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136 Cards in this Set
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- Back
- 3rd side (hint)
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streak plate
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bacteria in mixed culture is diluted to separate organisms and isolate each in pure culture
one of the visible colonies is re-streaked to obtain a pure culture |
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T/F
All of the cells in a colony will not be genetically identical. |
False; they will be
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T/F
Genetically different organisms can share the same colony morphology |
True
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contaminant
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unwanted org. which has been accidentally introduced into the culture
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Why must the inoculation loop be flamed between each quadrant?
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to prevent confluent growth
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Mixed culture
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a culture with more than one kind if org. displaying growth
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pure culture
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culture displaying growth of one single kind of organism
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colony
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population of cells that originates from a single cell growing on a solid medium
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resident or normal microbiota (flora)
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est. on/in body, but don't produce disease under normal conditions; ca survive and multiply on the body
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Although not harmful to the skin, why must normal flora be ridded of in a surgical scrub?
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Because can become pathogenic (disease-causing in humans) if introduced into tissue or the bloodstream
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Transient microbiota (flora)
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present on the body temporarily, but don't become firmly entrenched
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infectious dose
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number of microorgs or viruses sufficient to establish an infection
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oil immersion objective
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must be used to observe microorgs and magnification achieved is 1000X
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What is the first step in staining cells?
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making a smear
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Heat fixation
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process of making a smear which kills the cells, destroying autolytic enzymes, causing the cells to adhere to the slide
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Staining the cells provides ________
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contrast
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What are the basic shapes of bacteria?
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- coccus (round)
- bacillus/rod - spiral |
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Arrangement of cells?
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- pairs (diplo)
- chains (strepto) - clusters (staphylo) - random |
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Cocci in groups of 4...
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tetrads
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How to bacilli divide?
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Across the short axis only
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3 spiral shapes
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vibrios- curved rods
spirilla - helical shape that's rigid Spirochetes - helical, flexible, resemble corkscrew |
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Filamentous growth (of bacteria)
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some actinomycete bacteria (Streptomyces coelicolor) produce filaments of hyphae
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Hyphae forms _______, which later differentiate and fragment to produce ______.
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mycelium
spores |
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simple stain
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aqueous or alcohol solution of a single base dye
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Stains we use...
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Methylene blue
Safranin Crystal violet |
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Bright field microscope
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specific lenses magnify the image of a cells such that details of its structure are apparent
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compoud microscope
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- what we use
- named this b/c contains a series of ocular and the objective lenses |
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total magnification
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product of the magnification of the ocular lens and the magnification of the objective lens
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Magnification is limited by __________
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resolution
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Resolving power (R)
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closest spacing between 2 points at which the points can still be seen as separate entities
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What is the maximum resolution in a compound light microscope?
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0.2 micrometers
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Immersion oil
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reduces amt of light lost and increases resolution
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What is the path of light in a microscope starting with the light source all the way to your eye?
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light souce > condenser > slide > smear > objective lens > ocular lens > your eye
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condenser (of microscope)
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lens that collects and concentrates light onto object on the stage
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parfocal microscope
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as objective lens changes, specimen should remain in focus
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Explain why a mixed broth culture may appear pure on the simple stain but mixed when different colonies were observed on the streak plate?
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b/c a cell may have 2 organisms with the same cellular morphology and different colony morphologies
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peptidoglycan
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consists of repeating disaccharides attached by a polypeptide to form a lattice
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Gram positive cells have many layers of ________ which make the structure ______. They also contain _______ ____ which provide much of the wall's antigenic specificity.
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peptidoglycan
rigid teichoic acid |
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Gram negative
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few layers of peptidoglycan
outer membrane consists of liposaccharides (LPS) lipoproteins, and phospholipids |
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Stains of a gram stain (in order)
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crystal violet
Iodine Ethanol Safranin |
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Gram positive will stain ____
Gram negative will stain _____ |
purple
red/pink |
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What is the purpose of mordant?
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to allow the dye to be absorbed by the cell
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Endospore
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specialized dormant structure that is commonly found in certain Gram positive rods such as those of the genera Chlostridium and Bacillus
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When does an endospore form?
