Chapter 7 - Microbial Nutrition, Ecology, and Growth Flashcards
What are nutrients?
Nutrients are acquired from the environment and used for cellular activities
What is a substance called, whether in elemental or molecular form, that must be provided to an organism?
Essential nutrient
_____________ are required in relatively large quantities, and play a principal role in ____ ________ and ____________.
Macronutrients
cell structure
Metabolism
What is another name fro trace elements?
Micronutrients
___________ are present in smaller amounts, involved in _______ function and maintenance of ______ ________.
Micronutrients
enzyme
protein structure
What is an atom or simple molecule that contains a combination of atoms other than carbon and hydrogen called?
Inorganic nutrients
What is the name of a nutrient that contains carbon and hydrogen atoms, that is usually the product of living things?
Organic Nutrients
Examples of Principal Inorganic Reservoir of Elements.
Manganese, molybdenum, cobalt, nickel, zinc, copper, other trace elements— various geologic sediments
What is a Heterotrophs?
An organism that must obtain its carbon in organic form
What is formed by aerobic respiration and dependent on other life forms?
Heterotroph
_________ are carbon sources that exist in a form simple enough for ________, larger molecules must be ________ by the cell before absorption.
Heterotrophs
absorption
digested
What is called a “Self-feeder”, is an organism that uses inorganic CO2 as its carbon source, has the capacity to convert CO2 into carbon compounds, and is not nutritional dependent on other living things?
Autotroph
What is a phototroph?
Microbes that photosynthesize
What are microbes that gain energy from chemical compounds called?
Chemotroph
What captures energy from light rays and transform it into chemical energy that can be used for cell metabolism?
Photoautotrophs
Photoautotrophs produce what that can be used by themselves and heterotrophs?
Organic molecules
What uses organic compounds for energy and inorganic compounds as a carbon source?
Chemoautotrophs
What is lithoautotrophs?
Require neither sunlight nor organic nutrients and rely totally on inorganic materials
How are methanogens formed?
Formed in anaerobic, hydrogen-containing microenvironments of soil, swamps, mud, or intestines of some animals
Chemoautotrophs that produce methane from hydrogen gas and carbon dioxide are called?
Methanogens
Methanogens can be used for ?
Fuel and plays a role as a greenhouse gas
What are a majority of heterotrophic microorganisms called?
Chemoheterotrophs
Chemoheterotrophs get energy how?
By oxidizing chemical compounds
Chemoheterotrophs derive both carbon and energy from what?
Organic compounds
What is complementary to photosynthesis, and Earth’s balance of energy and metabolic gases is dependent on this reaction?
Aerobic Respiration
Aerobic Respiration is what principal pathway in animals, protozoa, fungi, and aerobic bacteria for obtaining?
Principal Energy Yielding Pathway
What is a Decomposers of plant litter, animal matter, and dead microbes, and Important in recycling nutrients held in organic materials?
Saprobic Microorganisms
Most saprobes have what and cannot do what with food?
Rigid cell wall and cannot engulf large particles of food
Saprobic Microorganisms release ______ into the environment to _____ food into smaller particles that can be ____________ into the cell.
enzymes
digest
transported
What must be taken into the cell and what must be taken out?
Necessary nutrients in and waster materials out
What is too nonselective to screen the entrance or exit of molecules?
Cell wall
What is diffusion?
The movement of molecules in a gradient from an area of higher density or concentration to an area of lower density or concentration
Diffusion across a cell membrane is determined by the ___________ _________ and the _________ of the substance.
concentration gradient
permeability
What is Osmosis?
The movement of water across a selectively permeable membrane.
What does it mean when a membrane is selectively or differential permeable?
The membrane has passageways that allow the passage of water but not other dissolved molecules
What are the conditions called when the solute concentration in the external environment is equal to the cell’s internal environment, Diffusion of water proceeds at the same rate in both directions, and are generally the most stable environments for cells, already in an osmotic steady state with the cell?
Isotonic Conditions
Hypotonic conditions cause a cell without walls to _______ and can _____.
Swell
Burst
What kind of condition is present when Solute concentration of the external environment is lower than that of the cell’s internal environment?
Hypotonic Conditions
What is the most hypotonic environment and why?
Pure water is the most hypotonic environment because it has no dissolved solutes
What are Hypertonic Conditions?
Environment outside the cell has a slightly higher concentration of solutes than inside the cell.
