dna extraction experiment banana

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How to Extract DNA From a Banana

It’s easy to extract DNA from bananas, strawberries, or other polyploid plants. Human cells are diploid, which means each cell nucleus contains two copies of each chromosome (one from each parent). Polyploid cells contain multiple copies of chromosomes, so there is more DNA to collect.

Here is a simple DNA extraction method you can do at home using common, safe materials.

DNA extraction is not complicated. You only need a few basic ingredients.

• Banana (or strawberries or human cheek cells )
• Distilled water
• Dishwashing liquid
• Rubbing alcohol
• Plastic bag OR blender or smoothie maker
• Coffee filter or paper towel
• Toothpick, wooden skewer, or glass rod
• Distilled water is better than tap water because it has a neutral pH and is free of impurities. But, if you don’t have distilled water, tap water usually works fine.
• Ideally, use a translucent dishwashing liquid (not one that looks cloudy or pearlescent). Shampoo containing sodium lauryl sulfate works too. Just make sure it’s not a conditioning shampoo.
• Use regular table salt (NaCl).
• Either isopropyl alcohol or ethanol work for this project. Choose rubbing alcohol (isopropyl alcohol) with a high alcohol content. For the best results, choose 91%, 95%, or 99% (not 60% to 75%). Alternatively, use denatured alcohol (ethanol). Store the alcohol in the freezer to chill it before use.

You can perform the project in a plastic bag or you can use a test tube or small glass. There is nothing dangerous in this project (but don’t drink it), so you can use kitchen glassware safely and then wash it before using it with food. You’ll get a better extraction using a blender or smoothie maker rather than a plastic bag, but a banana has enough DNA that the plastic bag method works fine.

• Either blend 1 banana and 1/2 cup water or else place the ingredients in a plastic bag and squish them well.
• In a small cup, mix 1 teaspoon of dishwashing liquid, 1/4 teaspoon salt, and 2 tablespoons water. Stir gently to dissolve the salt, but don’t swish around the soap and form a foam.
• Add 2 tablespoons of banana mixture to the detergent mixture. If you’re using a plastic bag, add the detergent mixture to the bag containing the mashed banana.
• Thoroughly mix the ingredients.
• Filter the liquid through a coffee filter or paper towel. A good method is securing the filter over a glass using a rubber band. Or, place the filter inside a funnel and set the funnel over a glass. Because the mixture is thick, it takes time for the liquid to make its way through the filter. Resist the urge to squeeze the filter paper and speed up the process.
• After about 10 minutes, collect the liquid (the filtrate). You can discard the banana and filter paper.
• Drip about 15 milliliters of cold alcohol onto the liquid. Do not stir it. Ideally, you should see a layer of alcohol on top of the banana liquid. Let the alcohol and filtrate sit undisturbed for 4-5 minutes. The DNA precipitates as cloudy or white cottony material at the interface between the alcohol and the banana layers.
• Dip a toothpick, wooden skewer, or thin glass rod into the liquid and slowly rotate it to spool out the DNA. Examine the DNA, using a magnifying glass if available. If you have a microscope, place the blob of DNA onto a slide. Gently tease apart the DNA strands using a toothpick so you can see them better.

How Extracting DNA From a Banana Works

• Mashing the banana increases the surface area of the plant cells and makes extracting the DNA easier. Add water helps separate the cells from each other. The better you blend the banana, the more efficient the extraction.
• Detergents and other surfactants from dishwashing liquid break down the lipid bilayer of the cell wall (in plants), cell membrane, and nuclear membrane.
• In a laboratory setting, enzymes called proteases break down proteins so they can be separated from DNA.
• A lab might add enzymes called ribonucleases to break down RNA, too.
• Salt or sodium chloride removes proteins bound to the DNA and helps the DNA clump together.
• DNA precipitates out of solution in ice-cold alcohol. If the alcohol is too warm, some of the DNA remains dissolved.
• In a lab, the next step is centrifugation. The centrifuge collects the solid DNA as a pellet, so more of it is recovered from the mixture.

DNA Extraction History

DNA extraction predates the discovery of DNA as a molecule. In 1869, Swiss biologist and physician Friedrich Miescher extracted DNA from white blood cell nuclei. He theorized the material he collected play a role in heredity. Since Miescher’s time, scientists have refined extraction methods. In place of alcohol, phenol and chloroform better separate proteins from DNA. Restriction enzymes and polymerase chain reaction (PCR) help researchers amplify DNA, meaning it’s possible to make many copies of DNA from a tiny sample.

• Dahm, R. (January 2008). “Discovering DNA: Friedrich Miescher and the early years of nucleic acid research”. Human Genetics . 122(6): 565–81. doi: 10.1007/s00439-007-0433-0
• Li, Richard (2015). Forensic Biology (2nd ed.). Boca Raton: CRC Press. ISBN 9781439889701.
• Marmur, J. (1961). “A procedure for the isolation of deoxyribonucleic acid from micro-organisms”. Journal of Molecular Biology . 3 (2): 208–IN1. doi: 10.1016/S0022-2836(61)80047-8
• Pääbo, S. (March 1989). “Ancient DNA: extraction, characterization, molecular cloning, and enzymatic amplification”. Proceedings of the National Academy of Sciences of the United States of America . 86 (6): 1939–43. doi: 10.1073/pnas.86.6.1939
• Sambrook, Michael R.; Green, Joseph (2012). Molecular Cloning . (4th ed.). Cold Spring Harbor, N.Y.: Cold Spring Harbor Laboratory Press. ISBN 1936113422.

