Does this procedure for extracting DNA from strawberries work?

Does this procedure for extracting DNA from strawberries work?

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I wanted to try out this experiment for extracting DNA from strawberries that can be done at home:

However, while doing a bit of reading, I came across this article:

It states that, "Although these fruits [kiwi fruit, bananas and strawberries] seem to yield copious amounts of DNA, the substance produced is in fact little more than pectin."

Are they right? How could you tell that what you've extracted is actually DNA?

The extraction protocol described in the first article is a standard DNA extraction protocol. I've used variations on this method in the lab (with some refinements) on other types of cells at least hundreds, if not thousands, of times. The "strawberry" experiment is very popular for classroom demonstrations, especially at the middle-school and high-school levels, because it's visually interesting and uses commonly available reagents. While these reagents aren't laboratory-grade, they're more than sufficient for a basic extraction of DNA.

I can't think of a scientific basis for why the author in the second article would claim that the extracted substance is "little more than pectin". Since he didn't provide data, or a reference to any data, it's hard to know what he's basing his conclusion on.

It's definitely possible that the DNA is pulling down a certain amount of cellular proteins during the alcohol precipitation step (the final step). This is why in a lab setting you typically perform a few more steps to "clean up" the DNA and remove any co-precipitating proteins. This would be essential if you plan to do further analysis of the DNA, because protein contaminants can interfere with subsequent analyses, making the data unreliable. One exception would be if you're studying protein-DNA interactions, but that's a separate type of experiment.

I'm assuming this experiment will be done for/by beginner level students, as opposed to a college or graduate level class? If so, then for the purposes of a classroom demonstration, those extra purification steps aren't warranted. It's time-consuming, and it would be very boring to watch… As is the case with most labwork. :-) Even if you perform those additional steps, the purified DNA is often precipitated with alcohol again, and it's visually similar to what you saw in the first alcohol precipitation, just a bit less opaque. Probably not something most students would notice or find interesting.

Either way, it's entirely acurate to say that the strawberry experiment is extracting DNA. You could always explain that the DNA might have cellular proteins binding (or "sticking") to it, and that a few other steps would have to be performed if you wanted to analyze the DNA in a lab setting, because the proteins would interfere with DNA analysis. This would also give beginner-level students an introduction to the fact that DNA and proteins interact with each other.

Hope that helps!

DNA Extraction - Strawberry

Strawberries are octoploid, which means they have eight sets of chromosomes. The procedure for extracting DNA from a strawberry is simple, and the results are usually obvious, it is easy to see the white strands of DNA within the pink solution of strawberry juice.

In this procedure, you will crush a strawberry and add detergent and salt to break down the cell walls to release the DNA within the nucleus. You will then filter the liquid from this crushed strawberry into a beaker, the substance is called the filtrate. The filtrate is then poured into a test tube and a layer of alcohol is poured over the top. The DNA will then precipitate into the alcohol layer in a test tube

  • Extract DNA from a strawberry using household products
  • Identify the role of chemicals in the process of extracting DNA
  • Observe a large sample of DNA

Materials Needed:

  • DNA Extraction Buffer:1000 ml of deionized water, 50 ml of clear dish detergent, 1 teaspoon of salt
  • Strawberry (other fruits also work)
  • Ziploc bag
  • Coffee filters and funnels
  • Test tubes, beakers, or cups to collect filtrate

1. Add a strawberry (or half) to a Ziploc storage.
2. Add 10 ml of the DNA extraction buffer and mash the strawberry and buffer for about one minute.
3. Use a funnel and coffee filters to filter the strawberry juice into a beaker.
4. Transfer the filtrate to a test tube, you should only fill the test tube about halfway full and avoid transferring any foam.
5. Slowly pour or drip cold alcohol over the top of the strawberry mixture. You want a single layer on top of the strawberry mixture.
6. White strands will form in the ethanol layer, use a stirring rod to spool the strands.

