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Chapter 3 Microbiology
Microbiology: A Systems Approach 4th Edition
Terms in this set (88)
What are the Five I's to culturing microorganisms?
Inoculation, Incubation, Isolation, Inspection, Identification
Introduction of microbes into media for culture. How you start the growth curve. Provides an environment in which they multiply.
Place in an environment to induce growth. Culture is any growth that appears in or on the medium after incubation. Usual temperatures 20-40 degrees celcius. (In lab set to human body temp: 37 degrees celcius). Microbial growth in liquid medium: cloudiness, sediment, scum, color. Microbial growth on solid medium: colonies: visible masses of piled up cells, atleast 1 X 10^8 cells present to see a colony. Log, stationary, and even death phases present
To get a single bacteria in culture (one colony, a discrete sample) of one type of bacteria (axenic). Contaminated- more than one
What does it look like or what biochemical tests can be used to see differences
Use the clues and figure out what is causing the problem and then decide how to treat the problem.
water based solutions that do not solidify at temperatures above freezing and that tend to flow freely when the container is tilted. Ex: broths, milks, infusions. NB-nutrient broth
provides a firm surface upon which cells can form discrete colonies. Used to isolate bacteria and fungi
exhibit a clotlike consistency because they contain an amount of solidifying agent that thickens them but does not produce a firm surface.
liquefiable solid media
sometimes called reversible solid media, contain a solidifying agent that changes their physical properties in response to temperature.
complex polysaccharide isolated from the red alga gelidium. Solid at room temperature, liquefies at 100 degrees celcius and once liquefied, does not begin to solidify until it reaches 42 degrees celcius. Ex: NA, Mueller Hinton, MSA, EBM, McConkeys
Defined (synthetic) media
Media whose chemical compositions are precisely chemically defined. Useful in research. Ex: MSA, mannitol salt media
Contains at least one component that is not chemically definable. Contains extracts of animals, plants, or yeasts. Examples: blood, serum, meat extracts or infusions, milk, yeast extract, soybean digest, peptone, NA, EMB, blood
General purpose media
grows as broad a spectrum of bacteria as possible. Complex media that contains a mixture of ingredients that support a wide variety of microbial life. Ex: Nutrient agar
Contains complex organic substance that fastidious bacteria require for growth. Contain growth factors: specific vitamins or amino acids Ex: blood agar or chocolate agar
contains one of more agents that inhibit the growth of certain microbes. Encourage a select microbe to grow. Generally by including an ingredient that inhibits the growth of other organisms. Important in primary isolation of a certain type of microorganisms from a mixed sample. Ex: feces, saliva, skin, water, and soil
Allow multiple types of microorganisms to grow, but display visible differences between colonies. Differences in colony size or color, media changes or formation of gas bubbles or precipitates. Variations of certain ingredients that cause a color change. Ex: Blood agar
Used as an enrichment medium for fastidious microbes as well as differential media
enzymes that lyse red blood cells to release iron-rich hemoglobin for growth
complete lysis of red blood cells
incomplete lysis of red blood cells
What are the two medias that can be both selective and differential?
MacConkey Agar, EMB and Mannitol salt agar
MacConkey Agar, EMB
selects for enteric bacteria. Differentiate between Lac+ and Lac-
Mannitol Salt Agar
Selects for staphylococcus sp. Differentiates between MF and NMF
used to maintain and preserve specimens that have to be held for a period of time before clinical analysis or to sustain delicate species that die rapidly in not held under stable conditions.
used by technologists to test the effectiveness of antimicrobial drugs and by drug manufacturers to asses the effect of disinfection, antiseptics, cosmetics, and preservatives on the growth of microorganisms.
used by industrial and environmental microbiologists to count the number of organisms in milk, water, food, soil, and other samples
contains a substance that absorbs oxygen or slows the penetration of oxygen in a medium, thus reducing its availability.
Carbohydrate fermentation media
Contains sugars that can be fermented (converted to acid) and a pH indicator to show this reaction.
A discrete mound of cells formed on solid nutrient surface. Consists of just one species and no other if formed from a single cell. Nutrient agar is needed to see a colony
Requirements for isolation
a small number of cells must be inoculated into a relatively large volume or expansive area of media selected to encourage growth, a relatively firm surface, a petri dish, inoculating tools such as an inoculating loop
Streak plate method
A sample is spread across the surface of a medium with an inoculating loop that gradually dilutes the sample and separates the cells in order to encourage the growth of discrete colonies.