What does it mean when the cell has High osmotic pressure?
High osmotic pressure forces water to diffuse out of the cell and Limits the growth of microbes
Hypertonic conditions are the principle behind using what to preserve food?
Concentrated salt and sugar solutions
What is it called when there is little stress on cells?
Isotonic Conditions
Where do bacteria and amoeba live?
Fresh water ponds or Hypotonic environments
How does a amoeba move excess water out of the cell?
Utilize a contractile vacuole that constantly moves excess water out of the cell; requires energy
In hypertonic environments Cells must ______ the loss of water to the environment or increase the _______ of their internal environment.
restrict
salinity
What is Facilitated diffusion?
It is a mediated transport.
What Utilizes a carrier protein that will bind a specific substance and where Binding changes the conformation of the carrier proteins so that the substance is moved across the membrane?
Facilitated diffusion
What does it mean when a carrier proteins exhibit specificity?
They bind and transport only one or a few types of molecules
What is Active Transport?
Transport of nutrients against the diffusion gradient or in the same direction as the natural gradient but at a rate faster than by diffusion alone
What has the Presence of specific membrane proteins (permeases and pumps); and Expenditure of energy?
Active Transport
Specialized pumps carry what kinds of ions across the membrane?
K+, Na+, and H+
What is Group translocation?
Couples the transport of a nutrient with its conversion to a substance that is immediately useful inside the cell
What is Endocytosis?
Transport of large molecules, particles, or liquids across the cell membrane by certain eukaryotes and requires expenditure of energy
What is endocytosis by amoebas and certain white blood cells that ingest whole cells or large solid matter?
Phagocytosis
What is the entry of oils or molecules in solution into the cell?
Pinocytosis
What are some Environmental Factors That Influence Microbes?
Heat Cold Gases Acid Radiation Osmotic pressure Hydrostatic pressure Other microbes
What is cardinal temperature?
Range of temperatures for the growth of a given microbial species
What is the first range of cardinal temperature?
Minimum temperature
What is the second cardinal temperature range?
Maximum temperature
What is the last cardinal temperature range?
Optimum temperature
What is Minimum temperature?
The lowest temperature that permits a microbe’s continued growth and metabolism.
What happens when a microbes temperature is below minimum?
Its activities are limited
What is maximum temperature?
Highest temperature at which growth and metabolism can proceed.
What happens if the microbes temperature rises slightly above maximum?
If the temperature rises slightly above maximum, growth will stop
What happens if the temperature rises pass maximum rate?
If the temperature continues to rise, enzymes and nucleic acids will become denatured, or permanently inactivated
What is optimum temperature?
Intermediate temperature range between minimum and maximum
What does optimum temperature promote in a microbe?
Promotes the fastest rate of growth and metabolism
Small _______ differences in bacterial membranes which affect their ______ allow them to ______ at different temperatures
Chemical
Fluidity
Thrive
What is an organism call that has an optimum temperature of 15C, still capable of growth at 0C, but cannot grow above 20C?
Psychrophils
What are psychotrophs?
Grow slowly in the cold, but have an optimum temperature between 15°C and 30°C
What are a Majority of medically significant organisms called?
Mesophiles
At what temperature do mesophiles reach optimum temp?
20°C to 40°C
At what temperature do most human pathogens grow?
30°C to 40°C
At what temperature can an individual species grow?
10°C to 50°C
___________ microbes survive short exposure to high temperatures; common ____________ of heated or pasteurized foods
Thermoduric
contaminants
At what optimum temperature do Thermophiles grow at?
Grow optimally at temperatures above 45°C
Where do thermophiles live and are directly exposed to?
Live in soil and water associated with volcanic activity, compost piles, habitats directly exposed to the sun
Extreme thermophiles grow at what temperature?
Extreme thermophiles grow between 80°C and 121°C
What is the general range of growth for thermophiles?
General range of growth: 45°C to 80°C
Microbes fall into one of three categories, which are?
Those that use oxygen and can detoxify it
Those that can neither use oxygen nor detoxify it
Those that do not use oxygen but can detoxify it
What has the greatest impact on microbial growth?
Oxygen
Cells use ________ to scavenge and neutralize them, such as ________ and ________.
enzymes
Catalase
Superoxide dismutase
Aerobe uses what in its metabolism?
