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BIOLOGY 204 GENERAL MICROBIOLOGY INSTRUCTOR: Dr A. Hemsley ANTELOPE VALLEY COLLEGE SPRING 2005 THEORY TEST 2 100 POINTS STUDENT NAME: ___________________________________ STUDENT I.D. NUMBER: _____________________________ • • • • • • • Perusal time = 10 minutes Test time = 105 minutes ANSWER ALL QUESTIONS Read ALL questions carefully during perusal time, you may write if you wish. Use the back of each sheet if you do not have enough writing space, but please label each answer. Question subheadings are NOT of equal points value. Points allocated for each subheading are shown at the end of the question. GOOD LUCK! QUESTION 1 (Total =10 points) Match entries in the left column with answers from the lettered choices in the right column. Write your letter choice to the far left of each question in the spaces provided. Use each answer only ONCE. (1 Point per correct pair) _____ 1. Moist heat treatment that will disinfect a. Ultra-high temperature _____ 2. Moist heat treatment that will sterilize b. Boiling _____ 3. Milk pasteurization for 1 second at 140oC c. Bacteriostasis _____ 4. Milk pasteurization for 15 seconds at 72oC d. Fungicide _____ 5.Disinfectant safe to use of living tissue e. Sanitization _____ 6. Prevention of bacterial growth without killing the bacteria present f. Pasteurization _____ 7. Instrument using dry heat to sterilize g. High temperature Short time _____8. Reduction of pathogen counts on eating and drinking utensils to safe public health levels h. Oven _____ 9. Agent capable of killing fungi _____ 10. Method of heat treatment designed to kill vegetative pathogens i Antiseptic j. Autoclaving Page 1 QUESTION 2 (Total =10 points) The following growth patterns were found when Cultures A, B, C, D and E were placed in thioglycollate broth tubes and grown in an incubator overnight without any shaking. A B C D E See Table 6.1 for the growth patterns that should be in the tubes. With respect to its oxygen preference, describe each of the above cultures and explain the growth pattern seen A. B. C. D. E. Page 2 QUESTION 3 (Total =20 points) A. Provide two reasons why the structure of quarternary ammonium detergents permits them to be effective disruptors of plasma membranes. (4) B. Fill In the blanks in the following table: Name of disinfectant Mechanism of action or antiseptic ____________(Oxidizer) Oxidizer of membranes/proteins Denatures lipid membranes Iodine (Halogen) (12) Advantages Unstable on tissues Adheres to skin/mucus membranes Extensive use In water disinfection and sewage treatment Ethanol Phenolics C. Disadvantages Unpalatable for water disinfection Unstable over long times In aqueous solution Can cause drying of wounds Carcinogen List four principles that we need to consider when choosing an appropriate disinfection protocol. Explain, with an example for each one, how each principle can Influence the success of the disinfection process. (4) Page 3 QUESTION 4 (Total =20 points) A. B. Explain why It Is essential for a species to have a large gene pool, and describe one strategy used by eukaryotes and one used by prokaryotes to generate a large gene pool. (6) Give description of the roles of each of the following RNA molecules within the microbial cell (6) messenger RNA ribosomal RNA transfer RNA C. Describe what is meant by GENOTYPE and PHENOTYPE and give an example of each (4) D. Explain why It Is sometimes possible for microbes with different genotypes to display the same phenotype. (4) Page 4 QUESTION 5 (Total =20 points) Fill in the blanks in the following sentences. (1 point per correct sentence) 1. The nucleotide that pairs with G in RNA is____________________________. 2. The first codon in all mRNA molecules is____________________________. 3. One of the three codon sequences that signal protein synthesis termination is ____________________________. 4. A microbial test commonly performed to detect carcinogens is the ____________________________. 5. One chemical agent capable of causing mutations is ____________________________. 6. A DNA mutation where a base change does not affect the protein sequence of the gene product is called a ____________________________ mutation. 7. A DNA mutation where a base change affects one amino acid in the protein sequence of the gene product is called a ____________________________ mutation. 8. A DNA mutation where a base change introduces a STOP codon in the protein sequence of the gene product is called a ____________________________ mutation. 9. A ___________________________ microbe is one that is metabolically active. 10. ____________________________is a mechanism that introduces new genetic material into a bacterium as naked DNA. 11. ____________________________ is a mechanism that introduces new genetic material into a bacterium by way of a bacteriophage vector. 12. ____________________________ is a mechanism that introduces new genetic material into a bacterium due to a mating event initiated by the F plasmid. 13. Plasmids confer a survival advantage, such as____________________________ to bacteria possessing them. 14. ____________________________ is an enzyme that catalyses the formation of an RNA chain. 15. The ____________________________ is an enzyme used to cut DNA at specific sequences. 16. One important recombinant gene product expressed in bacteria is____________________________. 17. A method of artificially introducing genes into cells is ____________________________ . 18. The _________________ ________________________ amounts of DNA from a small initial sample. 19. ____________________________ is a process that uses microbes to clean up chemical spills or pollution created by humans within the natural environment. 20. One agricultural application of genetic engineering is Improvement In the_____________________________ of crops. ____________________ is a technique for creating large Page 5 QUESTION 6 (Total =20 points) A. The polymerase chain reaction (PCR) is a technique that may be used diagnostically to determine HIV status in individuals who have engaged in high-risk behaviors. The technique is more costly than other detection methods. What is an important advantage of using this detection method? (5) B. Describe the steps involved in PCR C. PCR uses a DNA polymerase that comes from a thermophilic bacterium Thermus aquaticus, not from our favorite laboratory pet, Escherichia coli. Explain why this Is so. (5) D. The enzyme DNA Ligase is not needed In PCR. Explain why this is so. (5) (5) Page 6