Banana DNA: Difference between revisions

Latest revision as of 16:00, 13 April 2016

Biology:	DNA, DNA Extraction
Grade Range:	Elementary School, Middle School, High School
Format:	Hands-on

This space is intended to describe the demonstration that is here. Please use this space to describe in short the demonstration, making sure to mention here if it will require any additional safety equipment or how easily it can be adjusted for varied grade levels. Use this page as a base layout for editing the wiki. Feel free to copy the layout onto other pages, and to put the content as needed into the page.

Materials

Banana or Other Fruit
Gauze
Centrifuge Tubes with Lids (two per group)
Cup or Bowl with Fork
Skewers (one per group)
Ethanol with an Ice Bath
Extraction Solution:
- Liquid Soap
- Salt
- Sodium Citrate
- EDTA

Safety Precautions

Please read the Dry Chemical section of the Demonstration Safety page before performing this demonstration.

Inform students that they should wash their hands after performing this demonstration.

Demonstration

Preparation: prepare the extraction solution. For every 500mL of liquid soap, add:

146g Salt
73g Sodium Citrate
5g EDTA

This demonstration requires about 15mL of the extraction solution for each run, so adjust accordingly for the number of times you expect to present this demonstration. If you'd like, you can pre-mash the fruit for the demonstration, but it is better to mash it as needed.

Give each group of 2-4 students two of the centrifuge tubes, a skewer, and a small wad of gauze. Inform them that they will be extracting DNA from the fruit you brought in.
Mash up the fruit, and give each student a small scoop (about 10mL) in one of their centrifuge tubes. Have them add 15mL of the extraction solution, then put the cap on and shake the tube for 1-2 minutes.
Have the students now put the gauze over the second centrifuge tube, and slowly pour the solution through the gauze to remove any big chunks.
Add between 10 and 20mL of the chilled ethanol into their strained solution, and have them gently swirl it. They will see long strands start to precipitate out! Have them use their skewer to collect the strands and lift them out of the solution. Those strands are the DNA from the fruit!

Why This Works

DNA stands for DeoxyriboNucleic Acid. DNA is your body's instruction manual for living - it's a molecule that stores information on everything about your body. DNA is made up of four different building blocks called base components. These components are Adenine (A), Cytosine (C), Guanine (G), and Thymine (T). A and T can bond, and C and G can bond, which creates two kinds of Base Pairs. These base pairs can then bond with other molecules, like sugar molecules and phosphate molecules, to make a Nucleotide. Nucleotides string together to form Genes, which link together to create our Chromosomes. All the chromosomes in your body are collected into a single Genome that is made up of about three billion base components, and that genome is our DNA!

Almost all of your cells contain two copies of your full genome. This is because your DNA is coiled up in your cells, and it twists into a shape called a double-helix. If you unwound it all, it could stretch almost six feet! The double-helix shape of the DNA makes it easy to duplicate. Since A and T can only bond with each other, and C and G can only bond with each other, your DNA can split down the middle, and then each side can replicate the other. A way to think of it is if you were making a peanut butter and jelly sandwich. If your sandwich has only peanut butter, then you know that it needs the jelly. Likewise, if only has the jelly, then you know it needs the peanut butter! When a cell dies, a nearby cell will split its DNA and separate into two cells. Then each cell can recreate the other half of their DNA by seeing what is missing!

Almost every type of living creature on Earth uses DNA, just like humans. It's the information stored in the DNA that causes differences between organisms and species. You get your DNA from your parents - whatever information their DNA held is passed onto you. This is called genetic inheritance. About 99% of your DNA is the same as mine, and every human being; we all have almost exactly the same DNA. It's the small differences in your DNA that give people different eye colors, hair colors, skin colors, heights and other unique traits. Your DNA is what makes you so unique!

Additional Information

This demonstration pairs well with the Candy DNA.
Fun fact: We share about 98.8% of our DNA with Apes, signifying that we have a common ancestor. We also have shared DNA with mice (90%), cats (90%), dogs (84%), and even flies (50%). However, we do not share 50% of our DNA with bananas. Rather, we share only about 17% of our DNA with bananas, as a conservative estimate. This paper has more information on the banana genome.