Related Posts

How To Extract DNA From a Banana

• Cell Biology
• Weather & Climate
• B.A., Biology, Emory University
• A.S., Nursing, Chattahoochee Technical College

Extracting DNA from a banana may sound like a difficult task, but it is not very difficult at all. The process involves a few general steps, including mashing, filtration, precipitation, and extraction.

What You Need

• Liquid soap
• Rubbing alcohol

Here's How

• Using your knife, cut your banana into tiny pieces to expose more of the cells .
• Place your banana pieces in the blender, add a teaspoon of salt and slightly cover the mixture with warm water. The salt will help the DNA stay together during the mashing process.
• Mix in the blender for 5 to 10 seconds making sure the mixture is not too runny.
• Pour the mixture into the glass jar through the strainer. You want the jar to be about half full.
• Add about 2 teaspoons of liquid soap and gently stir the mixture. You should try not to create bubbles when stirring. The soap helps to break down cell membranes to release the DNA.
• Carefully pour very cold rubbing alcohol down the side of the glass stopping near the top.
• Wait for 5 minutes to allow the DNA to separate from the solution.
• Use the toothpicks to extract the DNA that floats to the surface. It will be long and stringy.
• When pouring the alcohol, make sure that two separate layers are being formed (The bottom layer being the banana mixture and the top layer being the alcohol).
• When extracting the DNA , twist the toothpick slowly. Be sure to only remove the DNA from the top layer.
• Try repeating this experiment again using other foods such as an onion or chicken liver.

Process Explained

Mashing the banana exposes a greater surface area from which to extract the DNA. The liquid soap is added to help break down cell membranes to release the DNA. The filtration step (pouring the mixture through the strainer) allows for the collection of the DNA and other cellular substances. The precipitation step (pouring the cold alcohol down the side of the glass) allows the DNA to separate from other cellular substances. Finally, the DNA is removed from the solution by extraction with the toothpicks.

What is DNA?: DNA is a biological molecule that contains genetic information. It is a nucleic acid that is organized into chromosomes. The genetic code found in DNA provides instructions for the production of proteins and all components necessary for the reproduction of life.

Where is DNA Found?: DNA can be found in the nucleus of our cells. Organelles known as mitochondria also produce their own DNA.

What makes up DNA?: DNA is composed of long nucleotide strands.

How is DNA shaped?: DNA commonly exists as a double stranded molecule with a twisted double helical shape .

What is the role of DNA in inheritance?: Genes are inherited through the replication of DNA in the process of meiosis. Half of our chromosomes are inherited from our mother and half from our father.

What is the role of DNA in protein production?: DNA contains the genetic instructions for the production of proteins . DNA is first transcribed into an RNA version of the DNA code (RNA transcript). This RNA message is then translated to produce proteins. Proteins are involved in just about all cell functions and are key molecules in living cells.

More Fun With DNA

Constructing DNA models is a great way to learn about the structure of DNA, as well as DNA replication. You can learn how to make DNA models out of everyday objects including cardboard and jewelry. You can even learn how to make a DNA model using candy .

• 10 Great Biology Activities and Lessons
• How To Make a DNA Model Using Candy
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• An Introduction to DNA Transcription
• What Is Recombinant DNA Technology?
• Carbohydrates: Sugar and Its Derivatives
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• Biology Homework Help
• Life and Work of Francis Crick, Co-Discoverer of DNA's Structure
• Introduction to the Human Genome Project
• DNA Replication Steps and Process
• Learn How Virus Replication Occurs
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• Genetics Basics

How to extract DNA from a banana

What is dna.

DNA is an important part of every living thing. It is found in every single cell of every living thing. DNA is the molecule that carries all the information about how an organism looks and functions. For example, the specific information that your DNA carries is what determines what colour your eyes and hair are. A strand of DNA (like the image on the right) is only 0.000002 mm wide; that’s 35,000 times thinner than an average strand of human hair! Because it’s so small, we need to collect a lot of DNA before we can see it with our naked eyes.

Extracting DNA from a banana

• 1 ripe banana
• ½ cup tap water
• ¼ teaspoon table salt
• 1 teaspoon dish soap
• 2 tablespoon tap water
• ~2-3 tablespoon ice cold 99% alcohol (isopropyl alcohol or ethanol work well)
• 1 plastic bag (or other container for mashing a banana)
• 1 coffee filter
• 2 clear glasses
• 1 skewer or piece of wire
• 1 tube or container to hold your DNA
• Optional string and decorations to make a DNA necklace

Instructions:

• Peel the ripe banana and put it in the plastic bag.
• Add ½ cup of table water to the plastic bag, and mash your banana until it is a smooth consistency.
• Add ¼ teaspoon of table salt, 1 teaspoon of dish soap, and 2 tablespoon of tap water to a glass, and stir gently with a spoon until the salt and soap are dissolved. This will take a few minutes.
• Add 2 tablespoon of the banana mixture to the same glass, and stir for at least 10 minutes.
• Place the coffee filter into the second glass, and secure it with an elastic band.
• Pour the contents of the first glass (banana/soap/salt mixture) into the coffee filter. Allow the liquid to drain through the coffee filter. The liquid that collects in the glass below the coffee filter is called the filtrate. This will take between 10 and 15 minutes. Do not squeeze the coffee filter, as it might rip.
• Estimate the volume of the filtrate, and add a similar amount of ice cold alcohol. Do not stir. Leave the mixture undisturbed for about 5 minutes. You should start to see a white solid forming in the glass. This is your DNA!
• Use a skewer or piece of wire to collect the DNA from the glass, and add it to the tube or container you have prepared to store your DNA.

