Lectures 1 and 2 Flashcards
1
Q
Study of Microbes
A
- all microbes are NOT bad
- humans are more microbe than human cells (3-5 lbs)
- 200 species in mouth
- 100 in gut
2
Q
Microbial Taxonomy: Archaea
A
3 established phyla
3
Q
Microbial Taxonomy: Protista
A
supergroups
4
Q
Microbial Taxonomy: Fungi
A
6 fungal phyla
5
Q
Pathogenicity
A
- host-parasite relationships
- pathogen transmission
- exotoxins, endotoxins
6
Q
members of the microbial world
A
- organisms and acellular entities too small to be clearly seen by the unaided eye
7
Q
members of the microbial world: cellular
(list 4 types)
A
- fungi
- protists
- bacteria
- archaea
8
Q
fungi: examples
A
- yeast
- mold
9
Q
Protists: examples
A
- algae
- slime molds
- protozoa
- triconympha
5.dinenympha - amoeba
10
Q
Bacteria: examples
A
- Bacillus anthracis
- staphylococcus aureas
- e.coli
11
Q
Archaea: examples
A
- methanogens
- halo archaea
12
Q
Members of the microbial world: acellular
(list 4 types)
A
- viruses
- viroids
- satellites
- prions
13
Q
viruses: makeup and examples
A
made of protein and nucleic acid (can be RNA, DNA variants)
1. covid
2. influenza
3. rhinovirus
14
Q
viroids: makeup and example
A
made of RNA
1. plant pathogen
15
Q
satellites: makeup and examples
A
- made of nucleic acid enclosed in a protein shell
- require a helper virus
1. Hep. D
16
Q
Prions: makeup and examples
A
made of proteins
1. mad cow disease
2. CJD
17
Q
Types of microbial cells: 3 domain system
A
bacteria, archaea, eukaryotes
18
Q
Bacteria and Archaea: distinctions from eukaryotes
A
- smaller
- have a nucleoid region
- only microbes
19
Q
Eukaryotes: distinction from bacteria and archaea
A
- have a nucleus
- larger
- have organelles in cytosol (make up cytoplasm)
20
Q
Similarities between bacteria, archaea, and eukaryotes
A
- all have ribosomes, cytoplasm, and a plasma membrane
21
Q
Nomenclature
A
genus, species, strain
example:
E. Coli 0157:H7
E = genus
coli = species
0157.H7 = strain
22
Q
Domain characteristics: bacteria
A
- peptidoglycan
- usually single-celled
- most lack a membrane-bound nucleus
- ubiquitous, can live in extreme environments
23
Q
domain characteristics: archaea
A
- lack peptidoglycan
- unique membrane lipids
- unusual metabolic characteristics
- many live in extreme environments
24
Q
domain characteristics: eukaryotes
A
- membrane bound organelles
- linear DNA
25
Robert Hooke
- published first drawings of microbes
- Micrographia book w/ detailed drawings of fungus and other microorganisms
- bent glass to magnify and view things (idea of a microscope)
26
Antony Van Leeuwenhoex
- constructed simple microscopes
- looked at pond water, blood, feces, etc.
- "animalcules:" first word for microbes
27
Francesco Redi
- discounted spontaneous generation theory (living organisms can develop or arise from nonliving/decomposing matter)
- proved that maggots on decaying meat came from fly eggs, not the meat itself
28
Louis Pasteur
- disproved spontaneous generation in microbes
- pasteurization (heating to kill pathogens)
- rabies and anthrax vaccines
- swan flask (neck traps airborne microbes at base so solution is sterile)
29
Edward Jenner
- pioneer of smallpox vaccine
- used cowpox: took sample and inserted it into 8 y/o boy's arm
- later he was exposed to smallpox and was fine
30
Robert Koch
- anthrax and tuberculosis
- postulates: established link between pathogen and disease
31
development of techniques for studying microbial pathogens
(3 scientists and their creations/discoveries)
Hesse: nutrient agar
Petri: petri dish
Chamberland: bacterial filter and autoclave
32
Dmitri Ivanovsky
- discovered viruses
- studied disease in tobacco plants, leading to discovery
- crushed infected leaves and forced through bacterial filter but found nothing
- brushed on other leaves which caused disease
- figured pathogen must be smaller than bacteria
33
Martinus Beijerinck
- coined term "virus"
34
Alexander Fleming
- realized his body had its own antibacterial power
- nasal mucus
- lysozyme
- 1928 vacation
- bacteria killed by mold (penicillin)
- was unable to purify and concentrate the substance
- in 1940, Florey and Chain purified it, the three of them shared Nobel prize in 1945
35
Preparation and staining of specimens: purpose
- increases visibility of specimen
- accentuates specific features
- preserves specimen
36
prep and staining: fixation
preserves internal and external structures and fixes them in position
- heat fixation (overall morphology)
- chemical fixation (protects fine cellular substructure and morphology)
37
prep and staining: dyes and simple staining
one dye
- divides microorganisms based on their staining properties
