Please write A Lab Paper about My Lab Project 2: Medical Mystery and please use the data that i recorded on my lab work to write my lab paper and follow the rubric and the directions that I posted here.
Name_____________________________________________________ Lab Project 2: Medical Mystery Characterize unknown bacteria to determine best treatment methods and identify the source of the bacteria using protist identification in creek samples. At the end of the lab project, you should be able to: · Define prokaryotic and eukaryotic · Distinguish prokaryotic cell shapes using appropriate terminology · Describe bacterial morphology and arrangement in a given slide · Determine whether a sample is Gram + or Gram - · Describe the process of creating bacterial lawns · Explain how antibiotic disks work · Predict the outcome of antibiotic treatment in bacterial populations · Predict the effects of selection on Zones of Inhibition · Determine antibiotic effectiveness for specific species based on Zones of Inhibition · Measure Zones of Inhibition · Describe how natural selection and antibiotic treatment lead to antibiotic resistance. · Compare and contrast the eukaryotic supergroups · Describe protist morphology and locomotion as identified with a microscope · Predict modes of nutrition based on cell structures · Identify and label distinguishing structures in protist cells · Utilize protist identification skills to determine matches between mixed protist samples Overview In part 1 of this lab, we will use microscopy to describe unknown bacteria and test the effectiveness of various antibiotics against the unknown bacteria. In part 2 of this lab, we will use microscopy to match protist populations of various samples in order to identify the source of the bacterial infection. Background of the case A backcountry camper has turned up at the hospital with an unknown bacterial infection, causing serious life-threatening symptoms. The camper did not treat or filter water from the creek he used during his wilderness trip, so one of the creeks in the area is a likely source of the bacterial infection. The unknown bacteria has been isolated from the camper’s stool samples, so the first priority is to try to identify the type of bacteria using morphology and Gram staining and to identify an effective antibiotic for treatment of his infection. The second priority is to identify the source of the water to prevent further spread of the disease. There are three creeks in the area near where the patient was camping. The patient does not remember which creek he collected water from; however, his water bottle still contains some water from the creek he drank from. Unfortunately, the bacteria is present is such low quantities in the water samples that it is not possible to look directly for the bacteria. Instead, we must compare the protist populations in the water bottle to those in the three suspected creeks to identify the source of the bacteria. Part 1 Characterizing an unknown bacteria Pre-lab to be completed at home before lab day Make sure you have read and completed this section in addition to reading the experiment description before the lab and the lab prep. Prokaryotic Cell Shapes Most prokaryotes are unicellular, although many species cluster together in colonies. Their size ranges from diameters of 1-5µm, while eukaryotic cells typically have diameters of 10-100µm. Prokaryotic cells come in a variety of shapes, but the three most common shapes are spherical (coccus), rod-shaped (bacillus), and helical (spirillum) (Figure 1). Cell shape and arrangement is characteristic of each species. Helical prokaryotes always occur as single cells, and bacilli and cocci may be connected in a variety of arrangements like pairs, chains or clusters. Figure 1. The most common shapes of prokaryotes. The Gram Stain While simple staining of prokaryotic cells shows us their morphology, it does not provide much of the information needed to identify specific species. The Gram staining method, named after the Danish bacteriologist Dr. Hans Christian Gram, is one of the most important staining techniques in microbiology. In the nineteenth century, Dr. Gram discovered a method for staining certain bacterial cells purple/blue, while staining eukaryotic and many other bacterial cells pink. Dr. Gram found that bacteria fell into two distinct categories when stained sequentially with crystal violet, followed in sequence by the following steps: 1) adding a mordant (reagent that fixes dye to cells) of iodine solution, 2) washing with a de-staining agent (ethanol or acetone; both are clear), and then 3) staining with safranin (a red counter-stain). One group of cells resisted removal of the crystal violet when washed with the de-staining agent, whereas the second group was readily decolorized by a brief rinse with the de-staining agent. The cells that resisted de-colorization remained deep purple or blue, and Dr. Gram called them gram-positive cells. The cells that were red after the complete staining procedure were called gram-negative cells. We now know that the staining differences among gram-positive and gram-negative bacteria are due to cell wall structure. Gram-positive bacteria have simpler cell walls than gram-negative species. Gram-positive bacteria have a cell wall with a large amount of peptidoglycan that traps the violet dye in the cell’s cytoplasm. Gram-negative bacteria have less peptidoglycan, and it is located in a layer between the cell membrane and an additional outer membrane. The violet dye is easily rinsed from the cytoplasm, and the cell appears red after the staining procedure (Figure 2). The gram characteristic is almost as fundamental to a bacterial description as its