Add a string to your tube, and turn it into a necklace, keychain, ornament...!

Banana DNA Extraction: Visualizing Deoxyribonucleic Acid

This at home lab shows how to extract DNA from a banana using salt, soap, and rubbing alcohol.

All living things contain genetic information known as DNA (or deoxyribonucleic acid). DNA, along with RNA, are nucleic acids commonly found in the nucleus. These macromolecules provide basic instructions for the growth and development of organisms. Both you and bananas have DNA, yet the specific genes present in the DNA give each of you unique traits. A single DNA molecule forms a double-helix because it consists of two nucleotide strands twisted together. However, you cannot see the shape of a single molecule without a high-powered microscope. But if you extracted all of the DNA out of a piece of banana, then you could see and even touch the DNA.

Download Materials

by Mandy Hartley | Mar 29, 2021

Science at home: How to extract DNA from a banana

Did you know 60% of your DNA is the same as a banana? No? Perhaps your child doesn’t either. Why not try this fun science activity that will allow you to see some DNA from a banana. It helps children create a mental image of DNA and gives them a taste of what being a scientist is like!

How to explain DNA

All living things including humans, plants (bananas!) and animals have DNA (deoxyribonucleic acid). DNA contains the instructions required to build each living thing.

You will need the following:

• Two clear glasses/cups
• Sealable plastic bag
• Blunt knife and teaspoon
• Plate/chopping board
• Measuring jug
• Either a colander/sieve/tea strainer
• Either a coffee filter/dish cloth/paper towel
• Black paper/card/black t-shirt/black jumper
• Vodka/surgical spirit/rubbing alcohol (keep in freezer)
• 4 teaspoons salt
• 2 teaspoons washing up liquid
• Skewer (optional)

This activity requires adult supervision and safety glasses (or regular glasses/sunglasses). Step 1: Chop up the banana. Place the banana onto a plate. Use the knife to chop it up.

Step 2: Put the banana into a bag. Place the banana pieces into a sealable plastic bag.

Step 3. Squash the banana. Close the bag and gently squash the banana until smooth.

Step 4: Add salt to warm water Fill the glass half full with warm water. Add the salt, then stir with a teaspoon until dissolved.

Step 5: Add washing up liquid Add washing up liquid to the glass and stir.

Step 6: Pour into the bag. Pour into the bag. Close the bag and squash gently for 10 minutes.

Step 7: Sieve Put the sieve on top of the jug. Place the coffee filter in the sieve and pour the contents of the bag into it. Let the liquid drain through. This can take a while!

Step 8: Pour the drained liquid into a glass. Pour the drained liquid into a glass. Place on top of the black card. Make sure you are wearing safety glasses!

Step 9: Ask an adult to carefully add the alcohol Have an adult pour the alcohol down the side into your glass. Watch the bottom of your cup! White strands which look like cotton should appear. This is your banana DNA – the instructions to make a banana!

About the author

I was at university when I saw DNA for the first time. Instead of bananas I looked at mosquitoes. (The methods used to get DNA are similar whether it is from humans, plants, animals or even bananas.) I remember holding up the tube and adding the alcohol, like we did with our banana. As if by magic, the white, cotton-like strands of DNA appeared. It had an incredible effect on me – hopefully you and your children will enjoy the activity too.

Scientists all over the world are doing similar activities. It might be with smaller tubes and maybe the chemicals are slightly different but the end result is the same. They get DNA and use it to do things like help identify and treat inherited diseases, make sure there are enough crops to feed the world, catch criminals, solve archaeological mysteries, even create vaccines to prevent the spread of Covid-19.

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Written by Mandy Hartley

Mandy Hartley is a multi-sensory story teller, author and educator. She runs scientific workshops to teach children about DNA and inspire them with a love of science and literacy. Mandy lives in Norfolk with her husband and two children, Annabelle and Harry.

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May 12, 2011

Find the DNA in a Banana

Bring Science Home: Activity 9

By Molly Josephs

Key concepts Cells DNA Genes

From National Science Education Standards : Reproduction and heredity

Introduction What do you have in common with a banana? Even though we might not look alike, all living things—bananas and people included—are made up of the same basic material.

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Just like houses are made up of smaller units such as bricks, all living things are made up trillions of microscopic building blocks called cells. Within an organism, each cell contains a complete set of "blueprints". These directions determine the organism's characteristics.

Background If we could zoom in on a single, tiny cell, we could see an even teenier "container" inside called a nucleus. It holds a stringy substance called DNA, which is like a set of blueprints, or instructions. DNA contains a code for how to build a life-form and put together the features that make that organism unique. Segments, or pieces, of DNA are called "genes". In living things, such as us, each gene determines something about our bodies—a trait. In our DNA there are genes that are responsible for hair color, eye color, earlobe shape and so on. We get our DNA from our parents. Some characteristics, like eye color, are pretty much entirely determined by DNA. Some are determined both by DNA and by your environment as you grow up, like how tall you will be as an adult. And some traits are not very directly tied to DNA at all, like the kind of books you like to read.

Just like us, banana plants have genes and DNA in their cells, and just like us, their DNA determines their traits. Using only our eyes, we couldn't see a single cell or the DNA inside of it. If we remove DNA from millions of cells, however, we will be able to view it without a microscope. That is what we will do today!

