Exam 1 Super review Flashcards
- Talk about why microbes are essential
They're everywher producers decomposers drugs/chemicals recyclers damage understand higher forms of life
i. Provides contrast between the specimen and its background
ii. Depends on lens quality
iii. Improved with certain magnification and staining
Definition
i. The capacity to distinguish or separate two adjacent objects
ii. Depends on the wavelength of light that forms image
1. shorter wavelength, or use of electrons, increases the resolution
iii. Also improved with oil immersion (immersion has the same refractive index as glass)
Resolution
Heat-dried
Capsule stain
Air dried
Negative Stain
Bacteria spread out in ink
Negative and Capsule
Heat Fixed
Positive Stain
bacteria spread out in water, then air dried
Positive Stain
kills the bacteria; makes the bacteria adhere; helps the bacteria absorb stain
Heat Fix
one dye is used; reveals shape, size and arrangement (Methylene Blue in class)
Simple Stain
uses a primary stain and a counterstain to distinguish cell types or parts
Differential Stain
Gram stain
acid fast stain
endospore stain
capsule stain
are examples of ____ stain
Differential Stain
surfaces of microbes are negatively charged and attract basic dyes
Positive staining
these dyes are cationic, with positively charged chromophores
Basic dyes
Reduces the refractive loss of light
Oil Immersion
i. Aseptic Technique to prevent contamination.
ii. To transfer bacteria from broth culture to an agar surface - whenever you’re transferring a liquid
Inoculating Loop
i. Used whenever you are transferring bacteria from solid media.
Inoculating Needle
to dilute bacteria so you can isolate into pure culture where each colony comes from one bacteria that is isolated.
Quadrant Streak Plate
tube where liquid agar was cooled while tube was lying down on angle tocreate a sloped agar surface, so there’s more surface area where bacteria can grow.
Nutrient Agar Slant
provides the surface where your smear will be located.
Glass Slide
for smears prepared with positive stains, used to make a target circle on the bottom of the glass slide.
Wax Pencil
stains the background
negative
stains bacteria itself
positive stain
only one dye used
simple stain
more than one dye used
differential
i. improve definition
ii. negative stains background
iii. positive stains bacteria itself
staining
- nigrosine toward one end; transfer small amount to ink and mix; smear with second slide
air dry for (-) stain
heat dry gently if capsule
little shrinkage and bacterial shape/size can be more reliably interpreted.
benefits of air-dry
Looks for glycocalyx in forms of capsule - a protective covering sometimes used for attachment and nutrient reserve
Capsule Stain
- Place heat dried smear in staining rack resting over sink
- Flood smear with enough crystal violet to cover for 1 minute
- Rinse with distilled water
- Blot slide within pages of your bibulous paper tablet
- Oil immersion.
Capsule Stain
The smear with nigrosine air dried is it
Negative stain
i. One stain used-Typically a single positively charged stain+smear is good (methylene blue is good)
ii. give information about shape/arrangement of bacteria
iii. heat fix smear
iv. chromophores
Simple stain
- Place heat fixed smear on staining rack over your sink.
- Flood with methylene blue for 1 minute
- Rinse slide with distilled water
- Blot with bibulous paper
- View with oil immersion.
Simple stain
- makes bacteria stick to slide, kills bacteria, allows bacteria to absorb stain more easily.
Pros for heat smear
The most important stain
Gram
- Gram negative have thin peptidoglycan surrounded by outer membrane with phospholipids and lipopolysaccharide RED/PINK
- Gram positive has thick layer of peptidoglycan and no outer membrane. PURPLE
Gram Stain
- Apply crystal violet for 1 minute
a. primary stain = crystal violet - Wash off stain with distilled water
- Apply Gram’s iodine for 1 minute
a. iodine = mordant = combiens with primary stain to form insoluble crystalline compound. crystals get trapped in thick peptidoglycan but fail to be so where it is thin. - Wash off iodine with distilled water
- Apply 95% alcohol, drop by drop until alcohol runs clear (no more than 3-4)
a. crystal violet is washed out of cells with thin peptidoglycan; destroys outer membrane of gram negatives. - Wash off the alcohol with distilled water
- Apply safranin for 20 seconds.
a. safranin is the counterstain. - Wash off the stain with distilled water.
