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Micro ch7 Growth, et
| Question | Answer |
|---|---|
| Nutrition | process by which chemical substances called nutrients are acquired from the environment and used in cellular activities such as metabolism and growth. |
| Essential nutrient | substance whether in elemental or molecular form, that must be provided to an organism |
| Macronutrients | category of essential nutrient ; required in relatively large quantities and play principal roles in cell strcuture and metabolism |
| Micronutrients or “trace elements” | category of essential nutrient ; present in much smaller amoutns and are involved in enzyme function and maintenance of protein structure |
| Chemical analysis of microbial cytoplasm | chemical composition can indicate cell nutritional requirements; Water (70%); Proteins are next most prevalent |
| Organic compounds | about 97% of dry cell weight |
| Chemical elements | about 96% of cell is composed of six elements (CHONPS); needed in the overall scheme of cell growth, but most are available to cell as compounds and not pure elements |
| Heterotroph | organism that obtains carbon in organic form ; since organic carbon originates from bodies of other organisms, dependent on other life forms. Things that meet carbon requirements - proteins, carbs, lipids, nucelic acids |
| Autotroph | « self-feeder » ; organism that uses inorganic CO2 as its carbon source ; have special capacity to convert CO2 into organic compounds, so not nutrionally dependent on other living things. |
| Nitrogen sources | main reservoir is nitrogen gas (N2) ; indispensable to structure of proteins, DNA, RNA, ATP ; primary nitrogen source for heterotrophs, but only after they are degraded into their basic building blocks |
| Oxygen sources | common component of inorganic salts (sulfates, phosphates, nitrates, water) ; free gaseous O2 is available in atmosphere ; essential to metabolism |
| Hydrogen sources | major element in all organic and several inorganic compounds, including water, salts, and certain natural gases. |
| Hydrogen source Performs 3 overlapping roles | Maintain pH, Form hydrogen bonds between molecules, Serve as source of free energy in oxidation-reduction reactions |
| Phosphorus (phosphate) sources | main source is phosphate (PO43-) ; found in rocks and oceanic mineral deposits ; key component of nucleic acids, so essential to genetic of cells/viruses. Also found in ATP, so serves in cellular energy transfers |
| Sulfur sources | widely distributed throughout the environment in mineral form |
| Other nutrients important in microbial metabolism | mineral ions (potassium, sodium, calcium, magnesium, iron, zinc, etc) |
| Growth factors | Esstl organic nutrients; organic compounds that can't be synthesized by an organism Include amino acids, a nitrogenous base, or a vitamin that cannot be synthesized by an organism. |
| Phototrophs | microbes that photosynthesize |
| Chemotrophs | microbes that gain energy from chemical compounds. |
| Photoautotrophs | photosynthetic—capture energy of light rays, transform it into chemical energy used in cell metabolism. Form basis of most food webs since produce organic molecules that can be used by other organisms and by themselves. Ex. Plants, algae, some bacteria |
| Chemoautotrophs | two types—chemoorganic, which use organic compounds for energy and inorganic compounds as carbon source, and lithoautotrophs, which requires neither sunlight nor organic nutrients, relying totally on inorganic materials. |
| Methanogens | chemoautotrophs; produce methane from hydrogen gas and carbon dioxide. |
| Chemoheterotrophs | majority of heterotrophic organisms; derive both carbon and energy from organic compounds. Processing by respiration or fermentation releases ATP; two categories depending on how they obtain their organic nutrients |
| Aerobic respiration | [(CH2O)n] + O2CO2 + H2O + Energy (ATP) |
| Saprobic microorganisms | decomposers; most have rigid cell wall and cannot engulf large particles of food; to compensate, they reelase enzymes into the EC environment and digest the food particles into smaller molecules that can be transported into the cell. |
| Obligate saprobe | exist strictly on dead organic matter in soil and water and are unable to adapt to the body of a live host |
| Facultative parasite | saprobe that infects a host; which usually occurs when the host is compromised, so microbe is considered an opportunistic pathogen |
| Parasitic microorganisms | live in or on the body of a host, which they harm to some degree (pathogenic); live on body—ectoparasites; in organs or tissues—endoparasites; within cells—intracellular parasites. Pathogens |
| Obligate parasites | unable to grow outside of a living host |
| Obligate intracellular parasite | extreme but relatively common; ex. viruses since they parasitize host genetic and metabolic machinery. |
| Transport mechanisms for nutrient absorption | occurs across cell membrane |
| Osmosis | diffusion of water through a selectively permeable membrane; Water will diffuse from side of higher water concentration to side with lower water concentration. |