Discussion Questions

1. What does DNA from the strawberry look like?

2. Why is it important for scientists to be able to remove DNA from cells?

3. What is the role of detergent, ethanol, and salt in the extraction process?

4. What is the difference between the filtrate and the precipitate?

4. Is there DNA in your food? How do you know? Why are you not harmed (or altered) by ingesting the DNA of another organism?

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DNA Extraction Experiment

DNA In Test Tube (Pict : Richard Newstead)

DNA or Deoxyribo DeoxyriboNucleic DNA stands for deoxyribonucleic acid is a genetic information code molecule that exists in most living organisms. DNA is the material that forms chromosomes and is also the genetic information stored in the bodies of living things. This genetic information in the collection is a collection of commands / commands that are prepared to be able to do certain things.

Although we can use all the DNA sources, but for this experiment it is better to use DNA sources from ingredients such as green beans, spinach leaves, strawberries, chicken livers, and bananas. Do not use DNA from people who live or pets.

1,100 ml of DNA source
2.1 ml table salt, or NaCl
3. 200 ml of cold water
4. Enzymes to change the properties of proteins (eg, meat tenderizer (papaya sap), fresh pineapple juice, or contact lens cleansers)
5. 30 ml dishwashing detergent liquid
6. Alcohol 70-90% or isopropyl alcohol or ethyl alcohol

1. Mixers
2. Blender
3. Sieve
4. Cup or Beaker Glass
5. The test tube
6. Straws or toothpicks

1. Mix all ingredients, 100 ml of DNA source, 1 ml of salt, and 200 ml cold water. then blended with a blender and with a quick stirring of more than 15 seconds, this process aims to obtain a homogeneous concentration of the mixture. After this blasting the cell wall apart, and release the DNA stored in it.

2. Pour the liquid through the filter into another container. The purpose of this process is to remove large solid particles. The liquid is removed and the solid is discarded.

3. Add 30 ml of detergent liquid into the solution. Stir or turn the solution homogeneously. This solution is allowed to react for 5-10 minutes before proceeding to the next step.

4. Add a bit of meat tenderizer or spray pineapple juice or clean lens contact lid for each bottle or tube. Stir gently to combine the enzyme. Stirring hard will damage the DNA and make it harder to see in the container.

5. Tilt each tube and pour the alcohol on either side of glass or plastic to form a layer floating above the liquid. Alcohol is less dense than water, so it will float in the liquid, but we do not want to pour it into the tube because it will mix. If we examine the surface between the alcohol and each sample, you will see the mass of the white thread. This is DNA!

6. Use a wooden or straw skewer to capture and collect DNA from each tube. You can check the DNA using a microscope or magnifying glass or place it in a small container of alcohol to store it.

1. The first step in this experiment is to choose materials that contain lots of DNA. Although we can use DNA from anywhere, the source of high plants in DNA will produce more products at the end of the experiment. The human genome is diploid, which means it contains two copies of each DNA molecule. Many plants contain multiple copies of their genetic material. For example, strawberry octoploid and contains 8 copies of each chromosome.

2. Blending is a process of separation / breakdown of cells so that we can separate DNA from other molecules. Salt and detergent to remove proteins are usually bound by DNA. Detergents also separate the lipids (fat) from the sample. Enzymes used to cut DNA. Why do we want to cut it? The DNA is folded and wrapped around the protein, so it needs to be liberated before it can be isolated.

3. Once we have completed the above steps, the DNA has been successfully separated from other cell constituents, but we still need to get it invisible. This is where the function of alcohol plays an important role. The other molecules in the sample will dissolve in alcohol, but DNA is not. When you pour alcohol (the better cold) into the solution, the DNA molecule settles so we can collect the DNA.

Extracting DNA from Strawberries

Determine which stage of the strawberries would be the most easy to extract DNA from, under-ripe, ripe, or over-ripe.


