Kiwi Fruit Experiment: Finding the DNA of a kiwi fruit - Think like a scientist (10/10)

Summary

This video script demonstrates a simple kitchen experiment to extract DNA from a kiwi fruit, illustrating the concept of DNA as the blueprint of life. Using household items like salt, water, washing up liquid, and ice-cold alcohol, viewers learn to break down cells, create an extraction buffer, and observe DNA strands forming at the liquid interface. The process highlights the accessibility of scientific exploration and invites participants to an online discussion for further insights into DNA's role and significance.

Takeaways

• 🧬 DNA is the 'blueprint of life' and is present in all living cells, including humans.
• 🔍 DNA is invisible to the naked eye and requires special methods to observe it.
• 🥝 A simple kitchen experiment can be conducted to extract DNA, using a kiwi fruit as an example.
• 🍓 Alternative fruits like onions, strawberries, or even defrosted peas can be used for DNA extraction.
• 🥃 Ice-cold alcohol, such as methylated spirits, vodka, or strong white rum, is needed for the extraction process.
• 🧑‍🍳 The fruit's skin should be removed as it contains less DNA and is mostly dead.
• 🔪 Chopping and mashing the fruit helps break up cells and increase the surface area for DNA extraction.
• 🧪 A mixture of salt, water, and washing up liquid forms an 'extraction buffer' that aids in cell breakdown and DNA preservation.
• 🕒 Warming the fruit mix in lukewarm water for 15 minutes helps to further release DNA.
• 🌊 The DNA can be made visible by straining the fruit mix and adding ice-cold alcohol, which causes the DNA to form visible strands.
• 🔬 The DNA appears as tiny white strands and filaments, which can be extracted using a paper clip.
• 💬 The script encourages viewers to join an online discussion to learn more about DNA and its importance.

Q & A

What is DNA commonly referred to as?

DNA is commonly referred to as the blueprint of life.

Where is DNA found?

DNA is found in all the cells of all living things, including humans.

What is the purpose of using ice-cold alcohol in the experiment?

Ice-cold alcohol is used to separate the DNA from other substances because it is less dense and will float over the surface of the kiwi mix.

What can be used as a substitute for methylated spirits in the experiment?

Vodka or very strong white rum can be used as substitutes for methylated spirits.

Why is the skin of the kiwi fruit removed before the experiment?

The skin of the kiwi fruit is removed because it is mostly dead and does not contain much DNA.

What is the role of the extraction buffer in the DNA extraction process?

The extraction buffer, made of salt, water, and washing up liquid, helps to break up the cells further and prevents the DNA from degrading.

How does mashing the kiwi fruit contribute to the DNA extraction?

Mashing the kiwi fruit breaks up the cells and increases the surface area from which DNA can be extracted.

What is the purpose of warming the kiwi mix in lukewarm water?

Warming the kiwi mix in lukewarm water helps to release more DNA from the cells.

How long should the kiwi mix be left in the warm water?

The kiwi mix should be left in the warm water for 15 minutes to allow for the release of more DNA.

Why is the alcohol poured gently down the side of the glass during the experiment?

The alcohol is poured gently down the side of the glass to allow it to float over the surface of the kiwi mix, facilitating the visualization of DNA.

How can you tell when the DNA is being extracted from the kiwi mix?

The presence of tiny white strands and filaments forming at the join between the alcohol and kiwi mix indicates that DNA is being extracted.

Outlines

00:00

🧬 DNA Extraction from Kiwi Fruit

This paragraph introduces the concept of DNA as the blueprint of life and suggests a simple kitchen experiment to visualize DNA. The speaker plans to extract DNA from a kiwi fruit, but mentions that other fruits or even defrosted peas can be used. The process requires ice-cold alcohol, such as methylated spirits, vodka, or strong white rum, and a fine sieve or coffee filter paper. The speaker begins by peeling and mashing the kiwi to break up the cells, then mixes salt, water, and washing up liquid to create an extraction buffer that helps to further break up the cells and prevent DNA degradation. The mixture is warmed to release more DNA, and after straining, the addition of ice-cold alcohol causes the DNA to become visible as white strands and filaments, which can be extracted using a paper clip.

Keywords

💡DNA

DNA, or deoxyribonucleic acid, is a molecule that carries the genetic instructions for the development, functioning, growth, and reproduction of all known living organisms. In the video, DNA is referred to as the 'blueprint of life,' emphasizing its fundamental role in the biological makeup of living things. The experiment described aims to extract DNA from kiwi fruit, illustrating the presence of DNA in all cells.

💡Cells

Cells are the basic structural and functional units of life. They are the smallest units that can carry out all the processes necessary for life, including the replication of DNA. The script mentions breaking up cells to release DNA, highlighting the cellular structure as a key component in the DNA extraction process.

💡Extraction

Extraction refers to the process of obtaining something from a mixture or compound by physical or chemical means. In the context of the video, DNA extraction involves breaking open the cells of the kiwi fruit to separate the DNA from other cellular components, which is central to the experiment being demonstrated.

💡Methylated Spirits

Methylated spirits, also known as denatured alcohol, is a type of alcohol that has been made unfit for human consumption by adding substances to it. In the script, methylated spirits are used as a non-toxic alternative to ethanol for the DNA extraction process, where its ice-cold temperature helps in the separation of DNA strands.