Materials •     Ripe banana •     Half cup of water •     Teaspoon of salt •     Resealable zip-top bag •     Dishwashing soap or detergent •     Rubbing alcohol •     Coffee filter •     Narrow glass •     Narrow wooden stirrer

Preparation •     Place your bottle of rubbing alcohol into the refrigerator or freezer and let it chill for the duration of this experiment. •     Peel a banana. •     Put the peeled banana in a resealable zip-top bag and close the bag. •     On a hard surface like a tabletop or kitchen counter, mush the banana in the bag for about a minute until it has a fine, puddinglike consistency and until all lumps are gone. Do not slap the bag or mash the banana too close to the bag's zip seal. (This could cause the seal to open and the banana to squirt out and make a mess.)

Procedure •     Fill a measuring cup with a half cup of hot water and a teaspoon of salt. •     Pour this saltwater into the bag, and close the bag. Gently mix and slosh the saltwater and mashed banana together for 30 to 45 seconds. •     Add a half of a teaspoon of dishwashing detergent or dish soap into the bag. Again, mix around the contents gently. You do not want the mixture to become too foamy. •     Place the bottom half of a coffee filter in a clear glass cup. The top part of the filter should be folded over the rim of the glass to keep it in place. •     Carefully pour the contents of the bag into the filter and let it sit for several minutes until all of the liquid has dripped down into the cup. (You can now throw out the coffee filter and its contents.) •     Take the rubbing alcohol from the refrigerator. Tilt the glass and slowly pour the alcohol down the side of the cup until there is a layer that is 2.5 to five centimeters (one to two inches) thick. You want to keep the alcohol and the liquefied banana as separate as possible, so complete this step slowly. •     Let this two-layered mixture sit for eight minutes. During this time, what do you see happening between the alcohol and the banana liquid layer? It looks cloudy and may have some tiny bubbles in it. The longer you wait, the more defined this layer becomes. This is the DNA pieces clumping together. •     Stick the wooden stirrer into the cup. Spin it in place so that cloudy layer spools around it. Remove the stirrer. Can you capture some of the stringy middle layer on your stirrer and remove it from the cup? The substance that you see on the stirrer is DNA!

Read on for observations, results and more resources.

Observations and results The stringy substance that you see is DNA! It has been removed from the millions and millions of cells that make up the banana. All living things have DNA. The more similar and closely related two living things are, the more similar their DNA is. Every human shares 99 percent of his or her DNA with every other person. Furthermore, human DNA is very similar to that of other species. We share most of our genes, which make up DNA, with fellow primates such as chimpanzees and with other mammals such as mice. We even have genes in common with the banana plant!

In this activity each material plays a specific role in helping to extract the DNA from the cells. For instance, the detergent or soap helps to break down the cell's outer membrane, and the salt helps to separate the DNA from other materials in the cell. And because the DNA doesn't dissolve in alcohol, this substance helps the DNA clump together in a separate layer.

Share your banana DNA observations and results! Leave a comment below or share your photos and feedback on Scientific American 's Facebook page .

Cleanup You can wash the bag and reuse it. Pour the banana liquid and alcohol down the drain and wash out the cup.

More to explore "Can Science Save the Banana?" from Scientific American "Bar Code of Life: DNA tags help classify animals" from Scientific American DNA model activity from CSIRO's Double Helix Science Club DNA Interactive site from Cold Spring Harbor Laboratory My First Book about DNA by Katie Woodard, ages 9–12 Have a Nice DNA by Frances R. Balkwill, ages 9–12

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How to Extract Banana DNA

Last Updated: June 24, 2023

This article was co-authored by wikiHow Staff . Our trained team of editors and researchers validate articles for accuracy and comprehensiveness. wikiHow's Content Management Team carefully monitors the work from our editorial staff to ensure that each article is backed by trusted research and meets our high quality standards. This article has been viewed 12,178 times.

DNA, or deoxyribonucleic acid, is in every living organism on Earth, including all humans and plants. DNA is required because it provides instructions to every cell inside the organism telling it how to grow and what to do. Those instructions are provided through segments of DNA that are called genes. DNA is so small that it cannot be seen with the naked eye. However, there is a way you can extract DNA material that’s large enough to see from fruits like bananas, kiwis, or strawberries. This experiment can easily be done at home and you probably already have most of the stuff needed to do the experiment.

Creating the Mashed Banana Mixture

• Try to use 90% or higher isopropyl alcohol for this experiment. However, if you have isopropyl alcohol at home already that’s at least 70%, you can use that.
• If you don’t have any isopropyl alcohol, you can buy some at a drugstore or pharmacy; it is fairly inexpensive.

• If you don’t have any ripe bananas, leave one out on the counter until it’s almost brown before doing this experiment.
• You can also use a blender to mash the banana if you don’t want to wait for one to ripen.

• You could also try mashing the banana inside the bag with a rolling pin. Simply roll the rolling pin back and forth across the bag until it’s all mashed up.

• Make sure to use really hot, steaming water from the faucet.
• Be careful to only handle the measuring cup by its handle in case it’s really hot.
• Any type of salt will work for this step. However, finer table salt will dissolve faster than chunkier sea salt.

• You may need to allow the salt-water mix to cool a bit before you pour it into the plastic bag.
• If the bag is too hot to handle once the water is inside, use oven mitts to hold it.