DNA, or Deoxyribonucleic Acid, is the molecule of life. DNA exists in every single organism, from the smallest virus to the largest mammal, and is the only known molecule that has the ability to replicate itself.

DNA is a long fiber &ndash like a hair &ndash only thinner and longer. It is made from two strands that stick together with a slight twist. The DNA is organized into stretches of genes where proteins attach to coil the DNA into chromosomes, stretches that &ldquoturn a gene on&rdquo and &ldquoturn a gene off&rdquo.

California strawberries, are a genus of plants in the family rosaceae, and the fruit of these plants. There are more than 20 named species and many hybrids and cultivars, but the most common strawberries grown commercially are cultivars of the garden strawberry. Strawberries are also known as a nutritious &ldquosuperfood&rdquo, packed with antioxidants, including Vitamin C. One serving of 8 medium-sized strawberries has only 45 calories, and provides 140% of the US Recommended Daily Allowance (RDA) for Vitamin C, 210 mg of potassium, and almost 3 grams of fiber.

Ripening is the process in fruit that causes them to become more edible. As in humans, plant hormones are chemical compounds that help regulate growth processes. Fruit grows as hormones make its cell walls more elastic and expandable. Other hormones break down chlorophyll, allowing bright, appealing colors to develop. Hormones decrease the acidity of the juice and convert complex carbohydrates in the tissue into sweeter simple sugars.


  1. 3 average sized under-ripe strawberries
  2. 3 average sized ripe strawberries
  3. 3 average sized over-ripe strawberries
  4. ½ Cup of tap water
  5. 2 small, clear plastic cups
  6. 2 measuring cups-1 teaspoon, 1 cup
  7. Paper towels (use for drying your other materials, number may very)
  8. 2 teaspoons of dish detergent
  9. 2 teaspoons of salt
  10. 1 Coffee Filter
  11. 1/3 cup of Rubbing Alcohol
  12. Wooden Popsicle Stick
  13. 1 Plastic Bag

Experimental Procedure:

STEP 1: Mix the DNA Extraction Liquid
  1. Take 1 plastic cup and mix together 2 teaspoons of dish detergent
  2. Then take1 teaspoon of salt in mix in slowly
  3. After take ½ cup of water and mix.
STEP 2: Get the DNA
  1. Take 1 strawberry and insert it into your plastic bag
  2. Using your hand, mash up the strawberry until there is no big chunks
  3. Add 2 tablespoons of the DNA extraction liquid
  4. Swirl gently using a wooden popsicle stick for at least one minutes and then let it sit
STEP 3: Separate the Fluids from the Solids
  1. Take coffee filter and cover it over an unused plastic cup
  2. Pour the mix of strawberry and let it filter for 30 seconds or until the fluid has stopped dripping
STEP 4: Extract the DNA
  1. Next, pour down the side of the cup an equal amount of cold rubbing alcohol as there is strawberry liquid. Do not mix or stir.
  2. Within a few seconds, watch for the development of a white cloudy substance (DNA) in the top layer above the strawberry layer
  3. Tilt the cup and pick up the DNA using a wooden popsicle stick and put it into a measuring cup.
STEP 5: Measure the Amount of Extractable DNA
STEP 6: Repeat Process with Other Types of Strawberries
  1. Rinse all plastic cups and other materials thoroughly with water and dry all materials using paper towels to avoid contamination
  2. Repeat this process with the other types of strawberries to determine which one is the most extractable to get DNA.

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DNA: background information

What does DNA stand for?

DNA stands for deoxyribonucleic acid.

DNA is a long molecule in the shape of a double helix - two spirals twisting around each other. These spirals are the backbone of the DNA, and are made up of sugars and phosphates. The spirals are connected by chemicals known as bases, which stretch between the spirals like the rungs of a ladder. DNA has four types of bases: adenine (A), thymine (T), guanine (G) and cytosine (C). A and T always join together, as do G and C.

