There is one little piece of us, though, that holds the secret to our existence, and the history of our species: The DNA.

My main interest is usually physics and astronomy, but I have always been fascinated by that double-helix molecule and its meaning, both philosophically and realistically; since the beginning of Genetics the human race have progressed exponentially. It’s just, simply, amazing.

Biology lab in the kitchen!

I am about to show you how to extract your own DNA from your own bodies in your own kitchen. Yourselves.

It’s aliiiiiiiiiive!

The Experiment

This experiment allows you to extract DNA matter from cells from your mouth, and is very similar to what Friedrich Miescher discovered. His discovery was from pus, and this one is from your mouth. Physiology can be funny like that.

What do you need?

For this experiment,you will need the following tools:

• Two beakers.
• A glass or a cup. You can use one from the previous experiment.
• Liquid soap (NOT antibacterial. You shouldn’t use those at all anyways).
• 2 test tubes or clean and clear bottles. I used “travel-size”empty plastic bottles for the experiment. These work, just make sure they are properly cleaned with distilled water.
• Distilled water.
• Rubbing Alcohol.
• Sodium Chloride. Well, Salt.
  Sodium Chloride is a nice and fancy way of saying “Salt”. You don’t need anything other than table salt, or cooking salt, but for fun, I suggest going to your nearest pharmacy and try to ask for a small amount of Sodium Chloride.
  I did, and the nice lady replied it is a prescription drug. Worth the chuckling, I promise.
• Glass rod (I used wood, because I didn’t have glass, but wood isn’t as good at all.. try to get a glass rod).
• Anything that can be used to measure the liquids. The more accurate your solutions are formed, the better your results would be.
• Drinking water. Preferably bottled water, to avoid varying amounts of chloride or other contaminants.

The Process

You can find the process I used for this experiment in the repository of About.com biology expert, but here’s a short summary:

1. Solution #1 (Negative-charge Ions to bond the DNA molecules together): 8% Sodium Chloride + 92% Distilled Water.
2. Solution #2 (Breaking apart the cell membranes and “freeing” the DNA from the nucleus): 25% Liquid Soap + 75% Distilled Water.
3. Wash your mouth thoroughly; you want DNA from the cells in your cheek and not from whatever animal (or fruit) you ate for lunch. Make sure your mouth is CLEAN.
4. Swirl about 10ml of water in your mouth. Use the bottled water and NOT the distilled water! If you want a larger amount of cells, do it a bit ‘stronger’. Do that for about 30 seconds.
5. Spit the water into the cup. You have just gathered a bit of cells from your own body, congratulations.
6. Take 1ml of Solution #1 (Sodium Chloride) and add it into an empty, clean bottle (or test tube).
7. Add the cell-water mix you just spit out into the same bottle (or test tube).
8. Add 1ml of Solution #2 (Liquid Soap) into the same bottle (or test tube).
9. Close the cap or seal with a test tube stopper.
10. Twirl, swirl, and turn the bottle upside down and right side up gently. Do not shake. You’re not 007.
11. Add 5ml of Rubbing Alcohol into the bottle while tilting it slightly so the alcohol ends up floating on top of your mixed solutions.
12. Wait for about 5 minutes.
13. Watch. If you want, you can do what I did and move the DNA strand from the solution bottle to a clear bottle that contains alcohol only. I keep my little creation next to my computer screen.
    Make sure you do it very gently.

What’s happening?

Well, DNA exists inside the nucleus of a cell. So to see it, you need to first let it out of its confinement. But that isn’t enough – DNA molecules are positive charge, so they reject one another. In order to see the strand, we need to make sure a bunch of these molecules bond together. Finally, DNA melts in water but not in alcohol – we will use that to “trap” the strand so we can look at it.

