IntroMicro Flashcards
Microbiology
Mycology
Protazoology
Parasitology
Bacteriology
Virology
Archea
Microbes are Everywhere
Microbiology-the study of ________, ___________________________.
Microbes are ____________
Microbes may be ____ or ____
Microbes exist _____, or _____
¡Microbiology-the study of microorganisms, single-celled microscopic organisms.
¡
¡Microbes are independent life-forms
¡
¡ Microbes may be prokaryotic, or eukaryotic
¡
¡Microbes exist free living in the environment, or colonize a host.
It’s a Microbial World
Microbes live in large numbers in ___ and ____
____ ____, and are important for ____ ____
Saprophytic bacteria
¡Microbes live in large numbers in soil and water
¡
¡Metabolically diverse, and are important for nutrient cycling
Break down dead material
The original life on Earth
¡Microbes are the __________________
¡Bacteria ________________.
¡Microbes are the oldest forms of life on Earth
¡Bacteria created an oxygenated atmosphere
The Microbes Within
¡Bacteria can act as____
_____
____
____
____
_____: ____
¡Bacteria can act as symbionts:
§Other microbes
§Plants
§Invertebrates
§Insects
§Animals
▪Ruminants
It’s the Microbiome! = _____= ______
¡Important for ____
¡Can cause____
_____
§Ex)
¡The Human Flora
¡The bacteria that live on us and in us
¡Important for health
¡Can cause disease
¡“Balance”
§Taking antibiotics for an infection
§Destroying the gut microbiome
Bacteriology
Procaryotes vs Eucaryotes
Size:
much smaller than eukaryotes, which are
No
Size: 0.1-3 microm
much smaller than eukaryotes, which are > 5 microm
No membrane-bound organelles
no nucleus, mito-chondria, endoplasmic reticulum, Golgi, etc., which are characteristic of eukaryotes
Bacterial genomes
- ____(most eukaryotes are ____)
- typically ___ chromosome of ____-stranded, ________, _____ DNA
- not contained by a ____ ____ as in eukaryotes
- DNA is___________ in an area called the ____
- organized in ____ coiled loops due to associated ___ and ____
- haploid (most eukaryotes are diploid)
- typically one chromosome of double-stranded, super-coiled, circular DNA
- not contained by a nuclear membrane as in eukaryotes
- DNA is free in cytoplasm in an area called the nucleoid
- organized in 40-50 coiled loops due to associated RNA and proteins
Bacteria may contain plasmids
____ ____ ___-_____ DNA
•may confer ____ ____
_____/____ genes
•–i.e. ___ ____
- small circular extra-chromosomal DNA
- may confer antibiotic resistance
- toxicity/virulence genes
- –i.e. anthrax toxins
Bacterial genes
•do not contain ____
_____: _________________and ______________
•_________: ________________
Bacterial genes
•do not contain introns
•
•operons: functionally related genes tandemly arrayed and co-transcribed to yield a polycistronic mRNA
•
•transcription-translation coupling: translation begins as mRNA being transcribed
•
•
Bacterial Cell Membrane
Cytoplasmic membrane
▪Lipid bilayer with_______________
▪Forms a ___ ___ between the____ and ____
▪____/____
▪____ of ____
- _____
- _______
- _______
▪Gram + bacteria have ___ membrane, Gram – bacteria have ___
§Cytoplasmic membrane
▪Lipid bilayer with embedded membrane proteins
▪Forms a selective barrier between the cytoplasm and environment
▪Diffusion/Transport
▪Generation of gradients
Proton motive force
Concentration of nutrients
Exclusion of wastes/toxins
▪Gram + bacteria have one membrane, Gram – bacteria have two
Cell Wall
Cell Wall
- Located just outside the __________
- Gives bacterium ___ and ___
- Composed of ____
- •Only found in ____
- Protects against ____ ____
- Different_____ in Gram – and Gram + bacteria
Cell Wall
- Located just outside the cytoplasmic membrane
- Gives bacterium rigidity and shape
- Composed of peptidoglycan
- Only found in prokaryotes
- Protects against osmotic lysis
- Different thickness in Gram – and Gram + bacteria
Cell Wall Peptidoglycan
•____ ____ chains ___-____ by ___ ____ ____
- Polysaccharide chain:
- repeating ____ of _______ and________
- cleaved by ___ ____yielding a ____ which____ unless _____ ___
- Cross-linking peptides
- _________
- always linked to ___ ___via ____
- ____ ___-____ _______ catalyze _____________
- •called _______________ because they are targets for___ and other ______
•
•Linear polysaccharide chains cross-linked by short peptide chains
•
•Polysaccharide chain:
•repeating disaccharide of N-acetylmuramic acid (M) and N-acetylglucosamine (G)
•cleaved by host lysozyme yielding a spheroplast which lyses unless osmotically stabilized
•
•Cross-linking peptides
•vary with species
•always linked to carbohydrate chains via muramic acid (M).
