Study Guide

Energy Flow and Enzymes In the Real World

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  • Health

    You are sitting in the doctor's office with a killer sore throat and feeling like you would rather sell your soul, even if it meant taking a biology exam every day, in exchange for a stop to the throat-throbbing pain. To make matters worse, the doctor looks into your throat and gives you a nice pat on the back and says, “Don’t worry, you’ll be fine. Grab yourself some chicken soup and weather this one out in bed.”

    You think to yourself, “What? Are you kidding me? No pill to make this go away? No antibiotics? Oh well. At least I get to miss the rest of the school day.”

    While you may feel that your doctor is acting with gross incompetence, it turns out that he is following good medical practice. Antibiotics have been widely over-prescribed in recent years, and the consequence of this is worldwide drug resistance. Heck, in some instances, antibiotics were prescribed for viruses, for which they have no effect.

    Antibiotic resistance occurs when the drug is no longer effective at killing the microbe that is making you sick. If you think that this sounds like a frightening prospect, you are dead right. It may very well happen that sometime in the future, when you really need antibiotics to work—after surgery or wound infection are two good examples—the antibiotics you take may not do a whole lot of anything. You might as well buy them a cable package and plop them in front of your 52" flat screen.

    The discovery of antibiotics has had a huge positive impact on human health, for sure, but the possibility that these drugs may lose their effectiveness is scarier than Final Destination 5. Studies have shown that patients who were prescribed an antibiotic by their primary care doctor are more likely to have problems with bacterial resistance for up to 12 months afterward. Gotcha, bacteria.

    In a nicely demonstrated "I'll show you," microbes become resistant to antibiotics in several different ways. For example, microbes can develop a way to degrade the antibiotic. Microbes can prevent the binding of the antibiotic to its target. Microbes can also modify the basic biology of the target protein such that the antibiotic won’t impair it anymore. Nice, huh?

    How do bacteria make these changes to resist the antibiotics? The answer is by acquiring changes in their DNA. A bacterium (a single bacterial cell) can acquire a special change to its DNA sequence that will give it a selective advantage against antibiotics. In a lot of ways, it is like winning the lottery. Just as you buy more lottery tickets in hopes that you will increase your chances of winning, bacteria that acquire many mutations in their DNA are more likely to receive the "magic number" or specific DNA change that confers antibiotic resistance. Antibiotic-resistant DNA sequences can also be transferred from one bacterium to another through a process called horizontal gene transfer.

    We all know that fame and fortune have their downsides, and acquiring an antibiotic-resistant mutation is no different. These DNA changes can result in fundamental changes in a protein’s structure. In some cases, this translates to enzymes that do not function as well. A bacterium that has a bacterial resistance gene can actually grow more slowly when no antibiotic is present than a bacterium that does not have the said DNA change.

    However, when the antibiotic is around, it provides selection pressure, where antibiotic-resistant bacteria gain a selective advantage that outcompetes the bacteria that do not have the DNA change. In other words, that little special bacterium gets free entrance to the VIP, or VIM (Very Important Microbe), club to grow and multiply in the sweet life while his little friends without VIM passes are left out in the cold. Just remember that the next time your doctor prescribes antibiotics when they are not needed, which he or she shouldn't, he or she is basically encouraging evolution that helps antibiotic-resistant bacteria grow and prosper.

  • Biotechnology

    Biotechnology is the field of biology mixed with technology (we know; we are geniuses) where industrial processes are designed to use cells or their enzymes to make human products. This includes not only goods, but also medicines and energy. Here is a rundown of how biotechnology works.

    In many cases, an enzyme that researchers think is potentially useful is first isolated from an organism. Researchers then study the enzyme to figure out how to make it better suited for the manufacturing process. The enzyme can often be produced outside of the original organism. Producing enzymes from a microorganism, such as yeast or bacteria (microorganisms), has several advantages: These microorganisms usually grow cheaply and quickly because they have a short generation time. Furthermore, the enzyme can be modified so that it can better complete a biochemical reaction under industrial production conditions. However, even after scientists "tell" yeast or bacteria to produce the enzyme of interest, they still need to isolate the enzyme from the cells of the producing microorganism without compromising the enzyme's integrity.

    For instance, the cancer drug Taxol is used to treat breast and ovarian cancer. It was initially extracted from bark of the yew tree, known as Taxus brevifolia. However, this extraction process was so difficult that it took about 3000 trees to yield 1 kg, or 1,000 g, of the drug. Scientists have since rammed their noggins together and been able to engineer or tailor the production of Taxol using biotechnology and yeast, which resulted in a more economical and inexpensive way of making it.

  • Environment

    Although the first law of thermodynamics says that energy cannot be created or destroyed, we have learned that not all types of energy can be easily re-created. We are constantly hearing that we only have a limited supply of fossil fuels left as an energy source and that we need to refocus our efforts on "alternative energy" methods like wind, solar, and nuclear energy. Although we may not hear about it as much, fossil fuels are actually used for a lot of things other than energy. For instance, fossil fuels are needed for the production of plastics.

    It is estimated that in the last 10 years, more plastics have been created than were created in the whole last century combined.829165.html">SunChips pulled the bags from the shelves. You can't have your cake and eat it, too, SunChips bag-haters. However, most people agree that the PLA bags are a step in the right direction. In all of this, it does become clear that our current use of plastics and their method of disposal is not sustainable in the long-term. Who knew that potato chips could be such a heavy topic, in more ways than one? Remember the days when potato chips came in boxes? No? Ah, nevermind then. Maybe it's time for some Kettle Chips…

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