- Blot dry with bibulous paper
Gram Stain
i. Negative stain + gentle heat fix + adding crystal violet –> differential stain
ii. uses ink to smear/colorb ackground + stain to color the background itself.
iii. Differentiates the capsule from rest of cell
Capsule stain = negative + simple positive stain
Coat is made of keratin and spore specific proteins makes acid/radiation/chemical/disinfectants/dyes/antibiotics difficult to penetrate
Endospores
Interior has high concentrations of calcium and dipicolinic acid which makes _ heat resistant by displacing water and making dehydrated _ non metabolic
Endospores
- Take one of heat fixed smears and place it on screen over steaming water
- Put small piece of paper towel on top of the smear and add enough malachite green to saturate the paper.
a. malachite green primary stain - Steam for 5 minutes while keeping the paper moist with additional stain as needed.
a. since spores resistant to staining. - To avoid stain get on bottom of slide, hold slide with clothespin over steam rather than let the slide sit there.
- remove slide from screen and let it cool; rinse with distilled water for 30 seconds.
- Place the slide on staining rack and counterstain with sfranin for 20 seconds
a. This is the counterstain that stains the vegetative cells. - Rinse the slide and blot dry.
a. Endospores should be green; vegetative cells should be red/pink.
Endospore Stain
i. Contain negatively charged chromophores; typically stain proteins
ii. waxy mycolic acid of wall of bacteria make it difficult to stain with usual dyes, but steaming acilitates the stain entertaining the cell wall.
iii. Typically include cells of genus Mycobacterium
iv. “Acid fast” means that once the stain has entered, subsequent washing with acid-alcohol won’t remove the stain.
Acid Fast Stain
- Add mycobacterium mix it with water. Also add staphylococcus
- Air dry and heat fix smears.
- Place heat fixed smear on screen over steaming water.
- Apply carbolfuchin to cover smear; steam for 5 minutes.
a. primary stain - used to color acid-fast cells; when absorbed, will give pink/red color to acid fast cell wall. - Remove slide from screen and let it cool; rinse with water for about 30 seconds.
- Rinse drop by drop with acid alcohol until run off clear
- Briefly rinse with water
- Place slide on staining rack and counterstain with methylene blue for 30 seconds.
a. counterstains colors any non acid fast cells - Dry with bibulous paper.
Acid Fast Stain
Branched apart 3.5 bya
prokaryotes
Branched apart ~1.5 bya
eukarya from archaea
- Schwann: all animal tissues composed of cells
- Schleiden: All plant tissues composed of cells
- Virchow: All cells only arise from pre-existing cells
Cell theory
- Pasteur and Koch were leading contributors
- The belief that many diseases are caused by the growth of microbes int he body, not by sins, bad character, or poverty.
germ theory of disease
- THe microrganism or other pathogen must be present in ALL cases of the disease
- Thep athogen can be isolated from the diseased host and grown in pure culture.
- The pathogen from the pure culture must cause the disease when inovulcated into a healthy, susceptible lab animal.
- The pathogen must be reisolated from the new host and shown to be the same as the originally inoculated pathogen.
Koch’s Postulates
The four criteria established by Koch to identify the causative agent of a particular disease
i. discovered first antibiotic, penicillin
ii. isolated in 1939 by Ernest Chain and Howard Florey
iii. Extracted from Penicillum mold
Alexander Fleming 1929
i. Dutch linen merchant
ii. First to observe living microbes
iii. Single=lens magnified up to 300X
iv. Very protective of his work
v. father of microscopes
vi. saw animalcules (algae and protozoa)
Anton van Leeuwenhoek 1632-1723
i. Allowed heated air to enter abroth filled flask through a coiled tube
ii. Broth stayed clear, he concluded that microbes can not spontaneously generate from broth.
iii. Opponents claimed he killed the “vegetative force” in the air by heating it.
iv. Air inlet - flame heated air - previously sterilized infusions remain sterile.