• Mix the contents of the bag gently . You want to dissolve all the soap into the banana/salt-water mixture without creating a lot of bubbles.
• You can also use shampoo instead of dish soap. [6] X Research source

Isolating the Banana’s DNA

• Even though you’ve secured the filter with an elastic, you may still need to use your hand to hold the filter in place once you start to pour stuff through it.

• The liquid flowing through the coffee filter is essentially soapy saltwater that contains the DNA molecules of the banana.
• The DNA molecules have been separated from the rest of the banana, therefore, the mashed banana is no longer needed.
• Once all the liquid has moved through the filter, you can discard the filter and its contents.

• Do not pour the isopropyl alcohol directly into the liquid that’s in the glass.
• Once done, you should see two distinct layers of liquid; the banana/soap/salt-water on the bottom and the alcohol on the top. The DNA molecules are currently dissolved in the banana/soap/salt-water mixture.

• You can leave the glass for longer than 8 minutes. The longer you leave it, the more defined the DNA material will become.

Keeping the DNA

• A dollar store is a great place to find a variety of small glass containers that may work for this purpose.
• The isopropyl alcohol doesn’t have to be cold for this step.

• This step provides a great photo opportunity of the DNA.

• Once the DNA is in the alcohol, secure the lid on the bottle and keep it as long as you’d like.

Expert Q&A

Things You’ll Need

• cold isopropyl alcohol (>= 90%)
• ½ banana, ripe and peeled
• 1 US qt (950 mL) resealable plastic freezer bag
• measuring cup
• 1 ⁄ 2   c (120 mL) of hot water
• 1  tsp (4.9 mL) of salt
• measuring spoons
• 1 ⁄ 2   tsp (2.5 mL) of liquid dishwashing soap
• paper coffee filter
• tall, narrow drinking glass
• camera / smartphone

Keeping the DNA You Isolated

• small, clear glass bottle
• isopropyl alcohol
• wood skewer

You Might Also Like

• ↑ https://askabiologist.asu.edu/activities/banana-dna
• ↑ https://www.scientificamerican.com/article/find-the-dna-in-a-banana-bring-science-home/
• ↑ https://www.rhfleet.org/sites/default/files/files/Banana%20DNA%20Extraction.pdf

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How to Extract DNA from a Banana

What makes us like we are? What colour hair, eyes, body shape, whether we are male or female, actually human and not a dog? Well, it’s all coded in our DNA.

DNA for kids to understand can be a challenging subject it’s abstract it’s not like we can see it right? Well you can’t see the actual structure easily you need an electron microscopic to do that but you can see the strands easily that makeup DNA you can extract it from a banana. Here’s a simple experiment to extract DNA so that your child can see the strands from inside the cells.

What You'll Find on This Page

What is DNA

DNA or deoxyribonucleic acid is the material inside the cells of a living thing (apart from some viruses which have RNA instead) that carry the genetic code for making the living thing.

The DNA is divided into small sections called genes and each of these genes carries the information that is needed for how things look and even how things work.

DNA is found in each of the cells of an organism, in most it’s as it’s a complete set with 2 strands joined together with the bases. However, in female and male reproductive cells the DNA is split and that is passed to the offspring to join together to code for the new organism.

As the mixing of the DNA happens this is how variation happens within a population and why we don’t all look exactly the same.

If you would like to make a model of DNA then we enjoyed making this Candy DNA Model from Science Sparks.

Although you won’t be able to see this structure you will be able to collect the DNA and show that it is string-like with this simple science experiment for kids.

We have included affiliate links to some of the products and resources as an associate we may earn from qualifying purchases.

Extracting DNA with Kids

DNA can easily be extracted from soft fruit like bananas as they are easy for kids to mash and puree which breaks some of the cell structures and therefore easier to extract the DNA to view.

We used a banana because that was the softest fruit we had in the house – however, pineapple, strawberry, and kiwi work really well too.

Adult supervision will be needed when it comes to using Isopropyl alcohol

Materials needed for DNA Extraction from a Banana

We have provided instructions for extraction with a Chemistry set, we have this set ( US Amazon , UK Amazon ) if your child prefers and you have a set handy or with simple kitchen equipment.

Common Materials

• Chopping board
• Bamboo Skewer
• Isopropyl alcohol (Rubbing Alcohol) available from the Chemist or on Amazon in the UK a VERY strong vodka may work but we didn’t try that in this experiment
• 1 tea spoon of salt
• Washing-up Liquid (Dish Soap)

Materials from Chemistry Set

• 2 x Beaker or Beaker and Conical Flask
• Stirring Road
• 2 Test tubes
• Test Tube Holder

Materials from The Kitchen

• Plastic bag which seals

Preparation

You will need to place the Isopropyl alcohol into the freezer as you need cold alcohol for this experiment.

Make sure you have a clear and clean workspace. Wear safety glasses whilst conducting the experiment.

1. Cut up half a banana into slices and then quarter these slices.

2. Either place the banana in a beaker or small sealable plastic bag. Then smush it to mush. Use a fork, stirring rod, or similar in the beaker and your hands on the outside of the plastic bag.

3. In either a separate beaker or glass prepare a solution of warm water and dissolve in the teaspoon of salt. Once it’s dissolved add in around 5 small squirts of washing-up liquid and stir.

4. Pour the mixture into the mushed-up bananas and stir thoroughly so that you have a gooey liquidy banana solution.

5. Using the sieve place above a glass or your beaker you used for the water mixture and pour in the banana mixture letting the liquid go through but not the clumps of banana that you may still have left.

