Chapter 7 – Microbiology Answers – Flashcards
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| Nutrition |
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| process by which chemical substances (nutrients) are acquired from the environment and used in cellular activities |
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| Essential nutrients |
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| Essential nutrients must be provided to an organism; Two categories of essential nutrients: macronutrients, micronutrients (or trace elements) |
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| Macronutrients |
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| required in large quantities; play principal roles in cell structure and metabolism Proteins - nitrogen, carbohydrates - carbon |
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| Micronutrients (or trace elements) |
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| required in small amounts; involved in enzyme function and maintenance of protein structure; Manganese, zinc, nickel; nutrients |
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| Organic nutrients |
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| contain carbon and hydrogen atoms and are usually the products of living things; Methane (CH4), carbohydrates, lipids, proteins, and nucleic acids |
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| Inorganic nutrients |
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| atom or molecule that contains a combination of atoms other than carbon and hydrogen; Metals and their salts (magnesium sulfate, ferric nitrate, sodium phosphate), gases (oxygen, carbon dioxide) and water |
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| Chemical Analysis of Cell Contents |
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| 70% water; Proteins; 96% of cell is composed of 6 elements: Carbon, Hydrogen, Oxygen, Phosphorous, Sulfur, Nitrogen |
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| Heterotroph |
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| must obtain carbon from an organic form made by other living organisms; proteins, carbohydrates, lipids, and nucleic acids |
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| Autotroph |
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| uses CO2 (inorganic gas) as its carbon source; not nutritionally dependent on other living things |
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| Growth factors |
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| Organic compounds that cannot be synthesized by an organism because they lack the genetic and metabolic mechanisms to synthesize them; Growth factors must be provided as a nutrient; Essential amino acids, vitamins, nucleotides |
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| Nutritional types |
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| Main determinants of nutritional type are: Carbon source – heterotroph, autotroph;Energy source -Chemotroph – gain energy from chemical compounds;Phototrophs – gain energy through photosynthesis |
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| Photoautotrophs |
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| Oxygenic photosynthesis; Anoxygenic photosynthesis |
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| Chemoautotrophs |
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| lithoautotrophs survive totally on inorganic substances; methanogens, a kind of chemoautotroph, produce methane gas under anaerobic conditions |
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| Chemoheterotrophs |
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| Aerobic respiration; two categories: saprobes and parasites |
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| Saprobes |
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| free-living microorganisms that feed on organic detritus from dead organisms; Opportunistic pathogen; Facultative parasite |
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| Parasites |
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| derive nutrients from host; Pathogens; Some are obligate parasites |
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| Passive Transport |
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| does not require energy; substances exist in a gradient and move from areas of higher concentration toward areas of lower concentration; Diffusion; Osmosis – diffusion of water; Facilitated diffusion – requires a carrier |
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| Active Transport |
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| requires energy and carrier proteins; gradient independent; Active transport; Group translocation – transported molecule chemically altered; Bulk transport – endocytosis, exocytosis, pinocytosis |
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| Diffusion |
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| Net Movement of Molecules Down Their Concentration Gradient (Passive Transport) |
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| Osmosis |
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| Diffusion of Water (Passive Transport) |
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| Isotonic solution |
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| Water concentration is equal inside and outside of the cell, thus rates of diffusion are equal in both directions |
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| Hypotonic solution |
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| Net difussion of water is into the cell; Cell membrane: causes cell to swell and may burst if there is no mechanism to remove the water; Cell wall: swells the protoplast and pushes it tightly against the cell wall, preventing the cell from bursting |
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| Hypertonic solution |
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| Water difuses out of the cell; Cell membrane: causes it to shrink and become distoreted; cell wall: causes plasmolysis(shrinks the cell membrane away from the wall) |
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| Facilitated Diffusion |
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| Requires a carrier(Passive transport) |
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| Carrier-mediated active transport |
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| Atoms or molecules are transported into or out of the cell by specialized receptors, driven by ATP or other high energy molecules |
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| Group translocation |
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| transported molecule is chemically altered |
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| Endocytosis |
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| bringing substances into the cell through a vesicle or phagosome (bulk transport); Phagocytosis, pinocytosis |
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| Phagocytosis |
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| ingests substances or cells(bulk transport) |
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| Pinocytosis |
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| ingests liquids(bulk transport) |
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| Niche |
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| totality of adaptations organisms make to their habitat |
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| Environmental factors |
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| Environmental factors affect the function of metabolic enzymes; Factors include: Temperature, Oxygen requirements, pH, Osmotic pressure, Barometric pressure |
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| 3 Cardinal Temperatures |
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| Minimum temperature – lowest temperature that permits a microbe’s growth and metabolism; Maximum temperature – highest temperature that permits a microbe’s growth and metabolism; Optimum temperature – promotes the fastest rate of growth and metabolism |
