Four Nutritional Categories in Microbes and the Polymerase Chain Reaction (PCR)

Summary:
Directions for the students: There are 4 essay questions. Please be sure to complete all of them with thorough substantive responses. Citations are required for all responses.
1. Provide an example of an organism within each of the four main nutritional categories of microbes and describe how each obtains its essential nutrients.
2. Provide evidence in support of or refuting the following statement: Microbial life can exist in the complete absence of both sunlight or organic nutrients.
3. Polymerase chain reaction (PCR) is a technology that requires high temperatures to reproduce DNA fragments. Explain why the discovery of thermophilic archaea and their associated DNA polymerases was critical to the success of this technique.
4. Summarize how the electron transport chain functions to produce ATP in a bacterial cell versus eukaryotic cell. Explain whether or not the term chemiosmosis accurately illustrates this process.
Critical Thinking Sample:
Week 1 Critical Thinking
1. A microorganism is generally defined as an organism that we cannot see with the human eye, they are microscopic. To be considered a living organism, they must have the following traits: ability to respond to environmental stimuli, synthesize energy from their environment, and reproduction via DNA. For these reasons, I do not think that viruses are living microorganisms.
Viruses have the ability to survive and replicate only because of their environment. Without the presence of a host, the virus will lack the ability to reproduce and most of them will die quickly. To touch more on their ability to reproduce: in order to reproduce they utilize physiological mechanisms in the host. On their own, they do not have the required structures like a nucleus, organelles, or ribosomes. These are crucial “tools” for copying genes and creating offspring.
Another reason that viruses are non-living is because they cannot use energy or maintain homeostasis. As mentioned earlier, viruses lack nuclei and organelles which also make it possible for organisms to monitor or alter their internal environment. This also includes positive and negative feedback loops, which is what we rely on to maintain homeostasis. Some have made arguments that a virus’s capsule allows them to resist changes to their environment, but there needs to be continued research. As for energy consumption, there are some pretty major energy requirements for creating virion, but just like mentioned before, they get all this energy from the host.
Viruses are tricky in that they mimic a lot of mechanisms which other living organisms do. However, these actions come from the dependence and use of a host body. Without their host, they could not survive, reproduce, or utilize energy sources.
Are viruses dead or alive? (article) | Cells. (n.d.). Retrieved from https://www(dot)khanacademy(dot)org/test- prep/mcat/cells/viruses/a/are-viruses-dead-or-alive
Cowan, M. K. (2014). Microbiology: A Systems Approach. New York, NY: McGraw-Hill Higher Education.
2. Microbes have become an integral part of day to day human consumption. I will be exploring how we use microbes in food technology and medicine. One of my personal favorites is yogurt. Yogurt is essentially a fermented dairy produced with added flavoring and sometimes coloring to make it more appealing for consumers. It goes through a pretty detailed process, but it starts with heating the milk. We then add two bacteria: Streptoccocus thermophiles and Lactobacillus bulgaricus and allow it to grow and produce lactic acid. This process allows for the pH to become more basic, and inhibits the growth of microbes that could later spoil the product.
Another way that humans utilize microbes is through the creation of vaccinations for many diseases and illnesses. Vaccines are made from inactive or dead microbes, that are intentionally unable to cause disease. The antigen that is on the surface of the microbe is the exact same one in the vaccine. The vaccine is a way to kick start the body to produce antibodies against the antigen in the vaccine and microbe. Similar how the body uses muscle memory, your immune system will remember how it attacked the inactive microbe, it will remember the antibodies created and can in turn make them more efficiently this time and fight of the pathogen. This means that the person receiving the vaccine is now immune. If someone for some reason cannot receive a vaccine, then herd immunity becomes extremely important. Herd immunity happens when there are not enough people that can hold on to an infection, and there for cannot transmit the pathogen.
Lastly, are the microbes we get or give during childbirth. Babies that are born naturally and ones that are born via caesarean section have different microbes on their body and in their gut. Scientists have stated that it is very clear that birth “sets off a radical transformation of the infant gut” (Daweerdt). This is in fact an amazing event; colonization of a baby’s gut begins as soon as the baby comes into contact with microbes in the mother’s vaginal canal. They continue to contract more microbes when they breast feed, and finally from family members or pets athome. If a new born lacks these crucial steps, then there could be extreme consequences that can lead to death. Microbes are so important for the baby, because it allows for proper nutrient absorption and digestion.
6 great things microbes do for us. (2013, March 8). Retrieved from https://blog(dot)ted(dot)com/6-great-things-microbes- do-for-us/
Cowan, M. K. (2014). Microbiology: A Systems Approach. New York, NY: McGraw-Hill Higher Education.
Society, M. (n.d.). Vaccination. Retrieved from https://microbiologysociety(dot)org/why-microbiology-matters/what-is-
microbiology/microbes-and-the-human-body/vaccination.html
3. The five techniques used to manipulate, grow, examine, and categorize microorganisms are: inoculation, incubation, isolation, inspection, and identification. These are all time-tested procedures used to maintain and manipulate microorganisms with intentions of studying and recording. Inoculation is a process by which you introduce some microbe to an environment in which you know it will grow more. This has many purposes including increasing visibility, and testing vaccine effectiveness. Once inoculation has occurred within a specimen, it begins incubation. This is where the specimen is placed into a temperature-controlled incubator to increase multiplication of the microbe. During this time frame, the microbe produces more growth that is now macroscopically observable. Now we have entered the isolation phase. Isolation is the process of separating one species from another, once separated the microbe with have enough space to grow and create a mound of cells referred to as a colony. Finally, we have inspection and identification these processes allow us to properly categorize and identify the microbe that has gone through the other 5 I’s of culturing.
Cowan, M. K. (2014). Microbiology: A Systems Approach. New York, NY: McGraw-Hill Higher Education.
4. The three isolation techniques that I will review are: streak plate, pour plate, and spread plate. Using the streak plate technique, a small portion of the culture us spread across the surface using an inoculating loop. This spreading motion should thin out the sample and separate the cells. This method will not work if proper sterilization techniques are not followed. In the pour plate method, the culture is inoculated into a series of liquid agar tubes. This will dilute the number of cells in each tube. These tubes are then poured into sterile petri dishes and allowed to harden, this makes the cells even more wide spread and allows for more space to grow into more colonies. Lastly, is the spread plate technique which is where the diluted sample is pipetted on the surface of the medium i.e. agar plates and spread around using a tool. Pure cultures are most commonly used in laboratories it allows for more controlled exams of the microorganism.
Cowan, M. K. (2014). Microbiology: A Systems Approach. New York, NY: McGraw-Hill Higher Education.