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90 Cards in this Set
- Front
- Back
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9 environmental factors effecting microorganisms |
Nutrient/energy source Temperature pH Gas Content Salt Concentration Moisture/Water Other organisms Pressure Radiation |
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Adaptation |
Gradual adjustment of anatomy and physiology |
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Nutrition |
Process by which chemical substances called nutrients are aquired from the environment and used in cellular activities like metabolism and growth. |
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Essential nutrient |
Any substance, whether element or molecule, that must be provided to an organism. |
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Two categories of essential nutrients |
Macro and Micronutrients |
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Macronutrient |
Requires in large quantites, play principle roles in cell metabloism and structure (C,H,O) |
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Micronutrient |
Trace elements, requires in much smaller amounts (Mn,Zn,Ni) |
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Organic Nutrient |
Contain basic framework of carbon and hydrogen |
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Inorganic nutrient |
Composed of element or elements other that Carbon and Hydrogen |
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Growth Factor |
Organic nutrient (amino acid and vitamin) that cannot be synthesised by a cell and must be provided. |
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Heterotroph |
Organism that must obtain its carbon in an organic form. This originates from other organisms and thus they are nutritionally dependant on other life forms. |
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Autotroph |
Organisms that use inorganic carbon as a carbin source. They can convert this carbon into organic compounds and are thus not dependant on other life. |
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Phototroph |
organisms that photosynthesise (use light as their energy source) |
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Chemotroph |
Organisms that gain energy from chemical compounds |
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Lithotroph |
Use reduced inorganic compounds as their electron source. |
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Organotrophs |
Use reduced organic compounds as their electron source. |
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Major essential elements for bacterial growth |
C, N, O, P, H, S, K, Na, Fe, Mg, Ca |
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Trace elements |
Needed in small amounts, Zn, Cu, Mn |
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Caron is obtained from |
sugars, lipids, proteins |
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H and O obtained from |
water, oxygen or atmosphere |
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P, N, S obtained from |
organic and inorganic sources |
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Isotonic Condition |
Environment has equal solute concentration to cell |
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Hypotonic |
Concentration of the solute in external environment is lower than inside the cell. Cell swells |
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Hypertonic |
External environment has a higher solute concentration than cells. Cell shrinks. |
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Temperature at which bacteria will grow determined by |
stability of their membranes and proteins |
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What are the three temperatures that an organism has? |
Minimum, optimum, maximum |
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Optimum temperature |
Promotes the fastest rate of growth and metabolism |
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Psychrophiles |
Organisms cant grow above 20, thrive at 15, can grow below 0 |
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Mesophiles |
Grow from 10-50 degrees |
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Thermophiles |
Grow from 45-80 C |
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Extreme thermophiles |
May grow to 250 C |
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Aerobes use oxygen... |
as an electron acceptor in electron transport pathway |
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Aerobes |
require free oxygen to grow. Have enzymes to remive toxic by products |
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Why do aerobes need O2? |
They create toxic chemicals when using oxygen like hydrogen peroxide, superoxide (O2-) etc. Catalase, peroxidase and superoxide dismutase are used by aerobes to remove the toxins. |
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Anerobes |
Doesnt need oxygen for growth |
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Obligate aerobe |
Cannot survive without oxygen |
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Facultative Anaerobe |
Aerobic, capable of living without oxygen if needed |
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Microaerophile |
Aerobe that requires small amount of oxygen but cant grow in anaerobic conditions. |
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Strict (obligate) anaerobes |
Do not use free oxygen and cannot produce enzymes to dismantle reactive axides. Thus damaged or killed by oxygen. |
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Aerotolerant Anaerobes |
Cannot use oxygen for respiration but not damaged by it. |
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Capnophile |
Grow best in the presence of carbon dioxide. |
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Best pH for most microorganisms |
Neutral pH 7 |
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What do acidity and alkalinity affect? |
activity and integrity of enzymes and structural integrity of a cell. |
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Acidophiles |
Prefer acidic enviornment below pH 7 |
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Alkalinophiles |
Prefer a pH above 7 |
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Neutrophiles |
