detergent causes lipoids and proteins to precipitate out of the solution. Salt enables nucleic acids to precipitate out of an intoxicant solution because it shields the negative phosphate terminal of DNA. doing the Deoxyribonucleic acid strands to come closer together and blend. 6. Put the measurement cup in a hot H2O bath at 60°C for 10-12 proceedingss. During this clip. press the shredded onion mixture against the side of the mensurating cup with the dorsum of the spoon. ( Do non maintain the mixture in the hot H2O bath for more than 15 proceedingss because the DNA will get down to interrupt down. ) If utilizing a big metal pot for H2O bath. take the pot from the range before puting the onion-containing measurement cup inside—the process is safer if the pot is off the burner. Continue to supervise temperature of H2O bath and do accommodations as needed.

7. The heat intervention softens the phospholipids in the cell membrane and denatures the DNAse enzymes which. if present. would cut the DNA into little fragments so that it could non be extracted. 8. Cool the mixture in an ice H2O bath for 5 proceedingss. During this clip. press the shredded onion mixture against the side of the mensurating cup with the dorsum of the spoon. This measure slows the dislocation of DNA. 9. Filter the mixture through a # 6 java filter or four beds of cheese fabric placed in a strainer over a 4-cup measurement cup. When you filter the onion mixture. seek to maintain the froth from acquiring into the filtrate. It sometimes filters easy. so you might desire to set the whole set up in the icebox and allow it filtrate nightlong. 10. Distribute the onion solution into a trial tubing. The trial tubing should incorporate about 1 teaspoon of solution or be about 1/3 full. For most unvarying consequences among test tubings. stir the solution often when distributing it into the tubing. There is non an advantage to distributing more than one teaspoon of solution into a trial tubing. The solution can be stored in a icebox for about a twenty-four hours before it is used for the research lab exercising. When the solution is removed from the icebox. it should be gently assorted before the trial tubings are filled.

11. Add cold intoxicant to the trial tubing to make an intoxicant bed on top of approximately 1 centimeter. For best consequences. the intoxicant should be every bit cold as possible. The intoxicant can be added to the solution in at least three ways: ( a ) Fill a Pasteur pipette with intoxicant. set it to bottom of the trial tubing. and let go of the intoxicant. ( B ) Or. set about 1 centimeter of intoxicant into the underside of a trial tubing and add the onion solution. ( degree Celsius ) Or. easy pour the intoxicant down the interior of the trial tubing with a Pasteur pipette or medical specialty dropper. Deoxyribonucleic acid is non soluble in intoxicant. When intoxicant is added to the mixture. all the constituents of the mixture. except for DNA. stay in solution while the DNA precipitates out into the intoxicant bed. 1

2. Let the solution sit for 2-3 proceedingss without upseting it. It is of import NOT to agitate the trial tubing. You can watch the white DNA precipitate out into the intoxicant bed. When good consequences are obtained. there will be adequate DNA to spool on to a glass rod. a Pasteur pipette that has been heated at the tip to organize a hook. or similar device. A wooden skewer or nut choice ( little metal rod with curving tip ) may besides work good for spooling DNA if Pasteur pipette is unavailable. Deoxyribonucleic acid has the visual aspect of white mucous secretion.


With these findings we can reason that Deoxyribonucleic acid is present and can be found in the cells of all life beings and non merely in those of the human organic structure.


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