Schultze & Schwann, 1839
i. Refuted spontaneous generation of macroscopic organisms
ii. demonstrated maggots don’t generate from meat.
iii. Meat with gauze had no maggots; meat open had maggots hatching into flies.
Francesco Redi Italian mid 1600’s
i. supported spontaneous generation
ii. assumed boiling kills everything
iii. when boiled mutton brother produced large quantities of bacteria he concluded that they spontaneously generated from the broth
iv. also left the lid open for awhile.
f. John Needham 1748 England
i. Boiled the broth longer, sealed the flask, nobacteria grew.
ii. argued that he destroyed the “vegetative force” of the broth and degraded the small amount of air that was there.
iii. Gravy boiled + lid –> w/o lid? bacteria growth. w/lid? no growth.
g. Lazzaro Spallanzani 1765 Italian
i. Used swan-necked flask to demonstrate the dust is associated with microbes in the air
ii. 1861 paper tried to persuade readers that mcirobes do not spontaneously generate
iii. still had some results that were contrary to the idea.
iv. Developed pasteurization
v. Demonstrated what is now known as the Germ Theory of Disease
h. Louis Pasteur, 1859 Frenchman
i. demonstrated thatif dust removed from the air, bacteria don’t grow
ii. demonstrated the presence of heat resistant forms of some microbes
iii. Developed Tyndallization, intermitten boiling that eliminates what we now know to be the endospores that caused Pasteur to have inconsistent results
iv. Explaiining Pasteur’s results (which were sprouting endospores) end belief in spontaneous generation.
i. John Tyndall England 1859
i. Contributed the most to the development of pure culture techniques
ii. Was the first to offer convincing proof that microbes were associated with disease
iii. Developed Koch’s Postulates, a method foas associating a particular organism with a particular disease. (ahtrax, cholera, tb)
iv. Developed pure culture methods
j. Robert Koch, Germany 1870’s
i. Connected infection with microbes - Savior of the Mothers
ii. Failed to convince doctors to wash their hands.
iii. Pioneer of Antiseptic procedures
k. Philipp Semmelweis (1840’s)
i. Pioneer of Antiseptic Surgery
ii. washed hands and heated equipment with phenol and found that it greatly reduced infection
l. Jospeph Lister
i. Discovered endospores
ii. Resulted in final overthrow of Spontaneous Generation
m. Ferdinand Cohn, 1876
i. early belief that some forms of life could arise from vita forces present in nonliving or decomposing matter (flies from manure)
a. Spontaneous Generation
i. the idea that living things can only arise from other living things
Biogenesis
spherical
Coccus
one
singular
spheres in pairs
diplococci
groups of 4 spheres
tetrads
irregular clusters
staph
chains
strpt
packets
cubical packets
rods
bacillus
rods in pairs
diplobacilli
chains
strept
rods laying side by side
palisade
curved rod
vibrio
flagella on outside
spirillum
flagella on inside
spirochete
which bacteria shapes are always solitary
vibrio, spirillum, spirochete
Sizes of bacteria
1 um to 200 nm -ish
single flagellum at one end
small bunches emerging from the same site
flagella at both ends of the cell
flagella dispersed all over the cell
monotrichous lophotrichous amphitrichous peritrichous Flagellar Arrangements
3 parts
filament
hook
basal body
flagella components
Flagella powered by ion channels
Bacteria
Flagella has flagellin, powered by ATP
Archaea
Undulipodia are similar to cilia and flagella
Powered by ATP
Eukarya
Appendange
Rigid tubular strucutre made of pilin protein
iii. Function
1. Join _ cells for DNA transfer called conjugation]
B, G-
i. FIne, hairlike bristles emerging from cell surface of _ domain
ii. Function in adhesion to other cells/surfaces
iii. contribute to virulence
Bacteria G+ G-
i. optional coating of molecules external to the cell wall, made of sugars and/or proteins
ii. two types of layers
Glycocalyx
- Slime Layer
a. loosely organized and attached, thinner - Capsule
a. highly organized matrix of proteins and sugars,
b. tightly attached
c. harder to stain
d. makes bacteria appear shiny
Glycocalyx Layer Types
- protect cells from dehydration
- nutrient source
- allows for attachment to surfaces (biofilms)
- inhibits killing by white blood cells by phagocytosis, contributing to pathogenicity
- considered a virulence factor (plays a role in causing diseases)
Glycocalyx
- Free swimming cells settle on the surface and remain there
- Cells synthesize sticky matrix that holds them tightly to the substrate
- When biofilm grows to certain density (quorum), the cells release inducer molecules that can coordinate a response.