6. Now half fill and empty glass or test tube with the solution.

7. Get an adult to fill a test tube about 1cm full or a glass 1/4 full with the Isopropyl alcohol from the freezer.

8. Now gently pour down the side of the test tube or glass. You may find this easier to do with a pipette if you have one available.

9. Observe the layer of white that appears above the banana liquid. Take the skewer and place it into this and bring it out.

That snot-like substance is strands of DNA you can use a microscopy and magnifying glass to see the strands in more detail – full instructions on how to prepare it can be found here (under what does Strawberry DNA look like) as well as instructions for how to extract DNA from a strawberry .

The process explained

DNA is contained within the nucleus of the cells within the banana to extract it we need to break the cells up and the cell membranes so that the DNA is free in the liquid.

Although mashing the banana breaks up some of the cells we need the salt and the soap to fully break down the cell membranes and allow the DNA to form in the liquid.

The soap breaks the cell walls and membranes and then the salt traps the DNA and means that we can actually see it.

The Isopropyl alcohol is needed as DNA doesn’t mix with it and instead, it forms a layer of DNA that we can then put the skewer into and remove to examine.

Where does this fit in Science?

It’s a fun experiment for kids, but where does it fit in science learning?

Here are some ideas of where you could do this experiment.

Learning about Dinosaurs

If you are learning about dinosaurs and the question comes up but could we recreate them now then DNA is essential. Maybe you’ve watched Jurassic Park and seen then extract DNA from the mosquito, you can now see what would have been extracted too.

When Learning about Reproduction

Whether it’s plants or animals a good time to quickly introduce DNA is when talking about sexual reproduction and the female and male sex cells combining to make offspring.

Check out our plant reproductive organ experiment to explore this further.

Evolution, Inheritance and Natural Selection

If you are covering evolution and inheritance then this is a great time before you start to delve into passing characteristics to offspring and mutation to carry out this experiment.

More Fun Experiments for Kids

Are you looking for more fun and simple experiment for kids check out these ideas below

Exploring Transpiration Process in Plants with Celery

Growing Crystals without Borax – Simple Science at Home

Simple Paper Towel Chromatography Experiment for Kids

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Michigan Genetics Resource Center

Banana dna experiment.

This DNA extraction is simple and works every time but the DNA is not pure. Some of the protein is still present. However, it is nice because the students get to see and hold in their hand the substance they have been studying that seems so abstract and hard to believe it even exists.

Materials for each group of students:

• graduated cylinder
• beakers 100ml and 2x250ml (or jars that same size)
• liquid dishwashing detergent (clear solution works better than cloudy)
• 1/2 of a banana
• mortar and pestle
• coffee filter
• rubber band
• COLD  95% ethanol (this is something that you can’t substitute)
• wooden splint
• refrigerator
• Make a 10% solution of dishwashing detergent in one of your 250ml beakers (make enough to fill the mortar half way)
• Slice the banana into the mortar
• Add the 10% detergent solution to cover the fruit
• Add a pinch of salt
• Grind the banana in the soap solution until there are no lumps (this is the hardest part, have the students take turns)
• Fasten a coffee filter to the 250 ml beaker with a rubber band so there is room for the fruit to be poured into the filter
• Pour the fruit and soap mixture into the filter and place in a cold place to filter
• Clean up your lab area while you are waiting for the filtering to complete
• Remove the filter and throw away the contents
• Pour enough of the liquid into a test tube to fill it 2 cm high
• Add twice the volume of 95% ethanol (try to layer the alcohol on top by gently pouring it down the side of the test tube)
• The DNA will precipitate in the boundary between the alcohol and the banana mixture as a cloudy mass
• Spool the DNA onto your wooden splint

Some additional protocols for DNA extractions:

• How to Extract DNA from Anything Living  – This site has a great explanation for each step along with pictures!
• DNA Extraction: Virtual Lab  – This site shows how to extract DNA from human cells.

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DNA (deoxyribonucleic acid): molecular instructions that guide how all living things develop and function... more

Can You Really See DNA?

This short activity helps students visualize one of the most important molecules on the planet, DNA. The activity can be done with simple materials found in most homes. We use bananas, but strawberries or other fruit soft enough to mush up can also be used. The activity is written for students at a middle school or higher level, but with more intense guidance, this activity is useful for students of any age.

Tips for Classroom Implementation

Time Required : 45 minutes

Classroom set-up:

• One container of soap and salt should be more than enough for a large class to use, but we suggest having two of each on hand just in case.
• This activity generally works better with small groups of students each working on their own banana extraction. This also makes it likely that at least one group will have very visible DNA.
• Make sure to have extra zip bags and extra coffee filters on hand, in case any break.
• If a coffee filter breaks and banana mush falls to the bottom of the glass, pour it back into the bag, secure a new filter, and pour the mush back in more slowly, letting it drain as you pour.

When combined with additional reading from Ask A Biologist, or additional short assignments, this DNA extraction activity can meet several learning standards.

