DNA in a Bottle!

DNA contains the genetic material for all of the cells in our body. It is contained in the nucleus of a cell and codes for all of the proteins made in our body. It is a double stranded helix that is composed of a phosphate a sugar and a base. It has 4 bases. The purpose of this lab is to precipitate our own DNA from our cheek cells and place it in a glass tube. To do this we have to swab the inside of our cheek and place it in a test tube. We had to swish a cup of salt water around in our mouths to help get the DNA, then we poured the lysis buffer into the tube with our DNA. Then we had to invert the tube to mix the lysis buffer with the water and DNA in the tube. Then we added protease to kill the DNAse that kills DNA. Then we had to place the beaker in a hot water bath so the protease would perform at its highest level for 10 min. Once we got the tube out of the water bath we had to place 10 mL of alcohol in the tube. After that we just had to wait and watch the DNA precipitate.
Once we had the DNA precipitated it appeared as white strands floating in the glass tube we placed it in. It was really cool to see what our own DNA looked like and how much there was for only a small amount of cheek cells. I also thought it was weird once Mr. Chugh explained that there is an enzyme that kills DNA strands because I didn't understand why our body would want to destroy DNA. But then I understood more once he explained that it was for foreign DNA like viruses. That also helped explain why DNA doesn't leave the nucleus, because DNAse is not in the nucleus so it would only kill the DNA of invading cells. I enjoyed being able to walk out of the classroom with a tube of my own DNA hanging around my neck and explaining to people what it was.

Yogurt Lab: Bacteria Tastes Good!

Bacteria are present everywhere in our environment.  They are the most abundant lifeforms on our planet and are present in or on everything in this world.  Bacteria are prokaryotes which means that they are single celled organisms with no separate nucleus to hold their reproductive DNA.  Although, humans associate bacteria with disease, actually only a small number of bacteria cause disease.  We understandably associate them with disease because the ones that do have caused some of the most devastating diseases known to man (cholera, bubonic plague, typhus).  We will base this lab off of Koch's Postulates, which provide the steps for identifying a disease caused by a bacteria.
We will work with the beneficial bacteria that allows found in milk which allows for the production of yogurt (which is more nutritious than milk because it contains enzymes that help break down lactose as well as preventing the growth of dangerous spoilage bacteria).  In this lab we will practice the microbial technique and test Koch's Postulates by isolating the bacteria that allows yogurt to be created when it is fermented with milk.
For the procedure we made our tubes of the yogurt plus milk, milk, yogurt plus ampicilin, and ecoli by mixing the ingredients from the tubes of the substances (ecoli was in an agar plate). then we took them over to the vortex to mix it even more effectively. After that we labeled the tubes and placed them in the incubator overnight. The next day we removed the tubes and tested the pH of the tubes to check to see whether or not they became yogurt or stayed milk, if they became yogurt the pH would be slightly acidic while if they did not then it would remain around neutral. We found that the milk plus yogurt bacteria turned into yogurt in the incubator but the ecoli tube did not turn into yogurt it became spoiled milk. Interestingly, the yogurt plus ampicilin was somewhat of a mixture of the two, the ampicilin did not kill enough of the bacteria that the yogurt making process completely stopped but it did kill enough so it did not become totally yogurt. I found it interesting that the yogurt plus ampicilin became a mixture of the two because I expected the ampicilin to be able to kill all of the yogurt producing bacteria but it could not. We as a group had one main source of error in that we accidentaly mixed a tube with a bleached stick, so we had to observe the bleached tube to test what would happen as well as make a new tube with the right ingredients. (The bleach killed all the yogurt producing bacteria as we expected). But it was cool to be able to see the benefits of some bacteria and be able to test the effectiveness of ampicilin at killing bacteria!