- Enlargement of one cell to show genetic induction, inducer molecule stimulates expression of a particular gene and synthesis of a protein product such as digestive enzymes or toxins.
- Cells secrete their enzymes in unison to digest food particles; survive
Biofilm synthesis
- composed of protein and RNA
- have large and small subunit scattered throughout the cell when non engaged in protein synthesis
a. small unit
i. translates mRNA
ii. contains the RNA that Carol Woese used to distinguish the domains
b. Large unit
i. highly conserved ribozyme (RNA enzyme) used to generate peptibe bonds)
ii. peptidyl transferase
Ribosomes
Sedimentation Rate
70s
80s
Prokaryotic ribosome
Eukaryotic
- pairs of linear chromosomes
- histones
- nucleus
Eukarya
- nucleoid
- ~4k genes
- Bacteria - no histones
- Archaea - histone-like
Prokarya
i. are extra-chromosomal DNA; 1-20 exist per cell
ii. They are transferrable
iii. only in Bacteria and Archaea
iv. None of the genes are required are essential to survival; but are bonuses.
`Plasmid
- alternating NAM and NAD sugars with cross peptide bonds
- separated from cell membrane by periplasmic space that contains digestive enzymes
- Only in bacteria
peptidoglycan
- thick peptidoglycan retains stains such as crystal violet
- 50% of wall has teichoic acids that provides integrity to cell wall; act as pores to admit ions to cell interior
- one periplasmic space
G+ cell walls
a. detected; contains lipid A endotoxin
b. has porins controls entrance of nutrients and antibiotics (which are too big to pass through pores)
G- outer membrane
- has outer membrane of lipopolysaccharide/phospholipid bilayer found outside peptidoglycan portion
- Two periplasmic spaces
- thin peptidoglycan layer
G- cell wall
- have protein, glycoprotein, and polysaccharide
- NO peptidoglycan
- S layer - outer protein lattice that gives strength to the cell wall in extreme environments
Archaea
Which cell wall has outer membrane?
G-
How many periplasmic spaces?
G+ 1
G- 2
Which cell wall type porins?
G-
Which cell type has lipopolysaccharides?
G-
- NO PEPTIDOGLYCAN
- Cell wall has protein, glycoprotein, and polysaccharide
- S layer - an outer protein lattice that gives strength to the cell wall in extreme environments
Archaea Cell wall
i. No sterols in membrane
ii. Phospholipid bilayer with embedded proteins
1. phospholipids contain unbranched lipids/fatty acids.
iii. Functions
1. Providing site for energy reactions
2. Nutrient processing
3. syntehsis
4. Passage of nutrients into cell, discharge of wasts
5. Selectively permeable
Bacteria Cell Membrane
i. Phospholipids contain backwards glycerol, and no fatty acids - isoprene chain - helps them to resist heat.
