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Exam 2 Guide

by: Ally Lappe

Exam 2 Guide BSC 242

Ally Lappe
GPA 3.93

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This 13 page Study Guide was uploaded by Ally Lappe on Wednesday March 25, 2015. The Study Guide belongs to BSC 242 at University of Alabama - Tuscaloosa taught by Gray in Fall. Since its upload, it has received 60 views. For similar materials see Microbiology in Biology at University of Alabama - Tuscaloosa.


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Date Created: 03/25/15
Chapter 6 1 Classify microbes into 5 groups on the basis of preferred temperature range Cold to Hot Psychrophiles psychrotrophs mesophiles thermophiles hyperthermophiles 2 Discuss the importance of pH of culture media An optimum pH is needed for bacterium to grow pH can be manipulated to grow most bacterium 65 75 or to favor certain types such as yeasts and molds 5 6 Acidophiles favor acidic conditions and can survive in a pH as low as 1 These grow on organisms such as citrus fruits and make you very sick 3 Explain the importance of osmotic pressure on microbial growth An optimum osmotic pressure for the cell is necessary because if the surrounding solution is too salty the cell will lose water and lysis In contrast if the surrounding solution is pure water water will rush into the cell causing it to burst Different types of cells require different osmotic pressures Ex Halophiles desire high salt concentration and can either be obligate dead sea bacterium or facultative staphylococci 4 Why do cells need Carbon Nitrogen Sulfur Phosphorus and Trace Elements Provide examples for the use of each Carbon is necessary for energy and makes up 50 of a living organism sugars respiration etc Nitrogen is a part of amino acids proteins and nucleic acids and makes up about 14 of an organism NH4 or N03 but cyanobacterium can nitrogen fix with N2 Sulfur is in amino acids cysteine thiamine and biotin Most organisms decompose proteins but some use 804 or H28 Phosphorous is in DNA RNA ATP and membranes P04 Trace Elements are inorganic elements needed in small amounts that are used as enzyme cofactors Zinc iron and magnesium 5Describe the classes of microbes based on oxygen requirements Obligate anaerobes require 02 to grow and will always be found at the top of a test tube Facultative anaerobes prefer to be away from 02 but if it is present they will use it and are typically found throughout but mostly at the top Obligate anaerobes cannot replicate in the presence of oxygen and will always be found on the bottom of a tube Aerotolerant anaerobes grow evenly and are found all over the tube Microaerophiles require a very specific amount of oxygen and will grow only somewhere in the middle of the tube 6What are the roles of superoxide dismutase catalase and peroxidase Superoxide dismutase converts oxygen and hydrogen into hydrogen peroxide and oxygen Catalase converts hydrogen peroxide into water and oxygen human cells Peroxidase converts hydrogen peroxide and oxygen into water molecules These are all toxic forms of oxygen 7 Distinguish between chemically defined and complex media A chemically defined media is typically used for research and has listed exact molecules and amounts of each ingredient Complex medias are more general and consist mainly of animal extracts and proteins nutrient brothagar 8When would you need reducing media You would need reducing media when trying to grow anaerobic bacterium Reducing media contains chemicals such as thioglycollate or oxyrase which combine 02 and eliminate it 9Describe the use of selective media and differential media Selective media is used when only a specific bacteria is desired to grow It makes conditions favorable for only those species desired Ex antibiotics in agar Sabourad s Dextrose Agar low pH to favor yeasts or bismuth sulfate inhibits and most except for Salmonella typhi Differential media grows everything but different types of cells will appear differently once cultured EX blood agar is used to identify species that rupture RBCs such as streptococcus X gal plates show lactose positive colonies as blue and negatives as white Selective and Differential media includes mannitol salts agar which uses high salt concentration to select for S aureus while its pH indicator turns fermenters of mannitol a specific color Eosin Methylene Blue selects by dyes which inhibit bacterium and differentiates my lactose fermenters turning a dark color E coli turns a metallic green under EMB meaning it metabolized lactose into an acid 10Why is agar used and