Lab Practical 1 Flashcards
Bacillaceae
bacillus, g-pos
Clostridiaceae
bacillus, g-pos
Enterobacteriaceae
bacillus, g-neg
Spirochataceae
spirochete, g-net
Strepococcaceae
coccus, g-pos
Anthrax
Bacillus anthracis
Lyme
Borrelia burgdorferii
Botulism
Clostridium botulinum
Tetanus
Clostridium tetani
Diptheria
Corneybacterium diptheriae
Dysentery
Shigella dysenteriae
Impetigo, boils, sinusitis
Staphylococcus aureus
Strep throat
Streptococcus pyogenes
Syphilis
Treponema pallidum
Pneumonia, bubonic plague
Yersinia pestis
Bacillus, g-pos (2)
Bacillaceae, Clostridiaceae, Corneybacterium
Bacillus, g-neg
Enterobacteriaceae
Spirochete, g-neg
Spirochaetaceae
Coccus, g-pos
Strepococcaceae, Staphylococcaceae
Bacillus anthracis
Anthrax
Borrelia burgdorferii
Lyme
Clostridium botulininum
Botulism
Clostridium tetani
Tetanus
Corneybacterium diptheriae
Diptheria
Shigella dysenteriae
Dysentery
Staphylococcus aureus
Impetio, boils, sinusitis
Streptococcus pyogenes
Strep throat
Treponema pallidum
Syphilis
Yersinia pestis
Pneumonia, bubonic plague
Bacillus shape
rod
Coccus shape
sphere
Vibrio shape
comma
Spirillum shape
corkscrew
Spirochete shape
helix
Staphylo-
Clusters. Cocci
Strepto-
Chains. Cocci, bacilli
What is the purpose of using aseptic technique?
To minimize the probability of contamination of you by your cultures, your culture by you, and of your cultures by the environment.
What tools do you use the incinerator for?
Inoculating loops/needles, and other devices
How do you disinfect forceps?
Place the tips of the forceps into a bowl of alcohol and use the heat of the incinerator to expedite the evaporation of the alcohol.
What steps are taken to minimize the risk of contaminating agar in a petri dish?
Upside down, lift the base off the lid and avoid unnecessary talking, prevent the falling of dust by holding upside down, only open plate as long as is needed.
What is the purpose of the streak isolation technique?
To promote the growth of distinct, separate colonies of a pure culture.
Why incinerate your loop when streaking for isolation?
This helps eliminate excess cells from the loop.
What information on cell morphology can a simple stain provide? What can it not provide?
Shape and arrangement of bacterial cells.
It does not tell us anything about gram-pos vs neg, nor if endospores or other cell structures are present.
Why air-dry a slide before a simple stain?
Air-drying allows the cells to become partially dehydrated, which protects cellular shape and arrangement.
Why heat-fix cells on to a slide?
Heat fixing further dehydrates the cells, protecting their shape and increasing their affinity to the glass slide so that they don’t wash off during staining procedures. Heat fixing also kills vegetative cells, making pathogens safer to work with.
What are the steps of the Gram stain?
- Crystal violet - primary stain
- Gram’s iodine - mordant (increases retention of the stain)
- 95% ethyl alcohol - decolorizer. (removes purple from gram-negative cells)
- Safranin - counterstain.
Gram-positive bacteria
Thick peptidoglycan-containing cell wall. Retain primary stain.
Gram-negative
LPS-containing outer membrane. Lose primary stain, retain counterstain safranin.
What does the Gram stain tell us?
Differentiates between G-pos and G-neg
Gram stain 1
Crystal violet - primary stain
Gram stain 2
Gram’s iodine - mordant
Gram stain 3
95% ethyl alchohol - decolorizer
Gram stain 4
Safranin - counterstain
What is an endospore?
A highly modified cellular structure that remains dormant until environmental conditions become favorable for vegetative growth.
What is an endospore resistant to?
Heat Drying UV light Freezing Many disinfectants/antiseptics
What is sporulation?
The process of endospore formation. It is a highly modified binary fission.
What is the process of sporulation?
- DNA of the cell is replicated
- Spore septum is produced, dividing the future spore from the rest of the cell
- Cell membrane envelops the spore septum
- Outside layers of the spore are added, producing a tough and environmentally stable structure
- Dead vegetative cell will lyse, releasing the endospore
Endospore stain 1
Malachite green - primary stain. Stains the endospore coat.
Endospore stain 2
Water - decolorizer
Endospore stain 3
Safranin - counterstain. Stains the vegetative cells.
Why is heat used in the endospore stain?
Heat softens the endospore coat, increasing its porosity in order to better take up the primary stain (Malachite green).
What bacterial families are known to produce endospores?
Bacillaceae, Paenibacillaceae
What structure is commonly used by bacteria for motility?
Flagella
Are all bacteria motile?
No