Archaea Cell Membrane
i. Bacteria - Streptomyces and Bacillus
ii. Molds - Penicillium and Cephalosporium
Source of Antibiotics
a. Natural
b. Selective - should only attack something on microbial cells that wouldn’t be present on the host tissues (peptidoglycan, porin molecules, etc.)
c. Produced by aerobic bacteria and molds
i. Bacteria - Streptomyces and Bacillus
ii. Molds - Penicillium and Cephalosporium
d. low concentrations - communication molecules
i. like inducers
e. high concentrations - kills/inhibits microbes
i. To lower competition for nutrients and space
f. Target bacteria
Characteristics of Antibiotics
drugs attack something om microbial cells thatwouldn’t be present on host tissues
Selective
attacks both microbe and host
Non-Selective
effective on a small range of microbes
i. Target specific cell component that is found only in certain microbes
Narrow Spectrum
i. Target cell components common to most pathogens (ribosomes)
d. Broad spectrum - greatest range of activity
i. beta lactam ring (pretty much for all the cilins)
ii. disadvantage - allergies
iii. Narrow - G+ and syphilis
Narrow G+
Cell wall
Penicillin
i. narrow for G+
ii. downside: allergies
Cell wall
methicilin
i. bad internally (neosporin)
ii. only used topically
cell wall
narrow G+
Bacitracin
i. high toxicity index
ii. need pick line to adimnistrate
iii. only used topically
narrow G+
cell wall
Vancomycin
i. found in tears, saliva, intestinal secretion
ii. Digests peptidoglycan in G+ cell wall
Lysozyme
i. Broad to G+/G-
ii. Downside allergies; resistance; harder to absorb
Broad
cell wall
Ampicillin
Augmentin=amoxicillin+beta-lactamase inactivator
Broad
cell wall
yeah
i. Poor absorption in GI
1. Needs to be injected
Broad
cell wall
Cephalosporins
i. Disadvantages: not selective
ii. only used topically
iii. neosporin
Narrow G-
cell membrane
Polymyxin
i. Athlete’s foot
ii. Disad: bad internally
Narrow fungus
cell membrane
Amphotericin B
i. Disadvantage - targets 80s?
ii. Kids have permanent discolor teeth, slow growth, liver damage
Broad
Both ribosomes
Tetracycline
i. deafness; kidney damage
Broad
Aminoglycoside
70s ribosome
Streptomycin
Aplastic anemia - loss of red bonoe marrow w/LT use
Broad
Aminoglycosides
70s riboosomes
Chloramphenicol
GI upset
Narrow G+
Aminoglycosides
Erythromycin
(Toxicity to the host)/(Toxicity to the microbe)
=Toxicity index (want low)
(Max dose tolerated by host)/(Dose needed to kill the microbe)
= Therapeutic Index (want high)
inert, resting cells produced by G+ Clostridium, Bacillus (the two that cause disease)
Endospores
i. Vegetative cell: metabolically active and growing
ii. Endospore - When exposed to adverse environmental conditions
iii. Capable of high resistance and very long term survival
iv. Hardiest of all life forms
Endospores
iv. tough endospore coat of keratin makes it resistant to chemicals and radiation
Endospore
v. dipicolinic acid and calcium ions displace water; make spore extremely heat resistant
Endospores
i. Survive
ii. Withstands extremes in heat, drying, freezing, radiation, chemical
iii. NOT a means of reproduction
Endospores
d. Germination - return to vegetative growth
Endospores
i. NO CELL WALL
Tenericutes
Think Firm Peptidoglycan
Firmicutes
Think Graceful Peptidoglycan layer
Gracillicutes
- No peptidoglycan in cell wall
- Have S layer
- Histone-like molecules
- unique DNA polymerase
- Ribosomes similar to eukarya
- Unique membrane lipids
Archaea
- Plants
- Animals
- Fungi
- Protisa
Kingdom of Eukarya domain
i. Nutrition and physical environment
1. body temperature?
ii. Growth Characteristics
1. Color, Texture
iii. Metabolism
1. H2S - anaerobe
2. aerobic?
iv. Staining
1. G staining
2. capsule
3. endospore
v. Cell Morphology
1. Cell shape
2. arrangement
3. flagella?
