chapter 7 microbial nutrition ecology & growth – Flashcards
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| Aerobe |
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| A microorganim that lives and grows in the presence of free gaseous oxygen (O2) |
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| Anaerobe |
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| A microorganism that grows best, or exclusively, in the absence of oxygen |
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| Binary Fision |
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| The formation of two new cells of approximately equal size as the result of parent cell division |
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| Commensalism |
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| An unequal relationship in which one species derives benefit without harming the other. |
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| Diffusion |
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| The dispersal of molecules, ions or microscopic particles propelled down a concentration gradient by spontandious random motion to achieve a uniform distribution. |
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| Essential nutrient |
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| Any ingredient such as a certain amino acid, fatty acid, vitamin or mineral that cannot be formed by an organism and must be supplied in the diet. A growth factor. |
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| Heterotroph |
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| An organism that relies on organic compounds for its carbon and energy needs. |
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| Lag phase |
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| the early phase of population growth during which no signs of growth occur |
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| normal microbial flora |
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| the native microbial forms that an individual harbors. |
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| nutrients |
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| any chemical substance that must be provided to a cell for normal metabolism and growth. Macronutrients are required in large amounts and micronutrients in small amounts. |
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| Obligate |
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| Without alternative; restricted to a particular characteristic. Ex: an obligate parasite survives and grows only in a host; an obligate aerobe must have O2 to grow; an obligate anaerobe is destroyed by O2. |
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| Opportunistic |
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| An infection, ordinarily nonpathenogenic or weakly pathogenic microbes, that causes disease primarily in immunologically compromised host. |
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| Parasite |
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| An organism that lives on or within another organism (host), from which it obtains nutrients and enjoys protection. Produces some degree of harm in the host. |
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| Pathogen |
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| Any agnet, usually a virus, bacterium, fungus, protozoan or helminth, that causes disease. |
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| Photoautotroph |
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| An organism that utilizes light for its energy and carbon dioxide mainly for its carbon needs. |
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| Saprobe |
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| A microbe that decomposes organic remains from dead organisms. Also known as a sprophyte or saprotroph. |
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| Symbiosis |
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| An intimate association between individuals from two species; used as a synonym for mutualism. |
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| What kind (mesophile, psychrophile, thermophile) of organism is typically associated with human disease? |
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| Mesophile (optimal growth/metabolism is from 20-40 degrees C) |
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| What kind (mesophile, psychrophile, thermophile) of organism is typically responsible for food poisoning? |
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| Psychrophile (optimal growth/metabolism is from 0-15 degrees C) |
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| What will happen to the growth of a thermophile adapted to 67 degrees C when it is grown at 55 degrees C? |
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| It will continue to grow/thrive because it's still in the optimum growth/metabolism range of 45-80 degrees C; 70 degrees C is ideal. |
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| Where does a capnophile live? |
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| In environments with a higher-than-normal concentration of carbon dioxide. |
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| Define autotroph |
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| Self-feeder; A microorganism that requires only inorganic nutrients and whose sole source of carbon is carbon dioxide. |
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| Define phototroph |
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| Microbes that use photosynthesis (sunlight) to feed; they derive their energy from sunlight & transform light rays into chemical energy. |
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| An organism adapted to saltwater is transported to a freshwater lake. Will osmosis cause it to shrink, swell or show no change? |
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| Swell. That's because water moves toward the higher solute concentrated areas ... this is a hypotonic situation. |
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| How does diffusion differ from active transport? |
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| Diffusion is the net movement of molecules from a high concentration area to a low-concentration area; there's no semi-permeable membrane; no energy is expanded. Active transport requires energy (ATP) |
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| How do the terms osmosis and chemiosmosis differ? |
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| Osmosis is diffusion of water through a permeable but selective membrane. Chemiosmosis is diffusion of a chemical other than water. |
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| How do amoebas drink? |
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| Pinocytosis. They engulf droplets of water to bring into the cell (active transport). |
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| What happens when a facultative anaerobe is placed in an oxygen-free environment? |
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| A facultative anaerobe adapts, uses anaerobic respiration or fermentation. |
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| What happens when an obligate anaerobe is placed in an oxygen-free environment? |
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| An obligate anaerobe will grow and metabolize in an oxygen-free environment because O2 isn't needed, and is in fact toxic to the cell. |
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| Coral reefs are a symbiotic relationship between and algae and a microscopic animal where both benefit ... what is this termed? |
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| Mutualism (rely on each other for growth) |
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| What kind of relationship exists between humans and Plasmodium? |
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| Parasitism (host/microbe relationship where the host is negatively impacted) |
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| During stationary phase, cells are dividing and dying at (constant, lagarithmic, flat or geometric) rates? |
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| Flat (equal) |
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| What is the definition of generation time? |
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| The time it takes for one cell to divide; The time required for a complete fission cycle - from parent cell to two new daughter cells. Also called doubling time. |
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| Describe three ways of determining the number of bacteria in a culture. |
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| 1. Turbidity: % of light transmitted through test-tube. the greater the turbidity, the larger the population size. 2. Direct cell count: count the total dead/live cells in special microscopic slide with a pre-measured grid. 3. Standard Plate Count: Start with unknown concentration of specimen; take mL and add to 99 mL of water; take 1 mL of that solution and add to 99 mL of water; repeat 2 more times; count the colonies in last solution when poured onto plate w/agar. |
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| Spring water has (more/fewer) water molecules than pure water or sea water? |
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| Fewer |
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| Sea water has (more/fewer) water molecules than pure water? |
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| Fewer |
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| What is the purest type of water? |
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| 18 Mega-ohm water |
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| Amoebas are in what Kingdom? |
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| Protista |
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| In osmosis, water moves from a ______ to a _____ concentration of water molecules. |
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| higher to lower |
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| The source of the necessary elements of life is... |
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| an inorganic environmental resevoir |
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| An organism that can synthesize all its required organic components from CO2 using energy from the sun is a ... |
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| Phtotoautotroph |
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| Chemoautotrophs can survive on ______ and ______ alone. |
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| minerals and CO2 |
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| All organisms require _____________ nutrients. |
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| inorganic |
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| A pathogen would most likely be described as: parasite, commensal, saprobe or symbiont? |
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| parasite |
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| Passive transport requires a __________. |
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| gradient |
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| A cell exposed to a hypertonic environment will _______ by osmosis. |
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| lose water |
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| Psychrophiles would be expected to grow __________________. |
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| at refrigerator temperatures |
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| Superoxide ion is toxic to strict anaerobes because they lack _____________. |
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| dismutase |
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| In a viable plate count, each ______ represents a _______ from the sample population. |
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| colony; cell |
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| An organic nutrient essential to an organism's metabolism is caled a ______ factor. |
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| growth |