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in a genetically capable cell when essential nutrients are depleted or when what is unavailable
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Vegetative cell
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can grow and divide under optimal conditions
surrounds endospore until it dies |
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Cryptobiotic state
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state of endospores in which no metabolic activities are occurring
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T/F
Endospores are reproductive structures |
False; they are survival structures
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The process of endospore formation is called _______
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Sporulation
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spore septum
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isolates the replicated chromosome and a small amt cytoplasm
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cortex
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layer of peptidoglycan laid between the two plasma membranes
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spore coat
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spore proteins form this around the outside of the structure
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core (of endospore)
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consists of cell wall, cytoplasmic membrane, cytoplasm and nucleoid
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Dipicolinic acid
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found in all endospores and is located in the core
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Germination
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occurs when an endospore returns to vegetative state
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Outgrowth
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visible swelling due to water uptake and synthesis of DNA, RNA, and bacterial proteins
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What bacteria's endospores are used to indicate effectiveness of autoclaves? Why?
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Bacillus stearothermophiles
Because they are extremely heat resistant |
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Why are endospores important to the food industry?
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b/c they survive processes such as heating, freezing, desiccation, treatment by chemicals, and radiation
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Clostridium botulinum
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the causative agent of botulism
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botulism
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spore-forming anaerobic bacillus anaerobic bacillus
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What is the primary stain, mordant, decolorizer and counterstain of endospore staining?
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malachite green
heat water safranin |
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Two genera that commonly form endospores and their gram reaction and morphology
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Clostridium and Bacillus
- Gram pos - rod shaped |
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Process of sporulation
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spore septum forms > forespore > cortex > spore coat is formed around structure
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forespore (of endospore)
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double layered plasma membrane that surrounds genetic material
forms from spore septum |
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3 common diseases associated with Gram positive spore forming rods
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Tetanus
Gangrene Botulism |
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What gives an endospore its heat resistance?
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Calcium complexed with dipicolinic acid
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Mycobacterium
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aerobic, non-endospore forming, nonmotile, rodshaped bacteria that possess mycolic acid
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Mycolic acid
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lipid components complexed to peptidoglycan of mycobacterial cell wall
makes cells difficult to stain by traditional procedures |
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Why are cells of Mycobacterium called acid-fast?
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b/c they resist decolorization
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carbol-fuschin (red stain)
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primary stain of acid fast staining
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Purpose of phenol?
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along with heat, enhances penetration of fuschin into lipid of cell
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Decolorization of acid fast
Counterstain of acid fast |
acid alcohol (3% HCl in ethanol)
methylene blue |
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Mycobacterium cell wall has a _______ nature, which may render the cell strongly impermeable to _______ and may explain the ____ growth in the species.
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hyrophobic
nutrients slow |
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egg albumin
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high protein content
used to make smear for acid fast stain |
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Chemical responsible for acid fast property of Mycobacterium
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Mycolic acid
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What are two disease caused by members of the genus Mycobacterium
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Tuberculosis
Leprae |
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Are acid fast bacteria Gram (+) or Gram (-)? Explain.
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Gram (+) b/c they are harder to penetrate due to thicker peptidoglycan layer
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basal body or motor
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complex of proteins in the cell envelope that anchor bacterial flagella
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hook
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connects the basal body to the extracellular component of the flagellum, the filament
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the filament is made up of __________ proteins
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flagellin
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What provides the energy to rotate the flagellum?
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proton gradient, sometimes a Na+ gradient
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Where does the force to spin the motor proteins come from?
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Protons from the periplasm flowing back into the cell through Mot proteins
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Mot proteins
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protein located adjacent to motor that allows the flow of protons from periplasm back into the cell
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Monotrichious
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single flagellum attached at one end
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Lophotricious
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"tuft" of flagella are attached at one end
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Amphitricious
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one or more flagella attached at each end
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Peritricious
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flagella found at multiple locations of bacterial cell
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Motility test medium
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used to determine whether microorganisms possess flagella and thus are capable of motility
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tetrazolium salt (TTC)
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used as an electron acceptor
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Direct microscopic count
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method for enumerating bacteria in which all the cells are counted for (live and dead)
uses Petroff-Hausser cell counter or hemocytometer |
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Standard plate count
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AKA viable count
method of quantifying organisms counts all living cells |
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spread plate
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aliquots of diluted bacteria are spread onto surface of appropriate medium in Petri dishes using a 'hockey stick'
for aerobic growth |
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pour plate
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aliquots placed in empty P. dish and appropriate melted and tempered medium is added
for anaerobic organisms |
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What is considered a countable plate?
