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92 Cards in this Set
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Nutrition |
Process by which chemical substances called nutrients are acquired from environment and used in cellular activities |
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Essential nutrient |
Element/compound that must be provided to an organism macro |
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Macronutrient |
Required in large quantities |
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Micronutrient |
Required in smaller amounts (iron, zinc, etc) |
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Organic nutrients |
Molecules that contain carbon and hydrogen-- product of living things |
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Inorganic nutrients |
Composed of elements other than carbon or hydrogen-- mineral deposits in the soil, water, or atmosphere |
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Heterotroph |
Organism that obtains carbon in organic form-- dependent on other life forms |
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Autotroph |
Used inorganic carbon dioxide as its carbon source-- converts carbon dioxide into organic compounds-- not dependent on other life forms |
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Growth factor |
Organic compound that cannot be synthesized by an organism and must be provided as a nutrient (cells require 20 amino acids but can't make all so some are obtained through food) |
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What are the main determinants of a microbe's nutritional type? |
It's sources of carbon and energy |
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Phototrophs |
Photosynthesize to get energy |
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Chemotrophs |
Gain energy from chemical compounds |
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Photoautotrophs |
Photosynthetic; converts light energy into chemical energy |
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Oxygenic photosynthesis |
Oxygen-producing (plants, algae, cyanobacteria) |
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Anoxygenic photosynthesis |
No oxygen produced |
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Chemoautotrophs |
Bacteria/archaea that survive on inorganic substances such as minerals and gases |
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What drives the synthetic process of the cell? |
Chemoautotrophs remove electrons from inorganic substrates (hydrogen gas, hydrogen sulfide, sulfur, iron) and combine them with other inorganic substances (carbon dioxide, oxygen, hydrogen) which releases simple organic molecules and energy |
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Methanogens |
Archaea found in extreme habitats-- metabolism adapted by producing methane gas |
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Chemoorganotrophs |
Derive both carbon and energy from organic compounds (majority of heterotrophs) |
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Chemoheterotrophs |
Require organic carbon source |
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Saprobes |
Free living microbes that feed on organic matter released by dead organisms |
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Symbionts |
Derive organic nutrients from bodies of living organisms |
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Saprobe characteristics |
Decomposers of plant litter, animal matter and dead microbes-- can't engulf food, releases enzymes to extracellular environment to digest food particles into smaller molecules that can be transported into cell (bacteria, fungi) |
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Facultative parasite |
Doesn't rely on host for completion of life cycle, but CAN be parasitic |
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Parasites |
Invades the body of a host and uses it as a habitat and source of nutrients and harms the host |
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Pathogens |
Parasitic microbes that grow inside sterile tissues and cause damage/death |
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Ectoparasites |
Live on the body |
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Endoparasites |
Live in organs and tissues |
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Obligate parasites |
So dependent on the host that they can't survive/grow on their own |
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Diffusion |
Net movement of molecules down concentration gradient by random thermal motion-- molecules become dispersed from area of high concentration to area of low concentration which makes them evenly dispersed in solution |
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Increase in what makes molecules move faster? |
Kinetic energy |
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Passive transport |
Does not require energy-- diffuses across the membrane |
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Osmosis |
Diffusion of water through selectively permeable membrane |
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Isotonic conditions |
Environment is equal in solute concentration to cell's internal environment-- diffusion of water proceeds at same rate in both directions so there is no net change in cell volume |
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Hypotonic conditions |
Solute concentration of external environment is low than that of the cell's internal environment-- cells without walls can swell and burst when exposed to this condition |
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Hypertonic environment |
Exposed to solution with higher solute concentration than it's cytoplasm-- forces water to diffuse outside of cell |
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Plasmolysis |
Shrinkage of protoplast in cells without a cell wall |
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Turbid |
Swollen/congested cytoplasmic membrane |
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Amoeba |
Has no cell wall so it must expend extra energy to deal with influx of water-- accomplished with a water vacuole that pushes excess water out of cell |
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Facilitated diffusion |
Transport mechanism that uses carrier protein in membrane that will bind to a specific substance-- changes conformation of carrier protein in a way that facilitates movement of substance across membrane |
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When is facilitated diffusion used? |
When the substance is less permeable and diffusion is unable to transport it |
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Specificy |
Carrier proteins that bind and transport only a single type of molecule |
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Aquaporins |
Water channels; facilitate transport of water molecules following existing osmotic gradient-- regulate volume and osmotic pressure |
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What must a microbe do to ensure constant supply of nutrients? |
