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Chapter 6 microbiology
Terms in this set (124)
cold loving microbes grow at 0℃
moderate-temperature loving microbes
heat loving microbes
Minimum growth temperature
is the lowest temperature at which the species will grow
optimum growth temperature
temperature at which the species grows best
maximum growth temperature
highest temperature at which growth is possible.
ranges and maximum growth temperatures in psychrophiles in the strictest sense
Grow at 0˚C , optimum growth temp 15℃
pychrophiles growth temperature
can grow at 0℃ but has higher optimum temperature 20-30℃ and cannot grow above about 40℃
Grow fairly well at refrigerated temperatures, encountered mostly in low-temperature food spoilage
an organism that is capable of growth between 0℃ 30℃ organism that grow well at refrigerator temos opt growth of 20-30℃
cold loving microbes -10 to 20℃. organism that grows best at above 15℃ and does not grow above 20℃;cold loving microbe
Optimum growth temperature of 25-40℃, most common type of microbe.
What is the optimum temperature for many pathogenic bacteria
most common microbe, moderate temperture loving microbe 10-50℃
microorganism with growth at high temperatures
heat loving microbe.40-70℃Optimum growth temperature of 50-60℃, temperature of water from hot water tap.
Heat loving microbes.
Cannot grow at temperatures below about 45℃. 40-70℃
thermophilic bacteria forms _______ that are unusually heat resistant and may survive the usual heat treatment given in canned goods.
resisting structure formed inside some bacteria
what organisms are Members of archaea,and have opt. growth temp. of 80℃ or higher
hyperthermophiles, extreme thermophiles
Organism that lives in hot springs , and are associated with volcanic activity with sulfur usually important in their metabolic activity
what is pH
acidity or alkalinity of a solution.
bacteria grows best in a pH range between?
pH 6.5 and 7.5 ranges that are near neutrality
microbes tolerant of acidity
optimum grow pH of molds and yeast
peptones and amino acids in some media act as what?
what is buffer?
a substance that tends to stabilize the pH of a solution
what is plasmolysis?
shrinkage of the cells cytoplasm
osmotic pressure is?
the force with which a solvent moves from a solution of lower solute concentration to a solution of higher concentration
what does the addition of salts or other solutes to a solution and the resulting increase in osmotic pressure do?
can be used to preserve foods.
Describe osmotic pressure and what this mechanism does in preservation in foods?
high salt or sugar concentrations draw water out of any microbial cells that are present and prevents their growth.
microbe that lives in environment of extreme temperature,acidity,alkalinity,salinity,or pressure
adapt well to high salt concentrations that they actually require them for growth; require nearly 30% of salt.
do not require high salt concentrations but are able to grow at salt concentrations up to 2%
organism that needs salt to grow
used to solidify microbial growth of some bacteria
higher concentration that increases the osmotic pressure that_____________________
inhibits the growth of some bacteria
A lower concentration of solutes
Chemical requirements for microbial growth
needed for all organic compounds that make up a living cell
an organism that uses organic molecules as a source of carbon and energy
microbe that use CO2 for engergy
14% of dry weight of a bacterial cell
4% dry weight of bacterial cell
sulfur and phosphorus
Nitrogen is used to
to form amino group of amino acids of proteins.
what is nitrogen fixation?
pulls N2 away from atompshere
Used to synthesize sulfur-containing amino acids and vitamins .
Essential for the synthesis of nucleic acids and the phospholipids of cell membranes
where is phosphorus found?
in energy bonds of ATP
Microbes require very small amounts of mineral elements called trace elements.
What are trace elements?
iron,copper,molybdenum and zinc
sometimes added to laboratory medium, but are naturally present in tap water
are microbes that use molecular oxygen O2 for growth
microbes that use molecular oxygen
an organism that requires molecular oxygen O2 to live.
organisms that does not require molecular oxygen and is killed in the presence of O2
an organism that can grow with or without molecular oxygen O2
does not require oxygen and growth only occurs when there is no oxgen
normal molecular oxygen that has been boosted into a higher energy state and is extremely reactive 1 O 2 ¯
Superoxide radicals; superoxide anions
toxic anion with unpaired electron O2¯˙
Superoxide dismutase (SOD)
An enzyme that destroys superoxide . neutralizes
Peroxide anion O2 2¯
oxygen anion consisting of two atoms of oxygen.
peroxidase. H2O2+ 2H+→2H2O
An enzyme that destroys hydrogen peroxide, does not produce oxygen
enzyme that breaks down hydrogen peroxide. breaks down hydrogen peroxide which converts it into water and oxygen. 2H2O2→2H2O+O2
A toxic form of oxygen formed in cytoplasm by ionizing radiation and aerobic respiration. OH·
essential component of the bodys most important defenses against pathogens,phagocytosis
toxic form of oxygen
cannot use oxygen for growth but tolerate it fairly well.
aerobic ; do require oxygen. Grow only in oxygen concentrations lower than those in air.