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30-300 colonies
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Turbidity
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how much light travels through
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3 methods for enumerating bacteria and advantage and disadvantage for each
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1. direct microscopic count
2. standard plate count 3. turbidimetric assay 1. rapid, but counts living and dead cells 2. slower cause incubation but counts only living cells 3. rapid but cannot use microorganisms that grow in clumps |
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Potable water
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water thats saw to drink
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enteric disease
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those infecting gastrointestinal tracts
transmitted by fecally-contaminated water |
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Types of enteric diseases
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typhoid fever (Salmonella typhi)
cholera (Vibrio cholerae) dysentery (Shigella dysenteriae) |
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Coliforms are __________________
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aerobic or facultative anaerobic Gram-neg non spore forming rods that produce gas from lactose
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_________ is used as the indicator organism for fecal contamination in U.S.
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E. coli
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total coliform count
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indicates sewage pollution
indexed by method called Most probable number |
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Most probable number (MPN) technique
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coliform count method which relies upon characteristics of gas production from lactose
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Series of tests in MPN
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Presumptive > Confirmed > Completed
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Selective medium
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nutrient medium designed to FAVOR growth of certain microbes and to inhibit undesirable competitors
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Differential medium
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medium providing visible indication of a physiological characteristic of a microorg.
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Eosin methylene blue agar (EMB)
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selective and differential
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Pasteurization
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gentle heating to eliminate organisms that cause spoilage
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Temp above optimum ____________
Temp below optimum ____________ |
denatures enzymes and destroys cellular structures
slows enzyme activity and solidifies lipids |
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UV radiation causes _____ _____ to form within DNA
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thymine dimers
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Lethal mutation
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when mutation causes cell to be unable to make necessary enzymes
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solution
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solute dissolved in solvent
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T/F
Most cells are approx. 75% water |
False. 70%
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Plasmolysis
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pulling away of plasma membrane from cell wall in hypertonic environment
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Halophiles
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orgs. that grow in hypertonic or high salt solutions
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Extreme halophiles
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thrive in solutions of 15-30% NaCl
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Disinfectants
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kill or inhibit growth of pathogenic orgs.
Too harsh to be applied to skin |
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Antiseptic
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don't harm living tissue, can be applied to skin but not necessarily safe for ingestion
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Zone of inhibition
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zone in which no bacterial growth occurs
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Antimicrobial agents
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disinfectants and antiseptics
reduce/eliminate number of microbial cells |
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Cidal agents
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lethal to microorgs.
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Disinfectants
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kill or inhibit growth of pathogenic orgs.
Too harsh to be applied to skin |
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Antiseptic
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don't harm living tissue, can be applied to skin but not necessarily safe for ingestion
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Zone of inhibition
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zone in which no bacterial growth occurs
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Antimicrobial agents
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disinfectants and antiseptics
reduce/eliminate number of microbial cells |
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Cidal agents
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lethal to microorgs.
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Static agent
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inhibits (rather than kills) microorganisms
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Why is Pseudomonas aeruginosa of concern to hospitals?
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because it is resistant to antiseptics and disinfectants
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Minimum inhibitory concentration
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amt of drug at outer edge of zone of inhibition
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mode of action
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the way through which chemotherapeutic drugs kill or inhibit growth of pathogens
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virulence factor
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considered this if capsule enhances organisms ability to cause disease
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Capsules will only be formed by capable bacteria in the presence of _______ _______
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excess nutrients
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Color of capsule stain
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background - dark purple red
cells - reddish brown capsules - remain unstained and look like clear surrounding of cells |
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_______ is the main component of capsules
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Water
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Functions of capsule
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- prevent desiccation of cell
- attachment - resist phagocytosis - reserve energy store (survival structure) |
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A ___________ ___________ is a good method for isolating organisms from a mixed culture.
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a. Streak plate
b. Petri dish c. Lab partner d. Inoculating loop |
Streak plate
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Function of Bacterial vs Eukaryotic Flagella
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Bacterial: rotation
Eukaryotic: flexible whipping action |
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