@@ Line 1: / Line 1: @@
-== Age ==
+{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
+| [[Biology]]:
+| DNA, DNA Extraction
+|-
+| Grade Range:
+| [[Elementary School]], [[Middle School]], [[High School]]
+|-
+| Format:
+| [[Hands-on]]
+|}
-Elementary School, Middle School, High School
+This space is intended to describe the demonstration that is here. Please use this space to describe in short the demonstration, making sure to mention here if it will require any additional safety equipment or how easily it can be adjusted for varied grade levels.
+Use this page as a base layout for editing the wiki. Feel free to copy the layout onto other pages, and to put the content as needed into the page.
-== Format ==
+== Materials ==
-Hands-on
+* Banana or Other Fruit
+* Gauze
+* Centrifuge Tubes with Lids (two per group)
+* Cup or Bowl with Fork
+* Skewers (one per group)
+* Ethanol with an Ice Bath
+* Extraction Solution:
+** Liquid Soap
+** Salt
+** Sodium Citrate
+** EDTA
-== Material ==
-    Onion
+== Safety Precautions ==
-    Blender
-    Gauze
-    Ice cold ethanol (200 proof)
-    Wooden skewer
-    Spoon
-    Two 50mL centrifuge tubes for each participant
-    DNA extraction solution
-mL/L soap
-.3 g/L EDTA
-.8 g/L NaCl
-.4 G/L citrate
-Safety Precautions: Science Theatre demonstrators must keep the safety of themselves and their audience in mind at all times. All Science Theatre demonstrators must have read through the Safety Training page. The ST Safety Box with first aid kit, fire extinguisher, etc. should always be available to demonstrators. Always wear safety gloves, glasses, and a labcoat if handling chemicals; always perform potentially dangerous demonstrations at a safe distance from the audience; and always keep a very close eye on any volunteers you call from the audience.
+Please read the Dry Chemical section of the [[Demonstration Safety]] page before performing this demonstration.
-== Preparation ==
+Inform students that they should wash their hands after performing this demonstration.
-Make sure the ethanol is very cold - you may wish to keep it in a cooler with dry ice.
-For a large group, you may want to pour out the necessary amounts of the ethanol and extraction solution ahead of time. You may not want to chop the onion/mash the banana too far in advance, since it goes bad sitting out in the air.
 == Demonstration ==
-You may want to introduce this demonstration using the dialogue in the "What to say" section below.
+Preparation: prepare the extraction solution. For every 500mL of liquid soap, add:
+* 146g Salt
-Ideally, students should wear gloves when they participate in the DNA extraction to practice good safety technique. However, with a large group of students, this is not practical. Since the chemicals used aren't dangerous, it is ok to skip using the gloves, but do explain to the students that chemists working with dangerous chemicals always wear gloves and that they should still be careful not to spill. Their hands may get sticky, so tell them to wash them afterwards.
+* 73g Sodium Citrate
+* 5g EDTA
-Onions are more like people than you might think. They use DNA to produce proteins and duplicate calls, too.
+This demonstration requires about 15mL of the extraction solution for each run, so adjust accordingly for the number of times you expect to present this demonstration. If you'd like, you can pre-mash the fruit for the demonstration, but it is better to mash it as needed.
-Do any of you know farmers that grow onions?
-Scientists spend years using sophisticated equipment to study DNA very carefully. We can't show you how to do that, but we can help you take a quick look at DNA by extracting it from this onion.
-Everyone needs two of these centrifuge tubes. I'm going to give you a spoonful of onion that I've pulverized in this blender. By breaking the onion down into tiny bits, we've exposed lots of cells that used to be on the inside of the onion.
-Now I'm going to pour about 15mL of a DNA extraction solution into all of your tubes. The solution is mostly dish soap and salt -the soap breaks down the cell walls that contain the DNA, the salt helps separate the DNA from the rest of the molecules in the cell.
-Gently mix the solution in with the onion pulp so that the chemicals in the solution touch every bit of the onion. Now you've got DNA floating around in your tube, but I bet you can't see it! We need to get rid of everything else in there first.
-Now put the gauze on top of your second centrifuge tube. Push down on the gauze to make a little indentation. Pour your solution onto the indentation and lit it drain. Once nothing more is being strained, throw away the gauze and the pulp.
-Now I'm going to give each of you about 20mL of cold ethanol. The ethanol will dissolve most of the material in the tube, leaving just the DNA behind.
-Can you see little strings in the ethanol? That's DNA!! It's just like the DNA in your own cells.
-You can pull the DNA out of the tube using a wooden skewer.
-If you take more precaution when you do this experiment, you can get more DNA from the onion. Bananas work even better. Search online for "DNA Extraction" for more information, if you're interested.
-== What to Say ==
-Does anyone know what DNA is? Do you want to see what it looks like? We can show you! First, you need to know a little about it.
-DNA stands for deoxyribonucleic acid
-DNA is your body's instruction manual for living - it's a molecule that stores information that it transfers to another chemical (RNA) which tells your ribosomes, little machines in almost every one of your cells, how to make the proteins that make your body work.
-Proteins can send messages, eliminate unwanted viruses and bacteria, and even break down food to give you energy.