• The story “ DNA ABCs ” will help students understand the importance of DNA to life, as well as the chemical and physical structure of DNA.
• The story page “ Getting Genetics Straight ” will help students differentiate between genes and chromosomes, and understand alleles.
• For high school students, the story “ Controlling Genes ” will help them understand protein synthesis.
• ~37 trillion cells in an adult human body (3.7 x 1013)
• 6.5 pico-grams of DNA per cell (6.5 x 10-12)
• ~250 grams of DNA or more (~9 ounces)

• The story “ Building Blocks of Life ” will help students understand the cell structure and function.
• The story “ Cells Living in Cells ” will help students understand the different cell types that exist.
• Students will grasp that small molecules are tangible.
• Students will follow directions and understand that basic chemicals (salts and detergents) can be used to break down cells and cell parts and to make molecules stick to other molecules.
• EXTENSION: Students will gain a basic understanding of the structure of DNA.
• EXTENSION: Students will understand cells and that they broke apart the cell membrane and the nuclear membrane to reach the DNA.

Next Generation Science Standards

High School Life Sciences

HS-LS-1.A:         Structure and Function. All cells contain genetic information in the form of DNA molecules. Genes are regions in the DNA that contain the instructions that code for the formation of proteins, which carry out most of the work of cells.

Arizona Science Standards

Strand 4: Life Science

Concept 1 : Characteristics of Organisms

Kindergarten   PO 1. Distinguish between living things and non-living things.

Grade 6          

(Cellular Extension) PO 2. Describe the basic structure of a cell, including: cell wall, cell membrane, and nucleus.

(Cellular Extension) PO 3. Describe the function of each of the following cell parts: cell wall, cell membrane, and nucleus.

(Cellular Extension) PO 4. Differentiate between plant and animal cells.

Concept 2 : Molecular Basis of Heredity

Grades 9 – 12  (Genetic Extension) PO 1. Analyze the relationships among nucleic acids (DNA, RNA), genes, and chromosomes.

(Genetic Extension) PO 2. Describe the molecular basis of heredity, in viruses and living things, including DNA replication and protein synthesis.

Common Core standards

Grades 6 - 8:

CCSS.ELA-LITERACY.RST.6-8.3

Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks.

CCSS.ELA-LITERACY.RST.6-8.10

By the end of grade 8, read and comprehend science/technical texts in the grades 6-8 text complexity band independently and proficiently.

DNA basics: 8th grade

Getting genetics straight: 8th grade

Building blocks of life: 7th grade

Grades 9 - 10:

CCSS.ELA-LITERACY.RST.9-10.3

Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.

Controlling genes: 9th grade

Cells living in cells: 10th grade

Read more about: Seeing DNA

View citation, bibliographic details:.

• Article: DNA Extraction - For Teachers
• Author(s): Melissa Wilson Sayres
• Publisher: Arizona State University School of Life Sciences Ask A Biologist
• Site name: ASU - Ask A Biologist
• Date published: May 14, 2016
• Date accessed: September 16, 2024
• Link: https://askabiologist.asu.edu/activities/DNA-activity-teachers

Melissa Wilson Sayres. (2016, May 14). DNA Extraction - For Teachers. ASU - Ask A Biologist. Retrieved September 16, 2024 from https://askabiologist.asu.edu/activities/DNA-activity-teachers

Chicago Manual of Style

Melissa Wilson Sayres. "DNA Extraction - For Teachers". ASU - Ask A Biologist. 14 May, 2016. https://askabiologist.asu.edu/activities/DNA-activity-teachers

MLA 2017 Style

Melissa Wilson Sayres. "DNA Extraction - For Teachers". ASU - Ask A Biologist. 14 May 2016. ASU - Ask A Biologist, Web. 16 Sep 2024. https://askabiologist.asu.edu/activities/DNA-activity-teachers

Watch Biologist Melissa Wilson Sayres as she walks you through this experiment in this 4 minute video .

Download the -

Banana DNA activity (PDF)

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The Sydney Morning Herald

The man who saved bananas from certain death – and next, 750,000 children, by angus dalton, save articles for later.

Add articles to your saved list and come back to them any time.

Examine, a free weekly newsletter covering science with a sceptical, evidence-based eye, is sent every Tuesday. You’re reading an excerpt – Sign up to get the whole newsletter in your inbox .

At the start of this century, James Dale chose a formidable opponent.

The virulent fungal pathogen had arrived in Australia in 1997. Scientific name: Fusarium oxysporum f.sp. cubense . My suggestion: the Banana Boogeyman.

The fungus can lurk for years in soils, from cactus-studded deserts to icy tundra. When the fungus comes into contact with a banana plant’s roots, it deploys slender hyphae tentacles that snake into the plant through wounds opened by parasitic weevils and nematode worms.

Panama disease causing wilt in banana plants (left) and brown discolouration in the pseudostem (right). Credit: Department of Agriculture and Fisheries

The fungus strangles the plant’s vascular system and starves its host. By the time symptoms show – yellowing foliage, dead leaves collapsing into a brown skirt, younger leaves stunted to resemble spikes – it’s too late.

The plant dies and the fungus releases plumes of hardy spores. Just one microscopic speck is enough to infect the next plant.

This affliction, Panama disease, decimated the world’s former most popular banana, the Gros Michel. Now a strain of the disease called tropical race 4 threatens the existence of Cavendish bananas, which today make up half of global banana production and account for a $US20 billion ($29.6 billion) industry.

The culprit threatening to wipe out the Cavendish banana: a fungus called Fusarium oxysporum f. sp. cubense. Credit: Wikimedia

Dale, now a distinguished professor at the Queensland University of Technology, has been racing for 25 years to create a banana resistant to the disease. But his method is a controversial one.

The wild saviour

Back in the ’90s and 2000s, genetically modified crops had a bad rap. There were a number of small and disputed animal studies that claimed eating GM foods caused harm.