So, here’s the summary:

1. Soap has detergent in it, that dissolves the membranes (the “skin” of the cell) and releases the DNA from the nucleus.
2. Sodium Chloride is negatively charged, so it bonds the DNA strands together to create a long strand we can see in the naked eye.
   Correction:
   Okay, I got this wrong again, so ailboles was kind enough to explain it and give links, too!:DNA is a negatively charged molecule. It is the positive ions (in the Sodium Chloride solution) that interact with the DNA (see http://ppge.ucdavis.edu/Equipment/Protocols/thymus_dna_extraction_03.pdf under the section, “Answers to Student Activity” number 5)
   
   Well, that makes more sense. Thanks again to ailboles for taking the time and effort to explain this again!
3. Alcohol “traps” the strand, because it doesn’t break apart in alcohol, only in water.

There you have it. Your own DNA in a bottle. Beats wooden boats any day.

About Scientific Discoveries

Usually, when we hear that someone a long long time ago made a very big discovery we tend to be skeptical. It’s understandable – I find it hard to see anyone getting along without a fast-paced computer, let alone working without an electron microscope, or a light bulb.

But the truth is, usually scientific discoveries don’t just “pop up” miraculously. We tend to remember the people who invented specific “gizmos”, or wrote a patent relating to a specific discovery (like Edison and the Light bulb, Bell’s telephone, and Morse’s telegraph), but they were rarely “the first”. The research started a long time before, and their discoveries were possible only due to past discoveries.

The same is true to DNA.

The 1869 Discovery

In 1962, James D. Watson, Francis Crick and Maurice Wilkins recieved the Nobel Prize for the discovery of the structure of DNA and its hereditary role. Because the Nobel Prize is a famous honor, we tend to remember them specifically, but their discovery was possible because of many prior researches, the first of which was done by a Swiss researcher called Friedrich Miescher in 1869.

Miescher researched the human cells, specifically white blood cells, by taking blood-stained bandages from a nearby hostpital. He noticed a microscopic substance inside the pus on the bandages – and identified the substance as coming from within a cell’s nucleus. He called this substance “Nuclein”.

The following dates mark the time line that lead to the famous discovery of the DNA structure in the 1950s:

• 1869 - Friedrich Miescher identifies a substance that came out of a cell’s nucleus and has a weak acidic properties. He calls it “Nuclein“.
• 1919 - Phoebus Levene identifies the base, sugar and phosphate nucleotide units. He suggests that DNA is made of strings of nucleotide units that are connected together through phosphate groups.
• 1928 – Frederick Griffith combined “smooth” and “rough” forms of Pneumococcus bacteria, showing that DNA plays a role in passing genetic information.
• 1937 - William Astbury produces an X-Ray diffraction pattern that shows DNA has a regular structure.
• 1943 – Oswald Avery, Colin MacLeod and Maclyn McCarty identify DNA as the transforming principle – showing that bacteria transfers genetic information through a process called “Transformation”.
• 1952 – Alfred Hershey and Martha Chase confirmed the heredity trait of DNA in an experiment.
• 1953 - The structure of DNA is suggested by James D. Watson and Francis Crick, based on X-Ray Diffraction images taken by Rosalind Franklin. This is the structure that is accepted today.
• 1957 - Crick lays out the “Central Dogma” of molecular biology, including RNA, DNA and proteins, and the relationships between them.
• 1963 - Watson, Crick and Wilkins receive the Nobel Prize in Physiology or Medicine.

Practical Applications

Wow. That’s going to be a huge huge list. The discovery of Genes, structure of DNA and Genetics in general has led to countless advancements in medicine and technology. From discovering diseases earlier to devising vaccines. The list is just too great, too big, and too important to summarize in a single post. If you look at the resources, however, you could find many places to start.

• Forensic Medicine.
• Interpol’s Attempt – DNA Profiling.
• The study of Human evolution (many more resources, including this one from National Geographic, and Berkley’s “DNA, the Language of Evolution“).

