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BioSc221/325 Exam 1 Name ______________________________ Multiple choice. (2 point each) Choose the one best answer to each of the following questions. ____ Fossilized stromatolites, which provide a geological record of early microorganisms, were formed from A. B. C. D. layers of decayed marine animals that were degraded by microorganisms layers of decayed marine plants that were degraded by microorganisms microbial mats, layers of microbial communities chemicals that formed during the early earth that came together to form the first microorganisms ____ In general, prokaryotic cells are __. A. B. C. D. larger than eukaryotic cells smaller than eukaryotic cells about the same size a eukaryotic cells not physiologically comparable to eukaryotic cells and therefore proaryotic and eukaryotic cell sizes should not be compared. ____ The three domains of life are prokaryotes, eukaryotes, eubacteria protists, plants, animals plants, animals, monera bacteria, archaea, eukarya ____ Enzyme found in tears that cleaves the -1,4 linkage of the peptidoglycan layer. A. B. C. D. lysozyme murein penicillin vancomycin ____ Bacteriophage lambda has provided a wealth of information for biologists interested in how microorganisms make “decisions” because lambda “decides” between infecting Escherichia coli or Salmonella typhimurium a lytic or lysogenic life cycle lysing its host cell or budding from the host cell membrane forming a plaque or a colony _____ Antiviral drug therapy ideally should target viral activities that are unique to the virus. One of these targets is the process or attachment. A fairly new anti-influenza drug targets _____ a protein on the surface of the influenza virus which is associated with the attachment process. A. B. C. D. influenza capsomer protein pilin neuraminidase porin ____ An organism requiring many growth factors and only grows on a complex medium is described as A. B. C. D. finicky selective facultative fastidious ____Archaea acquired their name because they were thought to be ancient in the fact that they resemble some of the earliest microorganisms. That is because these organisms live in ___ conditions which resemble the conditions on early earth. A. B. C. D. E. anoxic high temperature high saline All of the above None of the above ____ A bacterial cell which has lost its peptidoglycan layer but remains intact is called a(n) A. B. C. D. lysozome protoplast periplasm osmoplast ____ Proteins that form channels in the outer membranes of gram-negative bacteria. A. B. C. D. bactoprenols lipoproteins porins transport proteins ____ Attachment is an essential step for pathogenic bacteria to infect their host. Many bacteria have long filamentous protein structures that aid in this process. These structures are called A. B. C. D. porins pili receptors teichoic acids ____ AZT is an antiviral drug used to treat patients with HIV infections. Although this nucleotide analog can also be harmful to the host cell machinery it is effective because _____, an enzyme that is unique to HIV, preferentially tries to use AZT over the normal nucleotides. A. B. C. D. reverse transcriptase DNA polymerase RNA polymerase ligase ____ Molecules found in halophiles that protect them from the low water activity of their environment. A. B. C. D. compatible solutes halites halogens isotoners ____ Microscopes that are designed to enhance the contrast between cells and their surrounding medium are called A. B. C. D. bright field dark-field phase contrast epifluorescent ____ Methanogenic archaea are prokaryotic organisms that are found in anoxic conditions and only use molecules with one carbon as their carbon source. Which of the following describes the conditions for an enrichment culture for methanogenic archaea from the human colon? A. B. C. D. Carbon dioxide, hydrogen, oxygen free Carbon dioxide, oxygen rich Glucose, oxygen free Glucose, oxygen rich ____ Lipopolysaccharide (LPS) is associated with __ . A. B. C. D. the outer membrane of Gram-positive bacteria. the outer membrane of Gram-negative bacteria. the cytoplasmic membrane of Gram-positive bacteria. the cytoplasmic membrane of Gram-negative bacteria. ____ The objective lenses of modern light microscopes are described as compound lenses because they consist of several lenses of different shapes (convex or concave) and different glass. The purpose of these compound lenses is to A. B. C. D. correct spherical and chromatic aberrations increase resolving power extend the