What makes it a good choice Agar is used as a solidifying agent for a nutrient suspension This allows us to determine aerobicanaerobic qualities of bacterium Agar is a good choice because it is solid at room temperature and it liquefies at a temperature which sterilizes it Agar is also not metabolized by the microbes within the suspension 11Define colony A colony is a group of same species bacteria that arose from a single parent cell A coliform is a colony as a result of sugar fermentation lactose 12 What is Binary Fission What is Generation Time Binary fission is the main process of growth for bacteria The cell simply grows and splits into two free living organisms Generation time is the time it takes for a colony to double in number or for one cell to split into two identical cells E coli generation time is 20 minutes Yeasts split by budding not binary fission 13 What are the characteristics of each stage in the growth of a culture Lag phase is a growth stage where enzymes are produced Log or eXponential growth follows once optimum conditions are met Stationary phase occurs when nutrients begin to run out and toxicity builds and as many cells die as are being made Death stage occurs when the environment is no longer conducive due to buildup of wastes and cells begin to die 14Discuss the different ways to measure the growth of cells directly and indirectly Directly through plate counts filtration coliforms in water MPN or direct microscope count MPN is most probable number and uses a multiple test tubes and a comparison chart Indirectly through turbidity metablic activity and dry weight 15 Calculate the cellsml of a culture using a plate count method Only viable if 25 250 colonies present any more and dilution was not extensive enough Chapter 7 1Define the following terms related to microbial control sterilization commercial sterilization disinfection antisepsis degerming sanitization cidal static Sterilization kills all microbials present Commerical sterilization is used to kill mirobes to a certain public health standard death of Clostridium botulinum endospores Disinfection is the removal of pathogens from surfaces Antisepsis is the removal of pathogens from living tissues Degerming removes pathogens from a limited area Sanitization lowers counts to a public health standard level A germicidal cidal kills microorganisms and a bacteriostasis statis inhibits but does not kill microorganisms 2 What are the general factors that in uence the rate of microbial death Number of microbes environment organic matter temperature biofilms time of exposure and microbial characteristics 3 Define and compare the effectiveness of moist heat boiling autoclaving pasteurizations and dry heat methods of control When would you use each of these Moist heat coagulates and denatures proteins Dry heat kills by oxidation effects aming incineration or hot air sterilization 4When is Filtration the method of choice and basically how does it work Radiation Filtration is often used in burn units to filter out large pathogens Ionizing Radiation kills microbes in food mail and medical supplies by Xray and gamma radiation Nonionizing Radiation treats some vaccines and a lamp of UV light is used in burn units Radiation damages DNA by causing a mispairing of bases 5 Describe how low temperature high temperature desiccation and osmotic pressure suppress microbial growth Low and high temperatures are used to make environments less favorable and halt metabolic activity enzymes Desiccation is the removal of 02 which prevents metabolism Osmotic pressure is the most controlled of these and causes plasmolysis 6 What are the general groups of chemical control agents Provide common examples of each Examples How Effective Ineffective Extra Phenols LysolAmphyll Membrane mycobacteria Active in organic and compounds pus proteins saliva Bisphenols HexachloropheneTriclosa Plasma Staph strep Resistant Triclosan in 11 membrane and yeast strains found antibacterial soap Biguanides Chlorhexidine Cell Skin and Surgical scrubs membranes mucous membranes Halogens IodineChlorine Betadine Enzyme Mycobacteria Used in water or Clorox activity and treatment endospores Heavy Metals Ag Hg Cu silver nitrate Denature Huge effect Catheters surfacine proteins molds in mercurochrome in eyes comb roofs of babies With sulfhydryl Alcohols Ethanol Isopropanol Denatures Bacteria and Endospores Used to degerm but proteins fungi or can enhance other dissolves nonenvelope agents lipids d viruses Surfactants Soaps or detergents Decrease Lifts debris Degerming agent only surface tension Organic Acids