Resources:

• The Experiment Instructions can be found here: http://biology.about.com/c/ht/00/07/How_Extract_DNA_Human0962932481.htm
• Extracting DNA From Fruit:
  • http://www.funsci.com/fun3_en/dna/dna.htm
  • http://www.csiro.au/resources/ps1tp.html
• Great Clip about DNA Structure: http://www.youtube.com/watch?v=qy8dk5iS1f0
• Friedrich Miescher: http://en.wikipedia.org/wiki/Friedrich_Miescher
• Albrecht Kossel: http://en.wikipedia.org/wiki/Albrecht_Kossel
• History of Electricity Discoveries: http://www.code-electrical.com/historyofelectricity.html
• Griffith’s Experiment: http://en.wikipedia.org/wiki/Griffith%27s_experiment
• Hershey-Chase Experiment: http://en.wikipedia.org/wiki/Hershey-Chase_experiment

Well, this is more of a “Show off your geektitude” physics trick that will amaze and enchant your buddies anywhere! Okay, well, maybe not anywhere. Or anyone. But it is geeky, I promise. And will get you some attention.

And it’s cool.

And it’s useful. For parties.

I can switch the contents of two glasses without using a third glass. Yes, I can. Don’t believe me? Well – When in doubt, try it out!

So. Anyone who asks a bartender for anything “on the rocks” knows that alcohol and water do not mix. Not properly, anyways. Not without insistent help. The alcohol always ends up floating on top of the excess water that melted off of the ice. But why?

Well, that has to do with the density of both liquids. Dense materials sink, and less-dense materials float. Water is denser than alcohol, so the alcohol floats on top of the water.

Density also changes with temperature. Water is denser when it’s cold. In higher temperature, the density is lower. Hotter water will always “want” to rise up above colder water. And we’re using this property in this nifty trick. Did I say it was cool?

What is Density?

Density is the measurement of mass per unit of volume. Put simply, it is the amount of particles within a specific space in the material used. A bar of gold will have a lot of particles within 1cm cube volume, while water fume will have very few in the same space. So gold is denser than fume. Which is why we choose to wear it as jewelry.

In physics, the general formula is represented by p=m/v, which means that density is mass per volume. If you know the mass and you know the volume (both quite easy to figure out), you can find the density of objects. This is another cool experiment that will be coming up in the future, and you can try it out yourselves with anything, really, as long as you know its volume (size) and weight (and can figure out the mass). Just be careful who you ask..

Why leave a small hole between the cups?

We don’t want our two liquids to mix, we want them to “switch”. When you leave a tiny hole between both cups, a stream of liquid from the bottom cup is flowing upwards, because it’s lighter, and is replaced by a stream of liquid from the top cup (the ‘heavier’ liquid). If we completely discard of our separator, the liquids will simply mix, and we will have diluted alcohol. Or room-temperature water.

When the process is allowed to happen slowly, after a few minutes, both cups are completely filled with the opposite liquids.

Maaaaaagic! Well, no. Physics.

I mean… Phyyyyyyyyyyyyyyyyyysics!

Materials needed for the Experiment

• Two cups of the same size.
• Alcohol
• Water.
• Credit Card / MTA Card / Cardboard.

Don’t drink and drive.
We will go over momentum in future experiments, but this is one thing you all should know.

Practical Applications

You mean other than being the star of a party? Oh, okay okay, here are a few practical applications for knowing the density and buoyancy of liquids:

• Buoyancy! The density of liquids affect their buoyancy. The lowest dry point on earth, for example, the Dead Sea, has a very high salinity, which makes its density a lot higher than regular ocean water. As a result, people (and other objects) float. Without trying.
• Distant Stars: Astronomers can calculate the density of stars from their mass and volume, and understand better about the process that is “running” the star.

Resources

• Water Density: http://www.4physics.com/phy_demo/Galileo_thermometer/galileo-thermometer-d.html
• Water’s Density and the Relation to Temperature: http://www.simetric.co.uk/si_water.htm
• Oil floats on Water: http://www.physlink.com/Education/AskExperts/ae105.cfm