Capture nutrients in low concentrations and actively transport them into the cell |
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Carrier-mediated active transport |
Functions with specific membrane proteins that bind ATP and molecules to be transported-- release of ATP drives molecule through protein carrier |
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Group translocation |
Couples transport of a nutrient with its conversion to a substance that's immediately useful inside the cell |
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Endocytosis |
Cell encloses substance in membrane, forming a vacuole and engulfing it |
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Phagocytosis |
Amoebas and certain white blood cells ingest whole cells or large solid matter |
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Pinocytosis |
How liquids enter the cell (oils: molecules in solution) |
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Minimum temperature |
Lowest temp that permits a microbe's growth and metabolism |
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Maximum temperature |
Highest temp that permits growth and metabolism-- any higher can cause denaturation and death |
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Optimum temperature |
Between minimum and maximum temps that promotes fastest rate of growth and metabolism |
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Psychrophile |
Microorganism with optimum temp below 15 degrees C but can grow at 0-- can't grow above 20 degrees C |
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Mesophiles |
Organisms that grow at intermediate temps-- optimum growth temp is 20-40 degrees C-- inhabit animals, plants, soil and water (guardia, bacillus,clostridium) |
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Thermophile |
Microbe that grows optimally at temps greater than 45 degrees C-- live in soil and water |
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Hyperthermophiles |
Grow between 80-121 degrees C |
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Atmospheric gases that most influence microbial growth |
Oxygen and carbon dioxide |
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Singlet oxygen (1O2) |
Produced by phagocytes to kill invading bacteria-- buildup of singlet oxygen can damage and destroy cell |
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Capnophiles |
Grow best at higher carbon dioxide tensions than are normally present in the atmosphere |
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Neutrophiles |
Microorganisms living in soil, fresh water or bodies of plants/animals that live within the range of pH 5.5-8 |
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Acidophiles |
Include Eugenia mutabilis and Thermoplasma-- grows in acid pools between 0-1 pH |
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Alkalinophiles |
Live in pools/soils that contain high levels of basic minerals |
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Syntrophy/cross feeding |
Community feeding of organisms sharing a habitat-- products given off by one organism are usable to another |
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Amensalism |
One microbe causes adverse effect in another-- involves competition and occurs where microbes share space/nutrients |
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Antibiosis |
Release of natural chemicals/antibiotics to kill other microbes (fungi and bacteria use this) |
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Biofilms |
Used as adaptive strategy-- favors persistence in habitats and offers greater access to life sustaining conditions |
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Quorum sensing |
Swimming microbes (planktonic) attracted to surface and settle down-- stimulates cells to secrete slimy/adhesive matrix that binds them to substrate, and once attached cells release inducer molecules |
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Inducer molecules |
Accumulate as cell population grows (can monitor size of their own population)-- stimulates expression of particular gene and synthesis of protein product |
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Binary fission |
How bacteria cells replicate-- parent cell splits into 2 daughter cells |
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Generation time |
Time required for complete fission cycle-- average time for bacteria is 30-60 minutes |
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Chemostat |
Continuous culture system-- admits steady stream of new nutrients off used media and old bacterial cells to stabilize growth rate and prevent culture from entering death phase |
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Cell content |
70% water Proteins 96% CHNOPS |
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Halophiles |
Require high concentration of salt |
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Osmotolerant |
Do not require salt but can tolerate it |
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Lag phase |
Flat period of adjustment, little growth |
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Exponential phase |
Maximum growth |
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Stationary phase |
Nutrients depleted and oxygen gone-- rate of cell growth equal to rate of cell death |
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Death phase |
Cells die as factors intensify |
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Aerobe |
Uses oxygen and can detoxify it |
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Obligate aerobe |
Cannot grow without oxygen |
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Facultative aerobe |
Utilizes oxygen, but can grow without it |
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Microaerophilic |
Require small amount of oxygen |
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Anaerobic |
Does not utilize oxygen |
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Obligate anaerobe |
Lacks enzymes to detoxify oxygen so it can't survive in oxygen environment |
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Aerotolerant anaerobes |
Does not utilize oxygen but can grow in its presence |
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Symbiotic |
Organisms live in close nutritional relationships--required by one or both members |
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Nonsymbiotic |
Relationships not required for survival |
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Mutualism |
Both members benefit |
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Commensalism |
Other member doesn't benefit but not harmed |
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Parasitism |
Parasite dependent and benefits-- host harmed |
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Synergism |
Members cooperate and share nutrients |
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Antagonism |
Some members inhibited/destroyed by others |