Introduction: How to Extract Dino DNA
Okay, my mistake, you'll need a Dino to do this.
Instead of pretending you are a paleontologist how about pretending you are a forensic scientist, and extract some other kind of DNA.
First, you will need a-not-so-hard-to-find source of DNA.
Don't worry, this process does not require you or anyone to suffer any pain.
Sources of DNA are plentiful because DNA literally grows on trees. DNA is found in the nucleus of plant cells and plant cells can be found in hundreds of places, not just in trees.
Plant DNA can often be found at the scene of a crime or on the victim or suspect, placing them together at some point in time.
For this Instructable I'm going to use plant DNA. Most plants have eight units of DNA or 8 copies of each chromosome per cell (called Octoploids) instead of just 2 copies as in most animal cells (called Diploids) or only one copy, as in sperm cells (called Haploids).
For this Instructable I've chosen cells from ripe strawberries because in addition to having lots of DNA they also have lots of enzymes to help break down cell walls.
In the absence of strawberries most any kind of ripe fruit, like watermelon, bananas or kiwi, can be used - although less DNA can be extracted.
Step 1: Prepare the Precipitant
First place a bottle of 91% Isopropyl alcohol in the freezer.
Although Isopropyl will not freeze it will get ice cold and expand, so be sure there is enough air space in the bottle for expansion.
(You may also want to chill a small bottle or a beaker to make pouring the alcohol into a test tube or other sample retainer a lot easier later on.)
Step 2: Prepare the Sample
Place 2 or 3 strawberries with the sepals removed into a freezer bag.
Add 1/8 teaspoon of non-ionized table salt to one cup of water and pour into the bag with the strawberries.
The salt will dissolve proteins in the cell and help keep them separated from the DNA.
Seal the bag and mash up the strawberries to break the cells apart and expose their contents to the salt water.
faust says frozen strawberries work fine and to focus on the mashing for a greater yield.
Step 3: Make the Extraction Buffer
The extraction buffer is made by adding a couple of tablespoons of detergent to the contents of the freezer bag. Cell walls are made of bilayer lipids which the detergent will help to dissolve.
Step 4: Filter the Sample
Place a paper towel that has been folded into quarters with one quarter open into a funnel for use as a filter. Moisten with water after the paper towel is in place. If you have plenty of time then cut the excess paper towel off. In fact the more time you give each step the greater the yield of DNA will be.
Next separate the liquid in the sample from the solids by pouring it through the filter into a narrow jar or a test tube.
Do not squeeze the liquid through the filter but use only the liquid which drains through the paper towel, unassisted from touching, wiping or squeezing and only by gravity.
Step 5: Precipitate the DNA
Retrieve the bottle of cold Isopropyl from the freezer ( Tip: You may want to transfer the amount of alcohol you are going to use to a beaker or other container with a beak or spout which is smaller and has been chilled. This will help prevent the alcohol from dripping or spilling when it is poured).
Slowly add the the alcohol to the test tube by pouring it down the inside of the test tube surface without allowing it to mix with the sample, so the alcohol and sample remain in separate layers.
After a few minutes a cloudy layer will form between the alcohol and sample layers. This is DNA that has precipitated out of the sample solution into the alcohol in clumps of DNA molecules composed of long strands. Handle gently or you will break the strands apart. Enzymes in the sample solution from inside the cells and outside the neuclius will also break the DNA strands apart. This process can be reduced by removing the DNA from the test tube and placing it in a 50% solution of Isopropyl for storage.
You can wind the strands around a glass rod or wire hook to remove then from the test tube.
If you have a microscope you can pull apart and separate the stands with a couple of pins to take a closer look.
Here is a link to a site with a more detailed and comprehensive description of this process, if you want to learn and do more.
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