Sorbic or benzoic acid inhibiting Molds in Possible Nitrite prevents calcium propionate metabolism foodcosmetic carcinogen endospores in meat s botulism too Antibiotics Nisin natamycin Inhibit cheeses endospores antifungal Aldehydes Glutaraldehyde Inactivate Endospores VERY good against formaldehyde proteins by and tuberculosis leprosy orthophthaldehyde cross mycobacteria pneumonia linking Gaseous Ethylene oxide Denatures All microbes Toxic and Penetrates well and proteins and explosive replaces H with a endospores radical version QUATS sufactants membranes less on No mycobacteria or endospores Peroxygens Ozone H202 benzoyl Oxidizing Not very Catalase in humans peroxide paracetic acid agents effective at inactivates h202 all 7 Describe the DiskDiffusion method of evaluating a disinfectant Filter paper is soaked with disinfectant and placed on a cultured plate Cleared area is the zone of inhibition 8Why do different classes of organisms respond differently to biocides especially with respect to Grampositives Gramnegatives Mycobacteria and Endosporeformers Put these in the order of most resistant to least resistant Most to least endospores mycobacteria gram gram Chapter 27 1 Define extremophile and identify two quotextremequot habitats Extremophiles are typically archaebacterium They prefer extremes such as acidophiles low pH halophiles high salinity hyperthermophiles high heat 2 Define symbiosis saprophytes and bioremediation In symbiosis two organisms help eachother with their metabol ic cycles and require the other to survive Saprophytes feed on dead organisms Bioremediation is the recycling through redox reactions of chemical elements by mircobes De ne biogeochemical cycle A biogeochemical cycle is one in which elements are oxidized by microorganisms to meet their metabolic needs and reduced Outline the basic carbon cycle and explain the roles of microorganisms in this cycle 002 in atmosphere Burning Plants algae cyanobacteria Animal respiration a respiration ll EIEIEIIIEIEIEI unuunuu Wood and fossil Nels nimalsi 7 Dissolved 002 Dead I 39 39 organisms tic bacteria cyanobaoteria hotynthesi Plants algae 539 Orgnisms u als dmg aquati G 5 Outline the basic nitrogen cycle and explain the roles of microorganisms in this cycle f Free nitrogen gas N2 in atmosphere Nensymbiotic protein Legumlnuus Azambacter Industrial from plants Beije nckfa fixation as dead ceils kn cyanobacteria fertilizer 39 quot Closiridium ecay organisms 3j aerobic and 39 I 393939anaerobic bacteriai39 Symbio c 39 quot39 39 39 1 39 andfun i 39 Denitriiying bacteria 39 i 9 i B Hg z l mgl Pseudamonas 39 l m y F0 quoti Bacillusiieheniformis Iv 39 39quot 39L 39 quot 39 39 quot Paracoccus denitri cans and others Almhidniticeiiehl Narifreeing 39 39 39l 39 nitrifie39 tibnr 1 Ammonification removal of amino groups from amino acids deamination by bacteria and fungi decay organisms as well as symbiotic rhizobium They convert unusable form into ammonia NH3 Nitrification production of nitrate by oxidizing nitrogen from ammonia Nitrosomas convert to nitrite nitrobacter to nitrates Denitrification loss of N2 to atmosphere as well as plants in low 02 soils by pseudomonas N03 nitrate converted to N2 Nitrogen Fixation N2 gas is converted to ammonia by legumes and cyanobacteria and put back into soil Nitrogenase enzyme needed to fix N2 as well as heterocysts which provide anaerobic conditions for fixation De ne ammoni cation nitri cation denitrification and nitrogen fixation see above 7 Outline the basic sulfur cycle and explain the roles of microorganisms in this cycle Aerobic conditions I Elemental I 7 3 lquot 177 i7 5 Beggiatoa Microbial quot r a Thiobac NUS oxidation r i In 1 fork Assimilation quot r y by pianisaaand Sll sulfhydrV39 Ezoiecompos39itinn groups of 39 quot 7 proteins I3 2 39 39039 1 39quot 39 Ils iiat97rvff 2quotPhafoiro i baet a 39 75f 1 Lquot 39 e 391 L 39 39 Purple d39g r e n iv mosi39i i Soilands dimeht Ei meniolsulfur 39 39 quot quot 39 39 The sulfur cycle is similar to the nitrogen cycle because it undergoes many oxidations Phototrophic bacteria green and purple convert reduced sulfur H28 into elemental sulfur granules and fully oxidized 804 is used for energy Plants and bacteria make sulfur containing amino acids for humans and animals Then dissimulation decomposes proteins and sulfur is re released as H28 Thipbacillus can use H28 as an energy source Without oxidizing it Elemental sulfur is released by dying microbes and accumulates underground in sediments and is not easily reabsorbed Describe how an ecological community can exist Without light energy