Diagnostic techniques to classify bacteria
i. Genome Analysis
ii. Serology
iii. Phage Typing (virus)
Molecular techniques to classify bacteria
i. shape,
ii. appearance,
iii. flagella
Microscopic morphology
i. colony appearance,
ii. color,
iii. texture
Macoscopic morphology
i. metabolism
ii. temperature
iii. nutrient requirements
Bacterial physiology
Antibodies
Serological Analysis
i. Ribosomal RNA analysis
ii. protein analysis
g. Genetics and molecular analysis
i. The Spirochetes
ii. The Rickettsia Genus
iii. Chlamydiaceae Family
Gracillicutes
G-
- G- human pathogens
- Endoflagellum
- Flexible
- Hides since flagellin inside
Spirochete
Gracilicutes
Lyme Disease
- Barrelia Burgdorferi
a. Vectors - something living that can transmit the microbe
i. tick
b. Reservoirs - source of microbe in nature
i. mouse, deer
c. Transmission
i. Inoculation - not communicable unless preggers
d. Symptoms
i. Primary
1. Bull’s eye
2. rash + flu
ii. Systemic
1. circulation
iii. Secondary
1. all tissues
2. CNS
3. Heart
iv. Tertiary
1. Arthritis
Grancilicutes
Spirochete
Barrelia Burgdorferi
Lyme Disease
a. Vectors
i. human
b. Reservoirs
i. human
c. Transmissions
i. direct contact (mucous membranes/placenta) by human vectors (carriers); sexually transmitted
d. Symptoms
i. Primary
1. chancre/ulcer
2. Highly contagious
ii. Secondary
1. circulation/flu/rash palms and soles
iii. Latency
1. 8+ years
iv. Tertiary damage
1. Gummas 20 years
2. 80% death
3. 20% neurological
e. Polymorphism
i. hides from immune system by antigenic variation; covers self with host molecules
Gracilicutes
Spirochete
Treponema Pallidum - Syphilis
- Small intracellular parasites
- G- cell wall
- Nonmotile rods or coccobacilli
- Ticks, fleas, lice involved in life cycle
- Bacteria enter endothelial cells –>necrosis of vascular lining - vasculitis, vascular leakage, and thrombosis
ii. The Rickettsia Genus
a. Vectors
i. dog ticks
b. Reservoirs
i. dog ticks
ii. rodents normal; humans accidental
c. Transmissions
i. inoculation on accident (rats normal; humans accident)
d. Symptoms
i. Bites have 3-12 day incubation period; Sx flu-like rash; shock
ii. Mortality ~20% in untreated
- Rocky Mountain Spotted Fever (Rickettsia rickettsii) - 1/2 in southeast U.S.
a. Vectors
i. body lice
b. Reservoirs
i. humans
c. Transmissions
i. inoculation + feces –> human skin –> no soap or water –> scratch the microbe into skin –> flu-like symptoms + rash
ii. Reactivation with stress or weakened immuine system
d. Symptoms
i. flu-like + rash
- Rickettsia Prowazekii - Typhus - Worse
- G-
- Intracellular parsites
- Polymorphic - its life cycle includes two different forms
a. elementary bodies
i. time infectious agent that’s taken into cell where it grows inside vacuole into reticulate body
ii. infectious form
b. reticulate bodies
i. the form that multiplies inside cell; turning back into elementary bodies before escaping from the hos cell via lysis.