-DNA is made up of four different building blocks called base components.
-    Adenine, called "A"
-    Guanine, called "G"
-    Cytosine, called "C"
-    Thymine, called "T"
-The bases combines in different patterns to store ant kind of information the body needs to operate.
-These building blocks combine into bigger structures:
-A and T or C and G can combine to make a base pair.
-A base pair, a sugar molecule, and a phosphate molecule can combine to make a nucleotide.
-Nucleotides string together to form genes, which are make from so many base components combined in such a specific order that they represent some information.
+# Give each group of 2-4 students two of the centrifuge tubes, a skewer, and a small wad of gauze. Inform them that they will be extracting DNA from the fruit you brought in.
+# Mash up the fruit, and give each student a small scoop (about 10mL) in one of their centrifuge tubes. Have them add 15mL of the extraction solution, then put the cap on and shake the tube for 1-2 minutes.
+# Have the students now put the gauze over the second centrifuge tube, and slowly pour the solution through the gauze to remove any big chunks.
+# Add between 10 and 20mL of the chilled ethanol into their strained solution, and have them gently swirl it. They will see long strands start to precipitate out! Have them use their skewer to collect the strands and lift them out of the solution. Those strands are the DNA from the fruit!
-Genes link together to form long strings called chromosomes.
-All the chromosomes in your body are collected into a single genomes that's made up of about three billion base components. Almost all of your cells contain two copies of your full genome. Your DNA gets coiled up into a shape called a double-helix - it looks kind of like a double helix. If you unwound it all, it would stretch about six feet!
+== Why This Works ==
-Almost every type of living creature on Earth uses DNA, just like humans. It's the information stored in the DNA that makes us different than other organisms.
+'''DNA''' stands for '''D'''eoxyribo'''N'''ucleic '''A'''cid. DNA is your body's instruction manual for living - it's a molecule that stores information on everything about your body. DNA is made up of four different building blocks called base components. These components are ''Adenine'' ('''A'''), ''Cytosine'' ('''C'''), ''Guanine'' ('''G'''), and ''Thymine'' ('''T'''). '''A''' and '''T''' can bond, and '''C''' and '''G''' can bond, which creates two kinds of ''Base Pairs''. These base pairs can then bond with other molecules, like sugar molecules and phosphate molecules, to make a ''Nucleotide''. Nucleotides string together to form ''Genes'', which link together to create our ''Chromosomes''. All the chromosomes in your body are collected into a single ''Genome'' that is made up of about three billion base components, and that genome is our DNA!
-You get your DNA from your parents - whatever information their DNA held is passed onto you. This is called genetic inheritance.
+Almost all of your cells contain two copies of your full genome. This is because your DNA is coiled up in your cells, and it twists into a shape called a ''double-helix''. If you unwound it all, it could stretch almost six feet! The double-helix shape of the DNA makes it easy to duplicate. Since '''A''' and '''T''' can only bond with each other, and '''C''' and '''G''' can only bond with each other, your DNA can split down the middle, and then each side can replicate the other. A way to think of it is if you were making a peanut butter and jelly sandwich. If your sandwich has only peanut butter, then you know that it needs the jelly. Likewise, if only has the jelly, then you know it needs the peanut butter! When a cell dies, a nearby cell will split its DNA and separate into two cells. Then each cell can recreate the other half of their DNA by seeing what is missing!
-About 99% of your genome is the same as mine - every human being has almost exactly the same DNA. It's the small differences that give some people blonde hair, some people brown eyes, and even make you more likely to get certain diseases.
+Almost every type of living creature on Earth uses DNA, just like humans. It's the information stored in the DNA that causes differences between organisms and species. You get your DNA from your parents - whatever information their DNA held is passed onto you. This is called ''genetic inheritance''. About 99% of your DNA is the same as mine, and every human being; we all have almost exactly the same DNA. It's the small differences in your DNA that give people different eye colors, hair colors, skin colors, heights and other unique traits. Your DNA is what makes you so unique!
-The double-helix shape of the DNA makes it easy to duplicate. Imagine cutting a spiral staircase in half - it would be easy to figure our where you need to complete each step on each side to make two new staircases.
+== Additional Information ==
-If your body ever needs another skin cell, an existing skin cell will split its DNA in half to create two copies: one for the old cell and another for the new one.
+* This demonstration pairs well with the [[Candy DNA]].
+* Fun fact: We share about 98.8% of our DNA with Apes, signifying that we have a common ancestor. We also have shared DNA with mice (90%), cats (90%), dogs (84%), and even flies (50%). However, we do '''''not''''' share 50% of our DNA with bananas. Rather, we share only about 17% of our DNA with bananas, as a conservative estimate. [http://www.nature.com/nature/journal/v488/n7410/full/nature11241.html#supplementary-information This paper] has more information on the banana genome.