morphology. Figure 2. Gram-positive (left) and gram-negative bacteria (right). Gram staining is a particularly valuable identification tool used in medicine today. Among pathogenic bacteria, gram-negative species are generally more threatening than gram-positive species. The lipopolysaccharides on the walls of gram-negative bacteria are often toxic, and the additional outer membrane helps protect the bacteria from their host’s immune system. In addition, gram-negative bacteria are commonly more resistant to antibiotics; the outer membrane impedes drug entry. Selection and Antibiotic Resistance By definition, antibiotics kill living organisms (anti=against; bio=life). In the case of human usage, antibiotics are used to kill pathogenic bacteria or fungi by inhibiting enzyme-catalyzed processes necessary for the pathogen’s growth and survival. Many antibiotics are selective; they only work on a certain species of bacterium or fungus. While we often use the term “kill”; in fact, most antibiotics inhibit the reproduction of bacteria but do not actually kill existing cells. In recent years, we have seen a rise in antibiotic-resistant infections. When the antibiotic penicillin (derived from the soil fungus Penicillium) became widely available during World War II, it was a medical miracle. Penicillin was able to vanquish the biggest wartime killer, infected wounds. Just four years after drug companies began mass producing penicillin in 1943, resistant microbes began to appear. The first bacterium to resist penicillin was Staphylococcus aureus, also known simply as Staph. Antibiotic resistance can spread fast due to the ecology of bacteria. Bacteria have short generation times, and this facilitates a high rate of mutations (changes in nucleotide sequences). Therefore, the increased prevalence of antibiotic resistance is an outcome of evolution. Bacteria populations have variant genotypes, just like any other natural population, and some of those variants are going to resist the effects of antibiotics. Over time if the bacteria are routinely exposed to antibiotics, bacteria with resistance will survive and reproduce more and become more common in the population. In other words, natural selection will favor the resistant genotypes, and the population will eventually contain more antibiotic resistant individuals. As humans have increased the use of antibiotics, we create an environment that favors resistant bacteria. In addition, bacteria are capable of horizontal gene transfer, which allows bacteria to share genetic material with unrelated bacterial cells, which facilitates more rapid evolution of beneficial traits. Would there be resistant bacteria at all if antibiotics had never been discovered? If so, how would the prevalence of resistant bacteria be different if antibiotics had never been discovered? In order to administer antibiotics in experiments, we will use antibiotic disks placed on the agar plates. These disks release the antibiotic into the agar so that the concentration of antibiotic is very high near the disk but the concentration of antibiotic decreases further from the disk. Eventually, the concentration of antibiotic is so low that bacteria can grow. Thus, bacteria will grow in a ring around the disk. The area in which the bacteria cannot grow is called a Zone of Inhibition (Figure 3). The diameter of this zone can be measured and the relative size of the Zone of Inhibition is a good readout for how resistant to a particular antibiotic a bacterial species is. Figure 3. Zone of Inhibition In our experiment, you will be seeding a small number of bacteria and then letting them reproduce in the presence of antibiotic. If you placed an antibiotic disk on a lawn of bacteria that had already reproduced and filled the plate, would you see a zone of inhibition? Why or why not? I would say no because The Zone of inhibition is a round region around the spot of the anti-microbial in which the microscopic organisms provinces don't develop. The zone of hindrance can be utilized to quantify the vulnerability of the microbes to wards the anti-infection. The way toward estimating the distance across of this Zone of Inhibition can be computerized utilizing Image handling. In this work a calculation is created, utilizing Computer Vision, which will distinguish the zones of restraint of the microscopic organisms. This work exhibits a compelling methodology of estimating the Zone of Inhibition by ascertaining the sweep of the zone by illustration forms and setting the correct estimation of limit. This work additionally decides whether a specific microorganisms is defenseless or impervious to the connected anti-infection utilizing the determined Zone of Inhibition and the recommended standard qualities. If the resistant bacteria were transferred to new plates with antibiotic disks over and over again, there would be selective pressure for resistance. What would happen to the Zone of Inhibition if the bacteria became more resistant to the antibiotic over time? I think what would happen is Antimicrobial agents that drain out of the item and into the watery agar network, for example, silver particles, normally show preferred outcomes over antimicrobials that stay joined to the article or material or that are not water-soluble. Zone of Inhibition tests don't really demonstrate that microorganisms have been killed by an antimicrobial item - simply that they have been kept from growing. Microbial development agars themselves may meddle with the capacity of some antimicrobial agents. The strategy can't be utilized to test the action of antimicrobial operators against infections, since infections don't "develop" on agar plates like microscopic organisms infections don't imitate outside