Chlamydiaceae Family
- Chlamydia Trachomatis
i. Trachoma - attacks mucous membrane of eyes, genitourinary tract, and lungs
- Ocular trachoma - severe infection, deforms eyelid and cornea, preveted by prophylaxis
- Inclusion conjuncitivitis - occurs as baby passes through birth canal
ii. STD - second most prevalent STD; urethritis, cervicitis, salpingitis (PID), infertiligy, scarring
Chlamydia Trachomatis
- no infectious
2. but responsible for the O2 explosion. booyah.
Cyanobacteria
- primary atypical pneumoniae
- pathogen slowly spreads over interior respiratory surfaces,
a. fever
b. chest pain
c. sore throat
i. mycloplasma pneumoniae
- weak sexually transmitted pathogens
ii. mycoplasma genitalium/ureplasma urealyticum
a. No cell walls
b. only cell membranes
c. Sterols in cell membrane (flexibility)
i. HUGE MINORITY HERE IN TERMS OF BACTERIA
d. Surface adhesins allow them to bind strongly to receptors on cells
e. Non-motile
f. Facultative Anaerobes
g. Gram Stain (-) although no peptidoglycan
h. highly pleomorphic
i. Include Mycoplasmas genus
Tenericutes
which domains includes organisms with prokaryotic cell type?
A and B
which domain was first to appear?
A
E coli belongs to hich domain
B
Cells in domain have membrane bound organelles
E
Which domain includes cells that can produce endospores
B
Cells have nucleoid that consists of single chromosome
A & B
Cells in this domain wrap DNA around histones
E
Most of cells in this domain use plasmids to exchance DNA
B+A
euk only yeast
Cells have 80s ribosomes
E
All cells have cell membrane with sterols
E
unique cell membrane with either lipids and a backwards glycerol
A
usually have cell walls of petidoglycan
B
characterized by cell wall includes S layer
A
cells have cell wall that includes outer membrane composed partly of lipopolysaccharide
B
cells can have glycocalyx
A B E
Cells often use undulipodia to move from place to place
E
which scientist boiled and seaked flask of broth failed to grow microbes, yet failed to still generate support for B.G. since vegtative force couldn’t get into the flask?
Lazzaro Spallanzani
Which demonstrated that maggots did not spontaneously generate from something non-living (meat in the case)?
Francesco Redi
Which first showed that fermentation by microbes could result in food spoilage, while also proposing and lending much support to the Germ Theory of Disease?
Pasteur and Koch
Who lended support for the connection between microbes and disease by establishing a set of postulates to confirm the development of a specific disease by a specific microbe?
Robert Koch
Discovery of endospores
Cohn
Proponent for and lended support for Spontaneous Generation
John Needham
Which scientists contributed the most to the development of the growth media and pure culture techniques we used in class?
Koch
Determined that microbes in dust and air were resistant to boiling and came up with the technique of intermittent boiling to eliminate what was later to be confirmed to be endospores?
John Tyndall
Where are endospores typically found?
in soil
When do vegetative cells produce endospores?
When nutrients become depleted
What makes an endospore resistant to chemicals and radiation?
Spore coat
What makes an endospore resistant to heat?
Dipicolinic acid and high calcium ion concentrations
Why do you steam your slide while applying the stain?
To make the stain penetrate the spore coat
When you’ve finished applying stain, what colorshould the endospore be?
Green
vegetative will be pink.
We make smears to
prepare bacteria for staining and to spread out bacteria
preparing a smear for a negative stain involves
air drying the smear
preparing a smear for positive stain involves
air drying AND heat fixing the smear
The advantage of a negative stain is
There is very little cell shrinkage
A smear is ready to be heat fixed if
has been air dried
Heat fixing a smear
helps bacteria absorb the stain
kills the bacteria
helps the bacteria stick to the slide
stains improve
definition
what is being “stained” with negative stain
background
capsule stain is
combination of negative and simple stain
differential stain
A Gram stain differentiates between the bacteria because of differences in bacterial
cell walls
What does mordant do?
combines with crystal violet to form crystalline structure
Which two stains are used for a capsule stain?
simple and negative