What does DNA do?

Our genes are made up of DNA, and DNA contains our unique genetic code.
Like a recipe book or instructions for lego , DNA holds the instructions for making all our proteins, which do all the jobs in our bodies.

Genes in common

You don’t look much like a fly or a worm. But, believe it or not, you share genes with both of them and with every other living thing. Scientists study the genes in bacteria, zebrafish and other living things to learn more about humans.

How much DNA do you share with these living things?

Why do we use the dishwashing liquid?

The dishwashing liquid bursts open the cells of the strawberries, releasing the DNA.

Why do we use the salt?

It ensures that the proteins in the cell are kept separate from the DNA.

What does the alcohol do?

When molecules are insoluble (unable to be dissolved), they clump together and become visible. DNA is not soluble in alcohol therefore, it makes the DNA strands clump together and become visible to the naked eye.

Onion DNA Extraction Experiment

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 Onion (alium cepa)

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

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

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.

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.

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.

13. The formed DNA can be taken with a tooth or pipette or what stem of a crooked stirrer can take the DNA
  • A series of lab exercises giving instructions for the extraction of DNA from several different starting materials. The exercise is designed for the 6-12 grade level.

The following resources were originally accessed through the BioSciEd Net (BEN) digital resources collection, which is the National Science Digital Library (NSDL) Pathway for biological sciences education. For more teaching resources, please visit BEN to use their searchable database. BEN is free to use, but requires registration.

    - This lab, from AccessExcellence enables students to work with DNA concretely by easily isolating chromosomal DNA using the same basic tools and methods that scientists use. - this Science NetLinks website provides lesson plans that develop understanding of DNA by modeling the process of DNA extraction.
  • [link 'DNA the Easy Way (and Gram Stain Without the Mess)'] - This resource, by the American Phytopathological Society, is a short laboratory exercise that teaches students the procedures of DNA isolation from bacterial cells. In addition, students learn how to determine the Gram-stain reaction of bacterial isolates. : This Access Excellence resource provides a laboratory activity where students use DNA fingerprinting analysis to determine the perpetrator of a fictitious crime. - This resource requires you to log in to BEN to view (which requires a subscription to BEN, which is free). This PDF document offers a detailed manual of protocols and instructional information for carrying out an undergraduate laboratory exercise in molecular biology and cenetics, in which students use polymerase chain reaction to create DNA fingerprints from their own hair. It includes student outlines, instructor's notes, and suggested questions for laboratory reports.



Material on this page is offered under a Creative Commons license unless otherwise noted below.

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A well-stocked pantry allows you to conduct countless simple but fascinating science experiments and activities all month long!


  • Coffee filters
  • Pipette
  • Test tube
  • Strawberries
  • Dish Soap
  • Salt
  • Plastic Zipper Baggies
  • Rubbing Alcohol


Yields of DNA obtained from buccal swabs and urine are highly altered depending on the swab or the urine type, the individual being swabbed, the swabbing technique, and the number of cells captured on the swab and in the urine. 6 , 11 The expected yield using this protocol is 60� ng/μl/swab and for urine, 25� ng/μl/15 ml collection ( Table 1 ), which is, at least, a factor of two higher when compared with the conventional methods. The yield and purity of isolated DNA are also dependent on the researchers' handling procedures. A decrease in DNA quality and quantity was observed when the material was not placed immediately in cell lysis buffer for further processing. The degradation of DNA bands was observed in buccal swabs and urine specimen processed with the time delay, whereas degradation in blood and hair sample is not observed, probably as a result of the nature of the sample and the extent of nuclease enzyme concentration in the sample before digestion. Although there was a certain degree of DNA degradation in samples stored under cold temperature condition for 3 days, the present study did not exhibit any significant difference between the extracted DNA PCR amplification products from the buccal cells immediately after the sample collection or from the buccal cells frozen 3 days at �ଌ. Moreover, 1 week of storage, as refrigerated at 4ଌ or frozen at �ଌ, also did not affect the yield of the extracted DNA or PCR amplification of DNA. In the case of hair and blood samples, a high quality of DNA can be obtained for later use, even after storage of the hair sample in ethanol for more than 2 months and the blood sample in the EDTA-coated vial for more than 4 months at �ଌ.