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| 3 Temperature adaptation groups |
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| Psychrophiles, Mesophiles, Thermophiles |
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| Psychrophiles |
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| optimum temperature below 15oC; capable of growth at 0oC |
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| Mesophiles |
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| optimum temperature 20o-40oC; most human pathogens |
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| Thermophiles |
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| optimum temperature greater than 45oC |
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| Gas requirements |
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| Oxygen:As oxygen is utilized it is transformed into several toxic products: Singlet oxygen (1O2), superoxide ion (O2-), peroxide (H2O2), and hydroxyl radicals (OH-); Most cells have developed enzymes that neutralize these chemicals: Superoxide dismutase, catalase; If a microbe is not capable of dealing with toxic oxygen, it is forced to live in oxygen free habitats; Carbon dioxide: All microbes require some carbon dioxide in their metabolism |
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| Aerobe |
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| utilizes oxygen and can detoxify it |
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| Obligate aerobe |
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| cannot grow without oxygen |
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| Facultative anaaerobe |
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| utilizes oxygen but can also grow in its absence |
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| Microaeriphilic |
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| requires only a small amount of oxygen |
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| Anaerobe |
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| does not utilize oxygen |
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| Obligate anaerobe |
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| lacks the enzymes to detoxify oxygen so cannot survive in an oxygen environment |
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| Aerotolerant anaerobes |
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| do not utilize oxygen but can survive and grow in its presence |
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| Capnophile |
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| grows best at higher CO2 tensions than normally present in the atmosphere |
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| Neutrophiles |
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| Majority of microorganisms grow at a pH between 6 and 8 |
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| Acidophiles |
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| grow at extreme acid pH |
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| Alkalinophiles |
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| grow at extreme alkaline pH |
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| Barophiles |
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| can survive under extreme pressure and willl rupture if exposed to normal atmospheric pressure |
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| Symbiotic |
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| two organisms live together in a close partnership; mutualism, commensalism, parasitism |
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| Mutualism |
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| obligatory, dependent; both members benefit |
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| Commensalism |
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| commensal member benefits, other member neither harmed nor benefited |
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| Parasitism |
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| parasite is dependent and benefits; host is harmed |
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| Nonsymbiotic |
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| organisms are free-living; relationships not required for survival |
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| Synergism |
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| members cooperate to produce a result that none of them could do alone |
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| Antagonism |
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| actions of one organism affect the success or survival of others in the same community (competition), antibiosis |
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| Normal flora(microbes and humans) |
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| symbiotic bacteria, fungi, and a few protozoa |
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| Biofilms |
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| result when organisms attach to a substrate by some form of extracellular matrix that binds them together in complex organized layers; Dominate the structure of most natural environments on earth |
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| Quorum sensing |
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| Communicate and cooperate in the formation and function of biofilms |
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| Microbial growthoccurs at two levels: |
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| growth at a cellular level with increase in size, and increase in population |
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| Division of bacterial cells occurs mainly through: |
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| binary fission |
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| Binary fission |
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| Parent cell enlarges, duplicates its chromosome, and forms a central transverse septum dividing the cell into two daughter cells |
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| Generation or doubling time: |
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| Time required for a complete fission, can vary from minutes to days |
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| Exponential growth |
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| Each new fission cycle increases the population by a factor of 2 |
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| Growth curve |
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| In laboratory studies, populations typically display a predictable pattern over time |
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| Lag phase |
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| “flat” period of adjustment, enlargement; little growth |
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| Exponential growth phase |
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| a period of maximum growth will continue as long as cells have adequate nutrients and a favorable environment |
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| Stationary phase |
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| rate of cell growth equals rate of cell death caused by depleted nutrients and O2, excretion of organic acids and pollutants |
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| Death phase |
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| As limiting factors intensify, cells die exponentially |
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| Turbidometry |
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| method of analyzing population growth; most simple; degree of cloudiness, turbidity, reflects the relative population size |
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| Enumeration of bacteria |
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| method of analyzing population growth; Viable colony count; Direct cell count – count all cells present; automated or manual |