“Non-GMO” became a ubiquitous marketing slogan. Public suspicion drove a worldwide crackdown on GM crops, including a moratorium in NSW that began in 2003 and only lifted in 2021.

Professor James Dale studying Panama-resistance banana genes in the lab in 2001. Credit: Angela Wylie

But Dale was convinced genetic modification was the only way to save the banana.

As he hunted for a way to make the Cavendish resistant to Panama disease, an American plant pathologist, Ivan Buddenhagen, was in South-East Asia surveying crop fields razed by the fungus.

On one farm, a stand of banana plants grew lush and fruitful amid the destruction. They were wild plants. Buddenhagen gathered their seeds and sent them to Dale.

Seedless, sterile, and susceptible to death

By the hand of human selection, domestic bananas have become seedless and sterile, losing the evolutionary force that could have allowed them to adapt to Panama disease via natural selection.

“Luckily, there are still wild bananas that go through their normal evolutionary process,” Dale says.

In the wild bananas, Dale and his team identified the gene suspected to underpin resistance to Panama disease. A PhD student discovered the RGA2 gene was present in the kind of Cavendish they worked with, the Grand Nain, but it wasn’t “expressed”, or turned on. But it was turned on in the wild bananas. Bingo!

They set to work getting the RGA2 gene into Grand Nains. These were the days before the easy gene-editing tool CRISPR , so they hijacked bacteria to do their bidding.

Professor Dale with a GM banana plant ahead of a field trial in 2017. Credit: Anthony Weate

“Agrobacterium is a natural genetic engineer, that’s its lifestyle,” Dale says. “It infects huge numbers of plants and transfers a bit of its DNA into its host plant. That bit of DNA encodes sugars that only it can live on.”

By swapping out that sugar-producing DNA with the RGA2 gene, the scientists reprogrammed the agrobacterium to deliver the fungus-resistant gene to Grand Nains.

The most important test

Then Dale struck a problem – the team couldn’t do field trials because they weren’t allowed to bring Panama fungus into Queensland.

But then the plant pathologist Buddenhagen came back into frame: he’d met with a Northern Territory farmer who’d bought a patch of land riddled with the fungus in Humpty Doo near Darwin.

The QCAV-4 undergoes its most important test after 25 years of research. Credit: QUT

Buddenhagen introduced Dale to the farmer, who decided to help fund and host the trials. On his field, they tested seven kinds of GM banana plants and found one – QCAV-4 – was particularly resistant to Panama disease.

Their momentum was dashed again when they were forced to destroy those plants in 2015 due to biosecurity measures triggered to control an outbreak of a different disease, banana freckle. But in 2018 they returned to grow 50 QCAV-4 plants. Today, 47 of them are alive and thriving.

In February this year, the government approved the commercial release of the QCAV-4 banana after rigorous regulatory checks and, last week, QUT announced the fruit had passed its most important milestone: the taste test.

“They taste great,” Dale says. “They’re as good as any well-grown Cavendish.”

But will the broader public share this taste for GM fruit?

Allergens and vitamin A

Hundreds of pages of regulatory data submitted to Food Standards Australia New Zealand and the Office of the Gene Technology Regulator – and an enormous amount of work – got QCAV-4 over the line.

One of the regulatory tests involved screening the gene-edited crop for potential allergens and toxins, an important undertaking given that a 1996 study found when scientists transferred genes from brazil nuts into soybeans to improve the crops’ nutritional value, they also transferred allergens from the nuts that could cause anaphylaxis.

But Dale says onerous regulatory requirements hold back innovation in this space. “QCAV-4 is the first genetically modified crop that’s been developed at a university and released in Australia. That gives you an idea of how difficult it is.”

Professor Dale’s bananas biofortified with pro-vitamin A could save thousands of lives if grown in places where people die of nutrient deficiency, such as Uganda. The biofortification gives the GM bananas a “golden” colour (left). Credit: Jean-Yves Paul

He has also developed a “biofortified” banana that could help children suffering from vitamin A deficiency, which kills 750,000 children a year in places such as Uganda. The vitamin-rich plants are ready to go, but the biosecurity bill that would allow the deregulation of the potentially life-saving crop has been held up in the Ugandan parliament since the project started.

“It’s unbelievably frustrating,” Dale says.

Would you eat a GM banana?

Once they’re cleared for allergens and toxins, there’s no compelling evidence GM foods pose a risk to human health. A recent systematic review found studies that reported adverse effects were badly designed, prone to bias, and based on animal studies, “the lowest hierarchy of evidence”.

On home soil, it will be interesting to see how genetically modified foods are embraced as more hit the market. Dale says climate change will leave us no choice but to splice in heat-resistant genes to wheat, that won’t go to seed above certain temperatures.

He is also working on cisgenics, where scientists edit the DNA of crops but don’t introduce genetic material from other species. Cisgenic editing falls outside current definitions of “genetically modified” and skirts regulatory requirements because the process mimics that of natural evolution selecting for random mutations. (Some scientists argue this does constitute GM and that resulting products should be labelled as such.)

As for Dale’s GM bananas, although they have received regulatory approval, there are no plans to roll out QCAV-4 commercially until Panama disease spreads further and poses an existential threat to the industry.

“If it gets really serious, then that’s when we’ll talk with the Australian Banana Growers’ Council as to whether we pull the trigger and start to grow these commercially,” Dale says.

So, tell me, when that happens – will you bite?

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