| Tonicity | refers to the effect of an extracellular solution on the volume of the cells it surrounds. Used to describe a solution and how that solution affects cell volume. Refers to the effect of an extracellular solution on the volume of the cells it surrounds |
| Isotonic | ECF has same concentration of nonpenetrating solutes as ICF |
| Hypotonic | ECF has lower concentration of nonpenetrating solutes than ICF - the cell would swell with water. |
| Hypertonic | ECF has higher concentration of nonpenetrating solutes than ICF - the cell would shrivel as water left the cell |
| Adaptations to osmotic variations in the environment | microbes will adapt accordingly; in hypotonic environments, will have cell wall that protects from bursting, might have vacuoles act like water pumps. hypertonic environments, cell will restrict loss of water/ increase salinity of internal environment. |
| Driving force of transport | atomic/molecular movement—natural tendency of atoms and molecules to be in constant random movement.Diffusion |
| Simple diffusion | Pertains to small nonpolar molecules like oxygen, lipid soluble molecules |
| Facilitated diffusion | mediated diffusion for polar molecules/ions; uses a carrier protein w/specificity for a certain molecule; Protein will undergo conformation, will transport the molecule, release it into/out of the cell, and then re-conform to original shape. |
| Saturation | rate of transport limited to the number of binding sites on the transport proteins. Once binding sites full, rate of transport has reached a steady state—further addition of the substance may increase, but rate of transport has reached its limit. |
| Active transport | Transport of nutrients against the diffusion gradient, Transport of nutrients in the same direction as the natural gradient but faster than diffusion alone; Presence of specific membrane proteins; Expenditure of energy |
| group translocations | coupled transport of a nutrient with its conversion to a substance that is immediately useful inside the cell |
| Endocytosis | Eating and drinking by cells; cell encloses the substance in its membrane, simultaneously forming a vacuole and engulfing it. |
| Phagocytosis | ingestion of whole cells or large solid matter |
| Pinocytosis | ingestion of liquids (oils, molecules in solution) |
| Temperature adaptations-- three cardinal temperatures | Minimum, optimum, and maximum temperature; temperature adaptation can also be expressed as a description of whether an organism grows optimally in a cold, moderate, or hot temperature range. |
| Psychrophile | microorganism w/ optimum temp below 15C and is capable of growth at 0C; obligate to cold; rarely pathogenic. Hard to work with since room temperature can be lethal. Refrigeration incubates rather than inhibits. |
| Mesophile | organisms that grow at intermediate temperatures between 20C and 40C; inhabit animals, soil, plants, water in temperate, subtropical, and tropical regions. |
| Thermophile | heat loving organisms; grow in soil, water associated with volcanic activity, compost piles, sun exposed habitats. |
| Gas requirements | most influential is O2 and CO2; O2—greatest impact. 3 categories |
| Aerobe | can use gaseous O2 in metabolism and has enzymes needed to detoxify |
| Obligate aerobe | cannot grow without O2 |
| Facultative anaerobe | aerobe that does not require O2 for metabolism and is capable of growth in the absence of it. Organism uses aerobic respiration in presence of O2, but will adopt anerobic method of metabolism (fermentation) in absence of O2. |
| Microaerophile | does not grow at normal atmospheric concentrations of O2, but requires a small amount of it in metabolism. |
| Anaerobe | lacks metabolic enzyme systems for using O2 in respiration |
| Strict or obligate anaerobe | lack enzymes for processing toxic O2, cannot tolerate any free O2 in the environment and will die if exposed to it. |
| Aerotolerant anaerobes | do not use O2 but can survive and grow to a limited extent in its presence. |
| Capnophiles | grow best at higher CO2 tension normally present in atmosphere |
| Acidophiles | live pH extremes—acid pools between 0 and 1 pH |
| Alkalinophiles | live in high levels of basic minerals (up to pH 10). |
| Osmotic pressure | most microbes live in hypo- or hypertonic conditions. Omsophiles live in habitates with high solute concentrations |
| Halophiles | prefers high concentration of salt |
| Facultative halophiles | remarkably resistant to salt, even though they do not normally live in high-salt concentration environments |
| Barophiles | exist in deep sea under pressures up to over 1,000 times normal atmospheric pressure |
| Dehydrated cell stages | spores and cysts; can tolerate extreme drying because of the inactivity of their enzymes. |
| Ecological associations among microorganisms | microbes live in shared habitats, which give rise to complex associations. |
| Symbiosis and symbionts | close nutritional relationships; required by one or both members |
| Mutualism | obligatory, dependent; both members benefit |
| Commensalism and satellitism | commensal benefits, other member not harmed |
| Parasitism | parasite is dependent/benefits; host harmed |
| Synergism | members cooperate and share nutrients |
| Antagonism | some members inhibited/destroyed by others |
| Antibiosis | production of inhibitory compounds such as antibiotics; form of antagonism. |