A container of medium that contains only a single known species or type of microorganism
free of other living things except for the one being studied
A container that holds two or more identified, easily differentiated species of microorganisms.
A culture that was once pure or mixed that now contains contaminants, or unwanted microbes of uncertain identity
make a second level culture from a well isolated colony
Biochemical test can determine fundamental chemical characteristics such as?
nutrient requirements, products given off during growth (lac +/- or mannitol fermentation +/-), Presence of enzymes (catalyst), mechanisms for deriving energy
Microbial profiles are determined through combining what?
phenotypic testing, genotypic testing, immunologic testing, macroscopic analysis, microscopic analysis
example of what does it look like
presence or absence of antibiotic resistance gene
what can we see on the plate?
What can we see under the scope?
cultures and specimens collected from patients or the environment. Steam sterilizing(autoclaving) or incineration are used to destroy microorganisms
Formation of an image
Occurs when an object is placed at a certain distance from the spherical lens and illuminated with light. Depending on the curvature of the lens, the image is enlarged to a certain degree, called its power of magnification.
the bending or change in the angle of the light ray as it passes through a medium such as a lens
resolution or resolving power
capacity of an optical system to distinguish or separate the adjacent objects or points from one another.
The method of specimen preparation depends on what?
the condition of the specimen (living or preserved), The aims of the observer: observation, identification, movement, and the type of microscopy available
spread a thin film made from a liquid suspension of cells on a slide, allows the slide to air dry, heat fixing
heat the slide gently after it has been air dried.
Important functions of heat fixing are what?
kills the cells and glues the specimen to the slide
provides contrasts, makes inconspicuous features stand out, dyes impart colors to cells by becoming affixed to them through a certain reaction.
positively charged stain is attracted to negatively charged cell walls. Stick tot he cell and give it color
negatively charged dye is repelled by negatively charged bacterial cell walls. produces a dark background around the cells.
recquire a single cell, its an uncomplicated procedure
size, shape and arrangement
Gram positive bacteria stain what color?
Gram negative bacteria stain what color?
Acid fast stain
differentiates acid-fast bacteria from non-acid fast bacteria: detects the causative agents of tuberculosis and leprosy. Ex: mycobacterium sp.
The hardest microbial to kill is ______
The bacteria that can makes spores is ______
Bacillus and clostridium
Used to distinguish endospores from vegetative cells. Detects endospore-forming members of the genera Bacillus and Clostridium.
Protective layer surround the cells of some bacteria and fungi. An example of negative staining with India ink or special positive stains (special stains)
Tiny, slender filaments used by bacteria for locomotion. An example of a positive staining technique
The term culture refers to the ____ growth of microorganisms in _____.
A mixed culture is
One that contains two or more known species
Resolution is _____ with a longer wavelength of light.
A real image is produced by the
A microscope that has a total magnification of 1,500x when using the oil immersion objective has an ocular of what power?
The specimen for an electron microscope is always
Motility is best observed with a
hanging drop preparation
Bacteria tend to stain more readily with cationic (positively charged) dyes because bacterial surfaces
contain large amounts of acidic substances
What type of media is mannitol salt agar?
selective and differential
What type of media is chocolate agar?
enriched and complex
What type of media is MacConkey agar?
selective, differential, and complex
What type of media is nutrient broth?
general-purpose media and complex
What type of media is Sabouraud's agar?
selective and complex
What type of media is triple sugar iron agar?
differential and chemically defined
What type of media is nutrient agar?
differential and complex
What type of media is SIM medium?
differential and compled
A fastidious organism must be grown on what type of medium?
defined medium or enriched medium
T/F: Agar has the disadvantage of being easily decomposed by microorganisms
False, gelatin can be a disadvantage of being easily decomposed by microorganisms
T/F: A subculture is a culture made from an isolated colony
T/F: The factor that most limits the clarity of an image in a microscope is the magnification.
False, the resolution limits the clarity of an image in a microscope.
T/F: Living specimens can be examined either by light microscopy or electron microscopy.
False, living specimens can be examined with phase contrast or differential interference microscopy
T/F: The best stain to use to visualize a microorganism with a large capsule is a simple stain.
False, a negative stain is the best stain to visual a microorganism with a large capsule.
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