length of the lens to get closer to the sample to match the optical properties of the microscope slide, coverslip and immersion oil ____ Form of oxygen that is toxic to living organisms A. B. C. D. E. hydrogen peroxide singlet oxygen superoxide none of the above all of the above ____ Electron microscopes are used to visual bacterial subcellular structures. The ability to resolve such small structures is achieved through the short wavelength of electrons the ability to get the lenses of the electron microscope very close to the sample that high intensity of the electron beam all of the above none of the above ____ When doing a colony count __. A. B. C. D. It is assumed that each colony arose from only one organism. Only viable cells are counted The medium must be suitable for colonial growth All of the above ____ The bacterial “cannibal” Bdevolovibrio bacteriovorans” moves toward its prey by responding to chemical signals.. This type of movement is described as A. B. C. D. random walk brownian motion chemiosmosis chemotaxis ____ Enveloped viruses exit their host cell by a process called A. B. C. D. lysis lysogeny extraction budding Matching. (1 point each) Match the definition in the left column with the appropriate term in the right column. Note, not all terms will be used. ____ Molecule found in the cell wall of Gram-positive but not Gram-negative bacteria. ____ Associated child-bed fever with medical students not washing their hands after surgery. ____ The first to use an epidemiological approach to solving a disease outbreak (cholera). ____ Identified the causative agents of the deadly diseases anthrax and tuberculosis ____ Cocci arranged in "grape-like" clusters. ____ A culture technique in which conditions favor the growth of the desired type of organism. ____ A device for enumerating microorganisms by microscope instead of cultivation. ____ Bacteria that remain blue after completion of the Gram stain procedure. ____ Technique that makes it possible to separate large genome size DNA fragments on a gel. A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R. Enrichment Gram-negative Gram-positive Koch, Robert Lipoteichoic acid Murein N-acetylmuramic acid N-acetyltalosaminuronic acid Pasteur, Louis Peptidoglycan Petroff-Hauser counter Pseudopeptidoglycan Pulsed-field Gel Electrophoresis Sarcina Semmelweis, Ignaz Snow, John Staphylococci Streptococci Short answer. (1 point each) Penicillin can kill bacteria because it interferes with ______________________. A bacterium that has an optimal growth temperature of 37 oC but still grows at 4oC is described as ______________________. A bacterium that has an optimal growth temperature of 30 oC would be described as a ___________________________. An organism that requires a pH of 9.5 for optimal growth would be called a(n)___________________________. Thiomargarita namibiensis is the largest known prokaryote (actually visible without a microscope). Briefly explain why large prokaryotes are rare. Give one reason why microbiologists have failed to cultivate many of the microbes in the environment. Poliovirus is an enterovirus that primarily infects the cells of the gastrointestinal tract. In general terms, what is responsible for this specificity? The diagram below illustrates a series of dilutions of a culture of Escherichia coli. One tenth of a milliliter (0.1 mL) of each dilution is plated on an agar medium that supports the growth of E. coli. The number in each circle represents the number of colonies observed on each plate. Calculate the number of viable bacterial cells in one milliliter of the original sample. Describe two features that distinguish prokaryotes from eukaryotes. Myxococcus xanthus exhibits gliding motility. Name one other type of motility that bacteria can use. Short Essay Questions. Please answer 3 of the following 4 short essay questions (5 points each - 5 bonus points possible for answering all 4 questions) Describe the structure of the outer membrane of a Gram-negative bacterium in as much detail as possible. Include a description of any key components of the outer membrane. A labeled picture is OK. Describe the steps in the Gram stain, including what is happening to the organisms being stained at each step and how the stain differentiates Gram positive from Gram negative cells. List four different methods for counting cells/measuring cell growth. Briefly describe each method and briefly explain the advantages and disadvantages of each. Briefly describe the 4 steps in the viral infection process.