Lecture 6 Flashcards
What is an essential nutrient?
- any substance that must be provided to an organism
- Chemicals that are necessary for particular organisms, which they cannot manufacture by themselves
- Carbon, hydrogen, oxygen, phosphate, and sulfur (CHONPS)
What are macronutrients?
required in relatively large quantities and play principal roles in cell structure and metabolism
What are micronutrients?
also known as trace elements
present in much smaller amounts and are involved in enzyme function and maintenance of protein structure
What is an inorganic nutrient?
Not a product of living things
What are organic nutrients?
- contain carbon and hydrogen atoms and are the products of living things
- simple organic molecules such as methane
- large polymers (carbohydrates, lipids, proteins, nucleic acids)
What makes up microbial cytoplasm?
Water – 70% of all components
Proteins
Organic compounds – 97% of dry cell weight
Elements CHONPS – 96% of dry cell weight
How much of components is water?
70%
How much of dry cell weight is organic compounds?
97%
How much of dry cell weight is CHONPS?
96%
How are most chemical elements available to the cell?
Most chemical elements available to the cell as compounds and not as pure elements
What is a heterotroph?
an organism that must obtain its carbon in an organic form
What is an autotroph?
an organism that uses inorganic CO2 as its carbon source
What does an autotroph have the ability to do?
has the capacity to convert CO2 into organic compounds
Are autotrophs nutritionally dependent on other living things?
No
What are phototrophs?
microbes that photosynthesize
What are chemotrophs?
microbes that gain energy from chemical compounds
What ate chemoorganic autotrophs?
use organic compounds for energy and inorganic compounds as a carbon source
What are lithoautotrophs?
rely totally on inorganic minerals and don’t require sunlight or organic nutrients
What are 2 types of chemoautotrophs?
chemoorganic autotrophs and lithoautotrophs
What is a type of chemoheterotrphs?
Saprobes
What are saprobes and parasites?
- free living organisms that feed on organic detritus from dead organisms
- decomposers of plant litter, animal matter, and dead microbes
- recycle organic nutrients
What are parasites?
derive nutrients from the cells or tissues of a living host
What are pathogens?
cause damage to tissues or even death
What are ectoparasites?
live on the body
What are endoparasites?
live in the organs and tissues
What are intracellular parasites?
live within cells such as the leprosy bacillus and the syphilis spirochete
What are obligate parasites?
unable to grow outside of a living host
How can less strict parasites be cultured artificially?
less strict parasites can be cultured artificially if provided with the correct nutrients and environmental conditions
What are the vast majority of microbes that cause human disease?
chemoheterotrophs
What is sodium important for?
important for certain types of cell transport
What is calcium important for?
stabilizer of cell wall and endospores of bacteria
What is magnesium important for?
component of chlorophyll and a stabilizer of membranes and ribosomes
What is iron important for?
important component of the cytochrome proteins of cell respiration
What is zinc important for?
essential regulatory element for eukaryotic genetics
Do all microbes need Copper, cobalt, nickel, molybdenum, manganese, silicon, iodine, and boron ?
some, but not all
Are metals nontoxic or toxic to microbes?
can be toxic
What can the concentration of metal ions influence?
The concentration of metal ions can influence the diseases microbes cause
What is diffusion?
the phenomenon of molecular movement, in which atoms or molecules move in a gradient from an area of higher density or concentration to an area of lower density or concentration
Are all molecules moving al the time?
yes
As temp increases what happens to molecular movement?
increases
Can molecules travel without collisons with other molecules?
No
What happens when molecules collide?
As a result of these collisions, the directions of colliding molecules are altered and unpredictable
What is osmosis?
the diffusion of water through a selectively, or differentially, permeable membrane
Where does water move in osmosis?
from where there is more water to less water
Are most cells surrounded by free water?
Yes
Does the amount of water entering or leaving have an impact of activity and survival?
Yes, major
What are isotonic conditions?
the environment is equal in solute concentration to the cell’s internal environment
Where are parasites most likely to live in host tissues?
parasites living in host tissues are most likely to be living in isotonic habitats
What are hypotonic conditions?
solute concentration of the external environment is lower than that of the cell’s internal environment
What is the most hypotonic environment?
pure water because it has no solute
What is net direction of osmosis in a hypotonic solution?
net direction of osmosis is from the hypotonic solution into the cell
What happens to cells without a cell wall when they are in hypotonic solutions
swell and burst
What conditions are favorable for bacteria cells? Why?
slightly hypotonic because membrane is fully extended and the cytoplasm is full
What are hypertonic conditions?
the environment has a higher solute concentration than the cytoplasm
What is the net direction of osmosis in hypertonic solutions?
high osmotic pressure forces water to diffuse out of the cell
What are hypertonic solutions used for?
hypertonic solutions such as concentrated salt and sugar solutions act as preservatives for food (salted ham is an example)
What is facilitated diffusion?