By exploiting H28 in deep sea vents and caves Autotrophic endolithic bacteria split H20 and use the radioactive hydrogen as energy CO2 in water is its carbon source 9 Describe the basic phosphorus cycle It is very unlike the other cycles because it exists mainly as P04 and undergoes little change It is not oxidized or reduced but changes from soluble to insoluble and organic to inorganic in relation to pH In addition there are no phosphorous products to return to the atmosphere like in the other cycles The P accumulates in the seas and must be mined or ingested by way of sea birds eating P containing fish Plants can also absorb phosphates 10 Give an example of the use of bacteria to remove pollutants Bioremediation is whee microbes detox or degrade pollutants such as in the BP oil spill Bioaugmentation is the addition of specific microbes to metabolize a certain pollutant Composting is an example of microbe degredation of pollutants Xenophiles such as plastic and Styrofoam do not degrade 11 Describe the general characteristics of biofilms and how these are a special concern in hospitals Biofilms form wherever liquid meets a solid surface and are composed of many different species that act symbiotically They form a coordinated community with one brain and DNA exchange to more easily resist biocides 12 Explain how water is tested for bacteriological quality Water is tested by most probably number MPN membrane filter technique and ONPGMUG fecal glows and coliforns yellow tests for coliforns Coliforns are aerobic or facultatively anaerobic gram negative nonendospore forming rods that ferment lactose to acid 13 Describe how pathogens are removed from drinking water Water is held in a reservoir for sedimentation pumped into a mixing tank with occulant aluminum potassium sulfate oc is created by agglunation and settles water is filtered then disinfected by chlorination ozone or UV light 14 Compare primary secondary and tertiary sewage treatment Primary physical occurs near the home as sewage is screened skimmed and group as large solids settle out In secondary microbial the sweage is aerated as microorganisms oxidize organic matter In tertiary chemical the ef uent is disinfected by chlorination and released into a lake or reservoir 15 What the major biochemical activities that take place in an anaerobic sludge digester are The digester encourages anaerobic cell growth These cells then degrade the organic substances to methane gas and carbon dioxide 1 C02 and organic acids formed from anaerobic fermentation by microorganisms 2 Organic acids are metabolized to form hydrogen and carbon dioxide as well as organic acids such as acetic acid 3 Methane producing bacteria produce methane and water from carbon dioxide and hydrogen 16 De ne activated sludge system trickling filter septic tank An Activated Sludge System is one in which the aeration tank airates with oc then the efferent settles to be taken out settles sludge A Trickling Filter is another secondary treatment where sewage is sprayed over rocks and biofilms oxidize much of the organic matter but are less effective than activated sludge systems In a primary treatment Septic Tank sewage enters a holding tank and the suspended solids settle out must be pumped periodically Chapter 28 1 Describe the different types of spoilage of canned goods by microorganisms Thermophillic anaerobic spoilageoccurs when thermophiles survive canning in low acid foods The can swells and the contents have a low pH and a sour odor Clostridium Flat sour spoilage is when thermophillic spoilage occurs without gas production or swelling Mesophillic bacteria can spoil if the food is unprocessed or if the can leaks 2 Describe the following methods to preserve foods canning commercial sterilization aseptic packaging radiation plasmolysis fermentation Commercial Sterilization CanningL steam under pressure in a large retort autoclave to destroy botulinum endospores Aseptic Packaging packages are made of some material that cannot tolerate conventional heat treatment and are sterilized in a roll with hot H202 solution or by UV light Radiation meats are hit by gamma rays to destroy endospores Plasmolysis call ruptures Fermentation sugar to acid used in wine 3 Describe some beneficial activities of microorganisms in food production especially Wines yogurt and cheeses Beer and ale are fermented by yeasts Yogurt is streptococcus thermophilis and lactobacillus Blue cheese is penicillin The curd is casein formed by rennin and is aided by lactic acid producing bacteria


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