- detects presence or absence of structures
- endospores
38
gram staining (differential)
- widely used differential staining procedure
- divides into gram positive and gram negative
- based on differences in cell wall structure, depends on peptidoglycan layer
39
4 steps of preparation and staining
1. fix cells. crystal violet (primary stain) for one minute. water rinse. results in purple stain
2. Iodine for 1 minute. water rinse. results in purple staying
3. alcohol (decolorizer) for 10ish seconds. gram positive is purple, gram negative is colorless
4. safranin (counterstain) for 30-60 seconds. water rinse, blot dry. gram positive stays purple, gram negative is red
40
staining specific structures
1. endospore: double-staining technique
2. capsule staining: 1 negative stain
3. flagella staining: increases thickness of flagella
41
Light microscope varieties
- bright-field
- dark-field
- phase-contrast
- fluorescence
- confocal
42
compound microscope features
2 sets of lenses
- ocular
- objective
43
Bright-field microscope
- dark image against bright background
- several objective lenses
- ideally parfocal
- total magnification
44
parfocal
- when objective is changed, image stays in focus
- ideal, extremely hard to achieve
45
dark-field microscope
- bright image against dark background
- uses a dark stop placed inside condenser, blocks light from shining directly through onto field
- detailed images of unpigmented specimen
- limits: lose magnification, can look grainy
46
phase-contrast
- converts slight variations in cell density into changes in light intensity
- colorless unstained cells are visible
- limits: can create a false halo around specimes
47
Differential Interference Contrast
- similar to phase contrast
- used to observe living cells
- unstained appears colorful, 3D, no halo
48
Fluorescence
- exposes specimen to UV, violent, or blue light
- fluorochromes (dyes)
- ex: staining alive and dead bacteria in different colors
- ex: tagging pathogens
49
electron microscopy: how it works
- electrons replace light as illuminating beam
- allows for study of microbial morphology in great detail (can see viruses)
50
electron microscopy: types
- transmission electron microscopy (TEM)
- scanning electron microscopy (SEM)
51
transmission electron microscopy (TEM)
- electron gun passes electrons through sample (sample must be thin)
- denser regions appear darker
- limitations: takes a long time to process
52
scanning electron microscopy
- electrons reflected from surface of specimen
- realistic 3D image of surface features
53
bacteria: 5 shapes
- cocci
- bacilli
- vibrio
- spirillum
- spirochete
54
cocci: arrangements
- diplococci: 2 attached
- streptococci: chains
- staphylococci: clusters
- tetrad: 4 on perpendicular plane, like a square
- sarcina: 2 tetrads together
55
bacilli (rods)
- single
- sporeformer (spore at one end)
- streptobacillus: chains
- coccobacillus: squished cocci
56
vibrio
comma shaped
57
spirillum
rigid, external flagella at one or both ends
58
spirochete
flexible, endoflagellum
59
bacteria size: average rod
1.5 microns x 6 microns
roughly size of e.coli
60
smallest bacteria
mycoplasma
0.3 microns
61
largest bacteria
- discovered in June 2022
- thiomargarita magnifica
- 1 cm long
62
large bacteria
e. fishelsoni
600 microns
63
bacterial cell structure: organization
- cell envelope
- cytoplasm
- external features
64
cell envelope: plasma membrane
- encompasses cytoplasm
- selectively permeable barrier
- interacts with external environment
- nutrients in, waste out
- transport systems
- metabolic processes (electron transport chain)
65
fluid mosaic model
- lipid bilayer with floating proteins
- amphipathic lipids
- polar (hydrophilic) heads
- nonpolar (hydrophobic) tails
- proteins
66
membranes: characteristics
- lack sterols, but have sterol-like molecules
- hopanoids (stabilize cell wall)
67
cell wall: functions
- maintains shape of bacterium
- protects cell from osmotic lysis
- protects from pathogens
68
peptidoglycan structure
- meshlike polymer
- 2 alternating sugars (NAG & NAM)
- amino acid side chains on NAM
69
gram positive cell wall
- peptidoglycan with teichoic acids
- periplasmic space (narrow, mostly water)
- plasma membrane
70
gram negative cell wall
- 2 periplasmic spaces
- outer membrane
- peptidoglycan
- plasma membrane
71
gram negative cell outer membrane
- lipopolysaccharides
- porins (let water in)
- Braun's lipoprotein
- outer membrane receptor
72
Braun's lipoprotein
- attach peptidoglycan to outer membrane
73
lipopolysaccharides: parts and functions
- lipid a (endotoxin)
- core polysaccharide
- o side chain
- provides stability and protection
- can be pathogenic