- Carrier Proteins transport things across cell membrane
- Only transports from regions of higher to lower so no energy required
What is active transport?
the 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
Does active transport require energy?
yes
What are examples of substances that are transported actively?
Examples of substances transported actively are monosaccharides, amino acids, organic acids, phosphates, and metal ions
What is endocytosis?
- the eating and drinking of cells
- Some eukaryotic cells transport large molecules, particles, liquids, or other cells across the cell membrane requiring the expenditure of energy
How does endocytosis work?
cell encloses the substance in its membrane
simultaneously forms a vacuole and engulfs the substance
What performs phagocytosis?
-accomplished by amoebas and white blood cells when they ingest whole cells or large solid matter
What is pinocytosis?
ingestion of liquids such as oils or molecules in solution
Where does group translocation occur?
only in bacterial cells
What is group translocation?
Molecule transported into cell at same time as it is chemically changed into a slightly different molecule
What does the modification of a molecule prevent after its translocated?
The modification prevents it from leaving the cell
What is an example of group translocation?
glucose phosphorylation
What are cardinal temperatures?
the range of temperatures for the growth of a given microbial species
What is the minimum temperature?
the lowest temperature that permits a microbe’s continued growth and metabolism; below this temperature, its activities are limited
What is the maximum temperature?
the highest temperature at which growth and metabolism can proceed before proteins are denatured
What is the optimum temperature?
an intermediate between the minimum and the maximum which promotes the fastest rate of growth and metabolism
What are the temperature ranges for psychrophiles?
optimum temperature below 15°C
capable of growth at 0°C
obligate with respect to cold and cannot grow above 20°C
storage at refrigerator temperature incubates rather than inhibits them
natural habitats of psychrophilic bacteria, fungi, and algae are lakes, rivers, snowfields, polar ice, and the deep ocean
rarely pathogenic
what are the temperature ranges for psychotrophs?
grow slowly in the cold but have an optimum temperature between 15°C and 30°C
Staphylococcus aureus and Listeria monocytogenes are able to grow at refrigerator temperatures and cause food-borne disease
What are the temperature ranges for mesophils?
majority of medically significant microorganisms
grow at intermediate temperatures between 20°C and 40°C
inhabit animals and plants as well as soil and water in temperate, subtropical, and tropical regions
human pathogens have optimal temperatures between 30°C and 40°C
what are the temperature ranges for thermoduric?
can survive short exposure to high temperatures but are normally mesophiles
common contaminants of heated or pasteurized foods
examples are heat resistant cysts such as Giardia and sporeformers such as Bacillus and Clostridium
What are the temperatures for thermophiles?
grows optimally at temperatures greater than 45°C
live in soil and water associated with volcanic activity, compost piles, and in habitats directly exposed to the sun
vary in heat requirements with a range of growth of 45°C to 80°C
most eukaryotic forms cannot survive above 60°C
What are the temperature ranges for extreme thermophiles?
grow between 80°C and 121°C (aka hyperthermophiles)
What are the atmospheric gases that influence microbial growth?
o2 and co2
What are the oxygen requirements for aerobes?
uses oxygen
What are the oxygen requirements for obligate aerobes?
cannot survive w/o oxygen
What are the oxygen requirements for facultative anaerobe ?
can survive with or without oxygen
What are the oxygen requirements for microaerophile?
cannot grow at normal oxygen levels, but does require small amounts of oxygen to survive
What are the oxygen requirements for anerobe?
doesn’t use oxygen for metabolism
What are the oxygen requirements for obligate anaerobe?
cannot survive in the presence of oxygen
What are the oxygen requirements for aerotolerant?
Do not utilize oxygen but can survive and grow to a limited extent in its presence. They are not harmed by oxygen.
What are capnophiles?
organisms that grow best at a higher CO2 tension than is normally present in the atmosphere
What is pH?
Defined as the degree of acidity or alkalinity of a solution
expressed by the pH scale, a series of numbers ranging from 0 to 14
What pH range do most organisms live in?
6-8
What are acidophiles?
organisms that thrive in acidic environments
Where do Euglena mutabilis grow?
0-1
Where do thermoplasma live
1-2
where do picrophilus thrive
7 but can live at 0
can molds and yeast toleratie acid?
yes and they are the primary spoilage agents of pickled food
What are alkalinophiles?
organisms that thrive in alkaline conditions
Where do natromonas live?
live in hot pools and soils at pH 12
What do proteus do?
can create alkaline conditions to neutralize urine and colonize and infect the urinary system
What are osmophiles?
live in habitats with high solute concentration
What are halophiles?
prefer high concentration of salt
What are obligate halophiles?
Halobacterium and Halococcus grow optimally at solutions of 25% NaCl but require at least 9% NaCl
What are facultative halophikes?