Organic growth factors
must be directly obtained form the environment.
ex. of organic growth factors
Microbial community that forms as a slimy layer on surface.
What is slime made out of in a biofilm?
is a matrix made up primarily of polysaccharides, also contain DNA and proteins called the slime
complex polymer containing many times its dry weight in water.
A nutrient material prepared for the growth of microorganisms in a laboratory is called
Microbes that are introduced into a culture medium to initiate growth are called
microbes growing in or on culture media
initially contain no living microorganisms.
solidifying agent; agar is added to the medium
A complex polysaccharide derived from a marine alga
incubate at temperatures approaching 100℃ before liquefies
solid complex media
chemically defined medium
exact chemical composition is known
uses organic carbon as sources for energy
organisms that require many growth factors
made up of nutrients including extracts from yeast, meat, or plants, or digests of proteins from these and other sources
liquid form of complex media
solid complex medium
Composition of nutrient agar
peptone,beef extract,sodium chloride,agar,water.
what media contains ingredients such as sodium thioglycolate, that chemically combine with dissolved oxygen and deplete the oxygen in the culture medium.
special media for the cultivation of anaerobic bacteria
Carbon dioxide incubators, simple candle jars are special culture techniques used to grow what types of bacteria?
what is used to grow aerobic bacteria requiring concentrations of CO2 higher or lower than found in the atmosphere,desired CO2 levels are maintained by electronic controls
Carbon dioxide incubator
Microbes that grow better at high CO2 concentration are called
Some Microorganism are so dangerous that they can be handled only under extraordinary systems of containment called
Biosafety level 4 called the hot zone.
Basic laboratory is classified at what level of biosaftey?
Organisms present a moderate risk of infection, are held at what level of biosaftey?
Highly infectious airborne pathogens such as tuberculosis are held at what level of biosaftey?
Media designed to suppress the growth of unwanted bacteria and encourage the growth of the desired microbe
Media that makes it easier to distinguish colonies of the desired organism from other colonies growing on the same plate
a culture medium used for preliminary isolation that favors the growth of a particular microorganism
Culture media used for the growth of chemoautotrophs and photoautotrophs
Chemically defined media
one in which the exact chemical compostion varies slightly from batch to batch
Culture media used for the growth of obligate anaerobes
Culture media used for suppression of unwanted microbes; encouraging desired microbes
Culture media used for differentiating colonies of desired microbes from other
Culture media similar to selective media but designed to increase numbers of desired microbes to detectable levels
A visible mass of microbial cells arising from one cell or from a group of the same microbes
what method is commonly use to get pure cultures
streak plate method
Is a process in which a pure culture of microbes is place in a suspending liquid and quick frozen at temperatures ranging form -50℃ to -95℃.
Two common methods of preserving microbial cultures for long periods
Deep-freezing and lyophilization
A suspension of microbes is quickly frozen at temps. ranging from -50 ℃ to -72℃ and the water is removed by a high vacuum. the remaining powder can be stored
how does bacteria normally reproduce?
Few bacterial species reproduce by
Reproduction of bacterial species forming a small initial outgrowth that enlarges until its size approaches that of the parent cell then separates. new cells bud from old.
reproduction were there is duplication of two cells
Time required for a cell to divide is called
type of scale is used to graph bacterial growth
bacterial growth curve
shows the growth of cells overtime.
What are the four basic phases of growth
lag,log,stationary,and death phases
The period of little or no cell division and it can last for 1 hr or days is what phase
Cells begin to divide and enter a period of growth or logarithmic increase. this phase is called
Cellular reproduction is most active during this phase and generation time reaches a constant minimum
in this phase there is an equilibrium between cell division and death
Number of deaths eventually exceeds the number of new cells formed and the population then enter what phase
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