Gaseous oxygen
Aerobes possesses the _______ needed to process ____ _________ products.
Enzymes
Toxic Oxygen
What is obligate aerobe?
an organism that cannot grow without oxygen
What aerobe does not require oxygen for its metabolism, capable of growth without oxygen, can metabolize by aerobic respiration when oxygen is present, and adopts anaerobic metabolism when oxygen is absent?
Facultative anaerobe
What does not grow at normal atmospheric concentrations of oxygen, does require a small amount of oxygen in its metabolism, and usually live in a habitat that provides a small amount of oxygen but not directly exposed?
Microaerophile
What lacks the metabolic enzyme systems for using oxygen in respiration?
Anaerobe
Strict or obligate anaerobes cannot tolerate ____ _________ and will die in its presence.
free oxygen
What lives in highly reduced habitats such as lakes, oceans, and soil?
Anaerobe
What does not utilize oxygen, can survive and grow to a limited extent in the presence of oxygen, and possess alternative mechanisms for breaking down peroxide’s and superoxide, therefore are not harmed by oxygen?
Aerotolerant Anaerobes
What requires an acidic environment for growth, molds and yeasts tolerate acid and are common spoilage agents of pickled foods?
Obligate acidophiles
What live in hot pools and soils that contain high levels of basic minerals, and are a bacteria that decompose urine to create alkaline conditions?
Alkalinophiles
What are Osmophiles?
Live in habitats with high solute concentration
What do obligate haophiles require?
High concentrations of salt for growth (9 to 25% NaCl)
Obligate halophiles have significant _________ to their cell walls and membranes and will ____ in _______ habitats.
modifications
lyse
hypotonic
What is Resistant to salt, even though they do not normally reside in high-salt environments?
Facultative halophiles
What is a general term used to denote a situation in which two organisms live together in a close partnership called?
Symbiosis
What is mutualism?
exists when organisms live in an obligatory but mutually beneficial relationship
What is a called when a relationship benefits one member and not the other?
Commensalism
What does commensal mean?
Receives benefits
What does coinhabitant mean?
Neither harmed nor benefitted
What is a host role in parasitism?
Provides the parasitic microbe with nutrients and a habitat
What is a parasites role in parasitism?
Multiplication of the parasite usually harms the host to some extent
What are biofilms?
Biofilms are mixed communities of different kinds of bacteria and other microbes
What initially attaches to a surface for biofilms?
Pioneer colonizer
What attaches to a pioneer colonizer after attachment?
Other microbes attach to the pioneer or to the polymeric or protein substance secreted by the pioneer
What is it called when cells are stimulated to release chemicals as the population grows to monitor its size?
Quorum sensing
What is the first step in Binary fission?
Parent cell enlarges
What is the second step in Binary fission?
Chromosomes are duplicated
What is the third step in Binary fission?
Cell envelope pulls together in the center of the cell to form a septum
What is the fourth step in binary fission?
Cell divides into two daughter cells
What is it called for the time required for a complete fission cycle?
Generation or doubling time
With happens with each new fission cycle?
The population doubles
As long as the environment remains favorable, what can remain constant?
Doubling effect
How is the length of the generation time measured?
Measured based on the growth rate of an organism
What is a growth curve?
A predictable pattern of growth in a population
What is a fundamental method of laboratory microbiology, that lows for the total number of cells to be countered over a given time period, and traditionally used to observe the population growth pattern called?
Viable count technique
What is the period during which the growth curve increases geometrically and will continue as long as cells have adequate nutrients and the environment is favorable?
Exponential growth or log phase
What is a flat period on the graph when the population appears not to grow, allowing the cells to have a period of adjustment, enlargement, and synthesis?
Lag phase
What happens to the sample during the lag phase when cells are not yet multiplying at their maximum rate?
Population of cells is so sparse that the sampling misses them
What is the stationary growth phase?
Population enters survival mode
Cells stop growing or grow slowly
What stage is it when Limiting factors intensify and cells begin to die at an exponential rate, also the Curve dips downward?
Death phase
What rapidly accelerates the death phase?
Antimicrobial agents
Microbes in the _________ phase are more vulnerable to these agents than those in the _______ phase and actively growing cells are more vulnerable to conditions that disrupt cell _________ and binary fission.
exponential
stationary
metabolism
During what stages of bacterial shedding is the infection more likely to spread to others?
early and middle stages
