Biofuels: Fueling the Future

In our society, gasoline is becoming one of the most used and most expensive substances. Gasoline prices can rise dramatically, and we are at their mercy. However, there is a light at the end of the tunnel. A new concept, biofuels, have scientists working to find an alternative source of fuel. What are biofuels? Plant fiber contains a lot of sugar, but it is locked away securely. Scientists use enzymes such as E. Coli to break down these fibers and consume the sugars. (The molecule combined by an enzyme is called the substrate.) When this occurs,  substances such as ethanol are released, and these can be used as fuel. This idea is very important in today's world so that we can eliminate our dependence on oil. In this lab, we will combine cellulose, a plant fiber, with an enzyme called cellobiase that breaks down cellulose. Cellulose is comprised of two glucose molecules bonded together. When the enzyme breaks this bond, two individual glucose molecules are released and can be used as fuel. However, we are not able to see how fast this reaction is occurring. In order to observe the reaction's speed, we will add a mixture of cellobiase and an alternative substrate into five separate containers. This mixture creates glucose and P-nitrophenol. To these containers we will add stop solution at different time intervals. The stop solution will kill the cellobiase, essentially taking a snapshot of the reaction. The stop solution will also turn the P-nitrophenol yellow. By adding this at different time intervals, we can observe the differences between each container. Depending on the intensity of the yellow coloration, we know how far along the reaction is. On the next day, we will grind up mushrooms, creating a fungus extract, to add to the solution. Fungus contains many enzymes so adding this will speed up the reaction. We will compare different types of fungi to determine which type speeds the reaction up the most.

DNA Precipitation Results

In this lab, everything luckily worked out as planned. We followed all the steps correctly so our DNA precipitated very easily. It was necessary to slowly tilt the vial back and forth after adding any ingredient in order to evenly and gently distribute it. After the DNA precipitated, it was very difficult to extract it to put into the vial because it was fragile and hard to get into the eyedropper. It eventually worked and we had our DNA necklaces. This lab was a great way to learn about how DNA works and how crucial it is to scientists. Some possible errors we could have made would be to mix the ingredients too vigorously causing the DNA to break up or to add not enough of either the lysis buffer or protease which would prevent the DNA from fully unravelling. Overall, this was a very successful lab.

DNA Bling

DNA is what contains all of the body's information. Stored in the nucleus, it is one of the most crucial parts of the human body. DNA is in the structure of a double helix with the phosphates on the outside and bases on the inside. The bases are in unique patterns that also contain genes that affect your human characteristics such as eye color or hair color. In this lab, we will precipitate DNA, concentrating it to make it visible to the human eye. This same procedure is used in modern day science and has many applications including cloning and crime scene investigation. The first step we need to take in this procedure is to loosen the cheek cells that we will extract to DNA from. To do this, we will gently chew the inside of our cheeks to loosen the cells. After this, we will put a saline solution in our mouths and swish it around to collect the cells, then spit it back into a container. The saline solution has the same pH as the human body, ensuring that the cells will stay alive. Next, we will add the lysis buffer which causes the cells to lyse, or rupture their cell walls. After this is complete, the DNA are freely moving around the saline solution. However, they are tightly coiled around proteins called histones, and in order to precipitate the DNA, we need to uncoil them. In order to do this, we add protease, an enzyme that breaks down proteins so that the DNA comes unwrapped. Then we put the containers into a hot water bath that accelerates the reaction. In a couple of minutes, we will add cold ethanol to the solution to precipitate the DNA. We use ethanol because its freezing point is much lower than water's so it can be very cold and still be a liquid. When the DNA has precipitated, we will extract the large amount of DNA and put it into a necklace which we will wear with pride.

Yogurt Lab: What Happened?

So after we went through the yogurt lab procedure and put all four tubes in a warm bath overnight, what happened?

We collected the tubes and observed the changes that occurred and discovered some pretty interesting information. The control tube of just milk did not turn into yogurt. Obviously there was some spoilage bacteria that cultured overnight because the milk smelled quite sour. The tube with a dollop of yogurt added to it cultured overnight and the entire tube had started to turn into yogurt. This confirms our hypothesis that the yogurt would grow overnight in the tube. However, the tube with E. Coli did not turn into yogurt, proving that not all types of bacteria have the ability to create yogurt. The tube with ampicillin, an antibiotic, did not create yogurt. Because ampicillin killed the bacteria in the milk, there was no way it could culture into yogurt. Overall, we learned that bacteria is able to reproduce very quickly in a favorable environment. A small amount of yogurt added to milk can be cultured into more yogurt if the bacteria are able to reproduce. However, not all types of bacteria cause milk to transform into yogurt, and some types of bacteria cause the milk to spoil. If an antibiotic is added to the milk, it can be preserved in its natural state without spoiling or turning into yogurt. We were careful in our procedure but there are many sources of error that we could have encountered. Factors like not adding the correct amount of an ingredient, using any tools that were not sterile, or not putting the caps on the tubes correctly could have greatly affected our results.

Milk + Bacteria= ?

For over a hundred years, people have wondered about bacteria. While it is undeniable that bacteria play an important role in society, many people wonder what that role is. Bacteria are the single most successful life form on earth. There are more bacteria in one persons mouth than there are people in the entire world. Most people assume that all bacteria are bad. Most people associate bacteria with disease, but only a very small percentage of bacteria are even capable of causing disease. Contrary to popular belief, most bacteria are beneficial. Bacteria in the human body help keep it running smoothly. Some bacteria can even transform substances, as is the case with yogurt. When E. Coli bacteria are present in milk under the right conditions, they can change it into yogurt. Although there are living colonies of bacteria present in yogurt, they are not harmful. In fact, they are good for the human body and can aide in digestion. In this lab, we will use Koch's postulates and play the role of a scientist. Using bacteria, we will be able to create our own yogurt. First we will introduce the E. Coli bacteria into the milk and heat the milk to 80 degrees Celsius in one beaker. In another, we will take a dollop of yogurt with the milk and also heat it. This process is called scalding and it is used to kill spoilage bacteria. After scalding the milk, the milk sugar, called lactose, turns into lactic acid. (this process is called curdling) This also lowers the pH of the milk, killing spoilage bacteria which is why it is possible to leave yogurt unrefrigerated for a long period of time without it spoiling. This process is denatures the milk protein, called casein. At the end of this procedure, the milk is covered and stored in a warm climate for 24-48 hours. After this is completed, the milk will have transformed into a completely new substance: yogurt!