•Cytoplasmic membrane-bound transpeptidases catalyze the cross-linking reactions
•called penicillin-binding proteins (PBPs) because they are targets for penicillin and other b-lactam antibiotics.
•
Gram Positive Bacteria
- ____ _____ wall (__-__Å)
- consists mainly of ________
- also contains _____ and _____
- •polymers of ____ (or ____) and ____
- •teichoic acid is _____________
- •lipoteichoic acid is _________________ by _________________
•thick multilayer wall (150-500 Å)
•consists mainly of peptidoglycan
•also contains teichoic and lipoteichoic acids
•polymers of glycerol (or ribitol) and phosphate
•teichoic acid is cross-linked to peptidoglycan
•lipoteichoic acid is anchored to the cytoplasmic membrane by covalently attached fatty acid
¡
Gram Negative Bacteria
¡Peptidoglycan layer
____;
lies________
¡Outer membrane
•lies ____________
•contains ___ ____ ____ ____, which allow ________________
•_________ constitutes the ___ ___
•
¡Periplasmic space
•bounded by _____ and ____
•contains a variety of ____ ____s including ____ _____ (e.g., ______)
•
¡
¡Peptidoglycan layer
•thin; lies outside the cytoplasmic membrane
•
¡Outer membrane
•lies outside the peptidoglycan layer
•contains pore-forming porin proteins, which allow entry of small hydrophilic molecules
•lipopolysaccharide (LPS) constitutes its outer leaflet
•
¡Periplasmic space
•bounded by cytoplasmic and outer membranes
•contains a variety of hydrolytic enzymes including virulence factors (e.g., collagenase)
•
¡
Lipopolysaccharide (LPS)
- occurs in the ___ ____ of the___ ____of Gram ___ bacteria.
- also known as ____
- a powerful ____ of the ____ ____
- endotoxin activity due to ___ ___
- O-antigens
- •___ ____
- •useful for _______ _____
- occurs in the outer leaflet of the outer membrane of Gram(-) bacteria.
- also known as endotoxin.
- a powerful stimulator of the immune response
- endotoxin activity due to lipid A
- O-antigens
- strain-specific
- useful for serologic identification
Cell Wall: Peptidoglycan & the Gram Stain
•Gram(+) bacteria have a ____peptidoglycan cell wall, which ___________ (a __________complex)
•
•Gram(–) bacteria have a ____ peptidoglycan layer, which allows the stain to be ____ ____away
•
•
•Gram(+) bacteria have a thick peptidoglycan cell wall, which traps the Gram stain (a crystal violet-iodine complex)
•
•Gram(–) bacteria have a thin peptidoglycan layer, which allows the stain to be readily washed away
•
•
External Appendages
___
____
_____
____
¡
§ Flagella
§ Pili
§Fimbriae
§Capsule
§
¡
¡
Cell Wall Morphology
___
____
____
____
____ and ___
____
Bacterial Reproduction and Growth
____ reprod via ____ ____
____ offspring
Cell division
- asexual reproduction via binary fission
- Clonal offspring
Genetic Transfer
¡Transfer of DNA between bacteria occurs ____________
Types:
¡Bacteria can share _____________by genetic transfer (___ ___)
¡Transfer of DNA between bacteria occurs separately from cell division
§Transformation
§Transduction
§Conjugation
¡Bacteria can share favorable new genes by genetic transfer (antibiotic resistance)
Growth Phases
- Lag phase:
- period of ____ to ____ ____
•Log or exponential phase:
____ ___
___ ____ is characteristic of the ___
- Stationary phase:
- ___ or____become ____ or ____ metabollic products _____
- cell division rate __ cell death rate
- Death phase:
- cell death rate_ cell division rate
¡
•Lag phase:
•period of adaptation to new condition
•
•Log or exponential phase:
•optimal growth
•doubling time is characteristic of the strain
•
•Stationary phase:
•nutrients or oxygen become limiting or toxic metabolic products accumulate