Gorw best around pH7 |
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Most common method of controlling microbial growth |
Dehydration - bacteria require moisture to grow. |
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Halophiles |
Require high salt concentration |
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Nonhalophiles |
Tolerate moderate salt levels |
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Bacteria and ionic concentrations |
Most cannot survive in high ion concentraions, thus food preservation in sugar and salt. |
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Barophile |
Adapted to life under high pressure |
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What osmotic pressure do organisms prefer? |
Isotonic or slightly hypotonic |
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Osmotolerant organisms |
Can adapt to a wide range of concentrations of solutes. |
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Symbiosis |
Two organisms live together in close nutritional partnership, required by one or both members. |
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Non symbiosis |
Organsims are free living, relationship not needed for survival. |
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Mutualism |
Obligatory, dependant, both members benefit. |
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Commensalism |
The commensal benefits, other member not harmed. |
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Parasitism |
Parasite dependant and benefits, host is harmed. |
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Synergism |
Members cooperate and sahre nutrients. |
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Antagonism |
Some members inhibited or destroyed by others. |
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Antibiosis |
Production of inhibitory compounds such as antibiotics to form antagonism |
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Quorum sensing |
interaction of members of a biofilm that results in a coordinated reaction such as inducer molecules and enzymes. By behaving as a unit, the biofilm remains stable. |
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What does a culture media need? |
Provide all essential nutrients, appropriate pH and ion concentration. |
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Synthetic Medium |
Chemically defined medium, essential nutrients supplied as pure chemicals. Expensive. |
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Complex media |
More used. All ingredients are present but precisely defined. |
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What is used in complex media? |
Malted barley, animal tissue, bakers yeast; acid/enzyme digests of meats, caesin, soybean. |
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What is used for solid and liquid culture? |
Solid - agar agar, petri dish iquid - broth, test tube |
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Types of Culture Media |
1. General purpose media 2. Enriched media 3. Selective media 4. Differential media 5. Complex media 6. Transport media 7. Minimal media 8. Defined media |
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General Purpose Media |
Support growth of many microorgs without any special requirements. |
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Enriched Media |
Supplemented with blood, serum or other nutrients to support microorgs with special requirements. 5% sheep blood |
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Selective Media |
One or more agents that favor the growth of a particular microorg, inhibits others. |
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Differential Media |
Grows several types of microbes and distinguishes between different types. |
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Complex Media |
Media contains some ingredients of unknown chemical composition. |
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Transport Media |
Important for conveying certain clinical specimens. |
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Minimal Media |
Contains minimum nutrients possible for colony growth. |
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Defined Media |
All constituents are of known concentration. |
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Pure culture |
Microbial culture containing only a single species of microorganism. |
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Streaking |
Commonly used method of isolating oure cultures. Loop is sterilized through a flame then streaked fresh through the petri dish. |
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Inoculation |
Implantation of microorgs onto or upon culture media |
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Inoculum |
Material used in an inoculation |
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Culture |
The visible accumulation of microorgs in or on growth medium |
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Colony |
Macroscopic cluster of cells appearing on a solid medium. |
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Isolation |
Separation of microbial cells to create discreet colonies / pure culture. |
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Four phases of microbial growth |
Lag Phase Logarithmic / exponential phase Stationary Phase Death / decline Phase |
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Growth Curve |
A graphic representation of a closed population over time. |
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Lag Phase |
Cells are not multiplying but are metabolically active. |
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Log / exponential Phase |
Viable cells increase in a logarithmic progression and reach the maximum rate of cell division. Continues as long as they have adequate nutrition. |
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Stationary Phase |
Cells enter survival mode where they stop growing or grow slowly. Due to decrease in nutients etc. |
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Death / Decline Phase |
Nutrient depletion, waste buildup, increased cell death. |
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Growth Curve Exceptions |
An open environment has continuous nutrients. |