💡Sieve

A sieve is a tool used to separate larger solid particles from liquids or smaller solid particles. In the video, a fine sieve or coffee filter paper is used to strain the kiwi mix, which helps in separating the DNA from the solid parts of the fruit.

💡Salt

Salt, in this context, is used as a component in the extraction buffer. It helps in breaking down the cells and facilitating the release of DNA. The script mentions mixing salt with water and washing up liquid to create an extraction buffer for the DNA extraction process.

💡Washing Up Liquid

Washing up liquid, or detergent, is used in the script to create an extraction buffer that aids in breaking up the cells and preventing the DNA from degrading. It is an essential part of the mixture used in the DNA extraction process described in the video.

💡Buffer

A buffer is a solution that resists changes in pH when small amounts of acid or base are added to it. In the context of the video, the 'extraction buffer' is a mixture of salt, water, and washing up liquid that helps to maintain a stable environment for the DNA extraction, preventing the DNA from degrading.

💡Mash

Mashing is the process of crushing or pounding something into a pulp or mash. In the script, mashing the kiwi fruit is a crucial step to break up the cells and increase the surface area for DNA extraction, which is essential for obtaining a larger quantity of DNA.

💡Lukewarm

Lukewarm refers to a temperature that is slightly warm, not hot. In the video, the kiwi mix is warmed up to lukewarm by sitting in a bowl of lukewarm water, which helps to further release DNA from the cells.

💡Alcohol

In the context of the video, alcohol, specifically ice-cold methylated spirits, is used to separate the DNA from the other components of the kiwi mix. The alcohol's density allows it to float on the surface of the mixture, facilitating the visualization of DNA strands.

Highlights

DNA is referred to as the blueprint of life and is present in all living cells.

A simple kitchen experiment can make DNA visible.

DNA extraction can be performed using a variety of fruits or vegetables.

Defrosted frozen peas can be used if fresh produce is unavailable.

Ice-cold alcohol, such as methylated spirits, is required for the experiment.

A fine sieve or coffee filter paper is needed to strain the mixture.

Peeling the fruit is the first step to avoid extracting DNA from the dead skin.

Mashing the fruit breaks up cells, increasing the surface area for DNA extraction.

An extraction buffer is made by mixing salt, water, and washing up liquid.

The buffer helps to further break up cells and prevent DNA degradation.

Warming the kiwi mix in lukewarm water aids in the release of more DNA.

Straining the kiwi mix separates the liquid containing the DNA.

Ice-cold alcohol is gently poured to reveal the DNA strands at the liquid interface.

Tiny white strands and filaments visible in the alcohol are the extracted DNA.

DNA can be physically extracted and observed with a simple paper clip.

The experiment demonstrates DNA as the blueprint of life in a tangible way.

Further information and discussion about DNA can be found in the online resources provided by the Open University.

Transcripts

You've probably all heard of DNA. It's usually referred to as the blueprint of life.

Now DNA is in all the cells of all living things, including ourselves.

But it's kind of difficult to comprehend because you can't see it.

Well it turns out that with a very simple

kitchen experiment, you actually can see DNA.

And that's what we're going to do now.

I'm going to extract the DNA from this kiwi fruit.

Now it doesn't have to be a kiwi. You can use an onion, or strawberries.

Raid the fruit bowl and pick what you fancy. You can even use defrosted

frozen peas if you haven't got anything fresh.

You're also going to need some ice cold alcohol.

I'm using methylated spirits, and it needs to be in

the freezer for half an hour before you start the experiment.

You could try something like

vodka or very strong white rum as well.

And you're going to need a fine sieve, or you could use coffee filter paper. I'm just

using a tea strainer.

The first thing I'm going to do

is peel the skin off the kiwi. And that's because it's mostly

dead, and it hasn't got very much DNA in it anyway.

So now I'm going to chop it up into small pieces.

And then I'm going to start mashing

it. This is to start breaking up the cells and to give us

a bigger surface area to extract the DNA from.

The next thing you need to do, is mix together

two grams of salt with 100 millilitres of water.

Add this to five gram of washing up liquid.

So mix the three things together. Try and do it quite gently because

you don't want loads of foam and bubbles.

But you do need to stir until the salt's dissolved.

This is called an extraction buffer.

It doesn't really matter about the terminology. It's

basically going to help to break up the cells even further,

and stop the DNA from degrading.

Next you're going to

add this to your kiwi mix.

Keep mashing because the more you mash, the more DNA you will get.

The final step is just

to warm up the kiwi mix. To do that, I'm just

using a bowl of warm water. I've used boiling water from the kettle, added

some cold, so it's lukewarm. I'm going to leave that

sitting in there for 15 minutes. And again, this is just to help release more of the DNA.

Well that's the 15 minutes up. The next thing is to strain the kiwi mix.

Oh, I'm spilling a bit of it.

Now this lovely green liquid has got our kiwi

DNA in it. But we still can't see it, which is where the

alcohol comes in.

Well that's well and truly ice cold. Now pour

the alcohol very gently down the side of the glass. It

should float out over the surface of the kiwi mix because it's actually less dense.

You need to look very carefully at the join between the two liquids, and you'll see tiny

white strands and filaments forming. That's the kiwi DNA.

And I can just very carefully use a paper clip to start

hooking come of it out.

And that is DNA. The blueprint of life.

Now to find out more about

DNA-- what it does and why it's important-- you

need to join in with the online discussion.

Get More from the Open University

Check out the links on screen now.