In general, for DNA-typing studies, fresh whole blood or blood-stained material is the primary source of an individual's DNA 𠇏ingerprint” and is used as a standard for comparison. The findings presented here allowed us to demonstrate use of the buccal swabs and urine as alternative sources for extraction of DNA. However, there is a marked difference between male and female urine samples regarding the quantity of DNA available as in most cases, there is no information regarding the gender when the urine is collected from a crime scene, 10 it should always be collected from the largest urine stains that are available. Large volumes of saliva and urine can be collected in a noninvasive manner without any pain. In fact, a buccal swabbing and the urine were easily obtained with minimum fuss for a detailed analysis, even from an infant. 14 We can also amplify viral and bacterial genes from the DNA of urine and buccal swabs for the study of a presence or absence of any pathogens using the reported PCR assay.

The isolated DNA from all samples has generated PCR products of a similar base-pair size of the target mitochondrial gene. However, in the case of restriction digestion, hair and blood PCR products produced excellent digested products. This may be a result of the presence of good concentration of PCR amplification products and the absence of any impurity in the PCR sample, rather than urine and buccal swab samples that were not digested properly by the restriction enzyme. Hence, we can use hair samples instead of blood samples for the PCR-RFLP-based molecular analysis.

There is a possibility for low levels of contaminants that may be present in the DNA isolated from the serum or plasma that are much less abundant rather than those that exist in urine and buccal swab specimens. 15 In these techniques, there are fewer amounts of contaminants, so the probability of interference of the contaminants during the PCR process is very low.

Harty et al. 16 have reported that PCR amplification was successful after a long storage of samples, even though the storage has reduced the yield of DNA. In the present study, the isolated DNA from all samples stored as frozen at �ଌ was suitable for later use. The DNA extracted from the urine sample that was stored for over 1 month frozen at �ଌ performed as good as a fresh urine sample. Although the DNA in the urine specimen seems to degrade over a period of time, the urine sample, stored up to 3 months frozen at �ଌ, may still be used for PCR amplification. Isolated DNA from the hair and the blood is very good on the basis of the stability of DNA for storage as frozen at �ଌ for further analysis.


The successful sample collection and the extraction of genomic DNA from buccal swabs, urine, and hair are noninvasive and reliable alternatives to the prickly invasive blood sampling, both for subjects and sample collectors. 17 – 20 We have demonstrated here a simple and novel method of the sample collection and DNA extraction, which is cost-effective, easy, and rapid, providing a sufficient quantity and quality of DNA for PCR-RFLP-based analysis. Comparison of the extraction procedures shows that the simple phenol-chloroform method is the most suitable for DNA extraction from buccal swab, urine, hair, and blood samples. Under appropriate storage conditions, DNA isolated from buccal cells, urine, and hair can be successfully used to perform PCR-based assays. The DTT, high-salt, anionic detergent solution mtDNA extraction method developed in this study represents a rapid and simple protocol that excels the mtDNA amplification success rate of the standard glass-grinding/organic solvent extraction techniques currently used by many forensic laboratories. The relatively lesser number of steps used in this method facilitates shorter time duration and in addition, results in a significantly reduced probability of contamination with a minimal sample loss. The DTT chemical digestion method uses reagents, supplies, and equipment readily available in any basic laboratory. Its ease will help in mtDNA analyses in those laboratories that have yet to undertake forensic mtDNA testing, as well as a population-based study using hair samples. However, important questions still remain to be explored regarding the yield and quality of human DNA that can be obtained from different DNA extraction methods.