: remarkably resistant to salt, even though they do not normally reside in high salt environments
What do some microbial species produce to absorb and dismantle toxic oxygen?
yellow carotenoid pigments
What can ultraviolet and ionizing radiation be used in?
microbial control
What are barophils?
exist under pressures that range from a few times to over 1,000 times the pressure of the atmosphere
What happens if barophils are exposed to normal pressure?
they will rupture?
What is symbiosis?
a general term to denote a situation in which two organisms live together in a close partnership
What is satellitism?
one provides something the other requires for growth, so one must grow nearby to gain what the other produces
What is antagonism?
an association between free-living species that arises when members of a community compete
What is antibiosis?
the production of inhibitory compounds such as antibiotics into the surrounding environment that inhibit or destroy another microbe in the same habitat
What is synergism?
an interrelationship between two organisms that benefits them but is not necessary for survival
What are examples of bacteria working synergistically?
gum disease, dental caries, and some bloodstream infections involve mixed infections of bacteria interacting synergistically
What are biofilms?
mixed communities of bacteria and other microbes that are attached to a surface and each other
What do biofilms form?
form a multilayer conglomerate of cells and intracellular material
How does a biofilm form?
- a “pioneer” colonizer initially attaches to a surface
- other microbes then attach to those bacteria or a polymeric sugar or protein substance secreted by the microbial colonizers
- attached cells are stimulated to release chemicals as the cell population grows
What is quorom sensing?
used by bacteria to interact with members of the same species as well as members of other species that are close by
What is the structure of a biofilm?
large, complex communities form with different physical and biological characteristics
the bottom may have very different pH and oxygen conditions than the surface
partnership among multiple microbial inhabitants
cannot be eradicated by traditional methods
What is binary fission?
one cell becomes two
How does binary fission occur?
- parent cell enlarges
- duplicates its chromosome
- starts to pull its cell envelope together to the center of the cell
- cell wall eventually forms a complete central septum
What is generation time or doubling time?
the time required for a complete fission cycle, from parent cell to two daughter cells
What does generation do in terms of rate of population growth?
- increases the population by a factor of two
- The length of the generation time is a measure of the growth rate of an organism
What is expontential growth?
as long as the environment remains favorable, the doubling effect can continue at a constant rate
What is the average generation time of microbes?
average generation time is 30 – 60 minutes
What is the shortest possible generation time of microbes?
shortest generation times can be 10 – 12 minutes
What is the generation time of Mycobacterium leprae ?
10 to 30 days
What type of bacteria has a generation time in months?
environmental bacteria
What is the equation to calculate the population size?
Nt = (Ni)2n
Nt is the total number of cells in the population, t denotes “at some point in time”
Ni represents the starting number of cells
the exponent n denotes the generation number
2n represents the number of cells in that generation
What is a growth curve?
a predicable pattern of a bacterial population growth in a closed system can be measured by
How can we predict the growth curve?
placing a tiny number of cells into a sterile liquid medium
incubating the culture over a period of several hours
sampling the broth at regular intervals
plating each sample onto solid media
counting the number of colonies present
What is batch culturing?
Batch culturing is in a closed system
nutrients are finite
no mechanism for the removal of waste products
What is the lag phase of the growth curve?
is a “flat” period of growth due to
-newly inoculated cells require a period of adjustment, enlargement, and synthesis
- cells are not yet multiplying at their maximum rate
- population of cells is so sparse or dilute that sampling misses them
What is the exponential (log) phase?
growth increases geometrically
will continue as long as cells have adequate nutrients and the environment is favorable
What is the stationary growth phase?
cell birth and cell death rates are equal
cell division rate is slowing down
caused by depleted nutrients and oxygen plus excretion of organic acids and biochemical pollutants into the growth medium
What is the death phase?
cells begin to die at an exponential rate due to the buildup of wastes
speed with which death occurs depends on the resistance of the species and how toxic the conditions are
slower than the exponential growth phase
What is theViable nonculturable state (VNC)?
many cells in a culture in the death phase stay alive but are dormant
will not grow on culture medium and are missed in colony counts
What are microbes in the expontential growth phase more vulnerable to?
Microbes in the exponential growth phase are more vulnerable to antimicrobial agents and heat
What are microbes that are actively growing more vulnerable to?
Actively growing cells are more vulnerable to conditions that disrupt cell metabolism and binary fission
What is a chemostat?
automatic growth chamber
admits a steady stream of new nutrients
siphons off used media and old bacterial cells
stabilizes growth rate and cell number
used in research and industrial applications
what is turbidity?
a clear nutrient solution becomes turbid or cloudy as microbes grow in it
the greater the turbidity, the larger the population size
How does a coulter count work?
electronically scans a fluid as it passes through a tiny pipette
How does a flow cytometer work?
works similarly to a Coulter counter, but can measure cell size and differentiate between live and dead cells
How does genetic probing work?
uses real-time PCR to quantify bacteria and other organisms present in environmental or tissue samples