| Normal microbial flora | microbes that normally live int eh skin, alimentary tract; participate in commensal, parasitic, and synergistic relationships with human hosts |
| The Study of Microbial Growth | Two levels |
| Binary fission | The basis of population growth; Parent cell enlarges, duplicates chromosome, forms central transverse septum that divides the cell into two daughter cells; repeated at intervals |
| The rate of population growth | Generation or doubling time |
| Exponential | Geometric increase |
| The population growth curve | time required for complete fission cycle is called generation/doubling time. Length of generation time is a measure of the growth rate of an organism. Bacteria are notoriously rapid. |
| Lag phase | flat period when population appears to not be growing or is growing at less than the exponential rate |
| Exponential or logarithmic (log) phase | period during which growth curve increases geometrically; phase will continue as long as cells have adequate nutrients/favorable environment |
| Stationary phase | population enters survival mode in which cells stop growing/grow slowly; curve levels off b/c rate of cell inhibition or death balances out the rate of multiplication due to depleted nutrients and oxygen in addition to excretions into growth medium. |
| Death phase | cell death at exponential rate (perishing in own wastes); does not mean all cells are dead—viable cells often remain many weeks/months after death phase begins. |
| Practical importance of the growth curve | important in microbial control, infection, food microbiology, and culture technology |
| Chemostat | automatic growth chamber—continuous culture system that can admit a steady stream of new nutrients and siphon off used media and old cells, stabilizing growth rate and cell number. |
| Turbidity assessment | observation of a tube of clear nutrient solution; cloudy = microbes grow in it. Cloudier = larger population size. |
| Direct or total cell count | counting the number of cells in a sample microscopically using cytometer microscope slide which is then used to estimate the number of cells in the total sample. |
| Coulter counter | electronically scans a culture as it passes through a tiny pipette; each cell is detected by an electronic sensor as it passes by. |
| Psycrophile | microorganism that has optimum temperature below 15C and is capable of growth at 0C; obligate to cold; rarely pathogenic. Hard to work with since room temperature can be lethal. Refridgeration incubates rather than inhibits |
| Chemoautotroph | two types—chemoorganic, which use organic compounds for energy and inorganic compounds as carbon source, and lithoautotrophs, which requires neither sunlight nor organic nutrients, relying totally on inorganic materials. |
| Isotonic | Extracellular environment has same concentration of nonpenetrating solutes as intracellular environment |
| Heterotrophy | organism that must obtain its carbon in an organic form ; since organic carbon originates from bodies of other organisms, heterotrophs are dependent on other life forms. Things that meet carbon requirements |
| Mesophile | organisms that grow at intermediate temperatures between 20C and 40C; inhabit animals, soil, plants, water in temperate, subtropical, and tropical regions. |
| Saprobic microorganisms | decomposers; most have rigid cell wall and cannot engulf large particles of food; to compensate, they release enzymes into the EC environment and digest the food particles into smaller molecules that can be transported into the cell. |
| Obligate saprobe | exist strictly on dead organic matter in soil and water and are unable to adapt to the body of a live host. Facultative parasite |
| Parasitic microorganisms | live in or on the body of a host, which they harm to some degree (pathogenic); live on body—ectoparasites; in organs or tissues—endoparasites; within cells—intracellular parasites. Obligate parasites are unable to grow outside of a living host. |
| Obligate intracellular parasite | extreme but relatively common; ex. viruses since they parasitize host genetic and metabolic machinery |
| Name 2 types of molecular movement that do not require energy | Simple diffusion; osmosis |
| What is the term for a type of molecular movement that is specific, uses a protein carrier, and does not consume energy? | Facilitated diffusion/mediated transport |
| Which type of molecular motion moves substances against a gradient? | Active transport |
| Explain how group translocation works. | Coupled transport of a nutrient with its conversion to a substance that is immediately useful inside the cell |
| What is the term for taking in solid particles using cytoplasmic extensions? | Endocytosis. Phagocytosis is used for solid materials. |
| Why do aerobes and facultative aerobes need enzymes like catalase? | To process toxic oxygen products |
| Would you expect an anaerobe to have catalase? | No, because anaerobes does not tolerate oxygen and will die if exposed to it. if the anaerobe was a facultative anaerobe, it would be more likely to have catalase since it can metabolize by aerobic or anaerobic respiration. |
Created by:
mbtrimm
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