•cell division rate = cell death rate
•
•Death phase:
•cell death rate > cell division rate
•
¡
Growth Rate is Dependent on Environmental Conditions
¡Bacteria occupy diverse habitats, and have ____ ____ of ___ and ____ for ____
Resources: __ ___ ____ _____ _____ ____. macro, micro, donor, acceptor, C N
Conditions: ___ ___ ___ ___ ___ ____ light T pH osmolarity O2water
¡Bacteria occupy diverse habitats, and have favored sources of energy and conditions for growth
Resources: C, N, macronutrients, micronutrients, O2 (e acceptor), inorganic e donor
Conditions: T, pH, water, O2, Light, Osmotic conditions
Bacterial Oxygen Tolerance
- Strict aerobes
- restricted to using ___ ____
- can only use ___ as ______
- lack ________
•Facultative anaerobes
•capable of _____ ____in the presence of O2
•use either ____ or _____in its absence
•
•Strict anaerobes
•lack ___ ___ ____
•depend on ____ to generate energy
•______ ____(some ___ ____) in ___ usually due to lack of _____ ____ and/or ____
•
•Aerotolerant anaerobes
•lack ___ ___ ____
•depend on ____
•tolerate ___ but __________, have ___ and/or ____
•
•Microaerophilic bacteria
•require a ____ amount of oxygen, but too much is____
•
•Strict aerobes
•restricted to using aerobic respiration
•can only use O2 as final electron acceptor
•lack enzymes for fermentation
•
•Facultative anaerobes
•capable of aerobic respiration in the presence of O2
•use either anaerobic respiration or fermentation in its absence
•
•Strict anaerobes
•lack respiratory chain enzymes
•depend on fermentation to generate energy
•cannot grow (some cannot survive) in O2 usually due to lack of superoxide dismutase(SOD) and/or catalase
•
•Aerotolerant anaerobes
•lack respiratory chain enzymes
•depend on fermentation
•tolerate O2 but do not use it, have catalase and/or SOD
•
•Microaerophilic bacteria
•require a small amount of oxygen, but too much is toxic.
•
There are more bacterial cells in the human body
than there are human cells.
~10__ human cells
~10__ bacterial cells
There are more bacterial cells in the human body
than there are human cells.
~1013 human cells
~1014 bacterial cells
Host-Microbe Interactions
___-___
not _____
___ ____
___ the host
___ ____
___ associated, with no _____
Opportunistic pathogens
Can cause ___ in ___ ____
Frank pathogens
Can cause ___ in ___ ____
nFree-living
nnot found in association with a host
n
nSymbiotic organisms
nbenefit the host
n
nCommensal organisms
n host-associated, with no apparent negative effects
n
nOpportunistic pathogens
nCan cause disease in compromised hosts
n
nFrank pathogens
nCan cause disease in immunocompetent hosts
Human Symbiotic Bacteria
____ bacteria participate in ____
___ ____ broken down into ____ and ___ ____ ___
____ of __ ____ in gut ___
¡Gut bacteria participate in digestion
§Complex carbohydrates broken down into mono-saccharides and volatile fatty acids
§“Maturing” of gene expression in gut mucosa
Human Commensal Bacteria
__________
“___ ____”
§No ______
¡May protect the host by ______ ___ ___ by _____.
¡Most bacteria that colonize humans are considered commensal
§“Normal Flora”
§No direct measurable benefit
¡May protect the host by “excluding” pathogenic bacteria by competition
Opportunistic pathogens
¡Members of the ____ ____ may become pathogenic
§Host defenses are ____
- ▪Enter normally __ ____ through___
- ▪Host___ ____are compromised
- ____
- ▪____ host physiology
¡Members of the normal flora may become pathogenic
§Host defenses are compromised
▪Enter normally sterile tissues through injury
▪Host immune defenses are compromised
▪Neutropenia
▪Imbalanced host physiology
What is a (frank) pathogen?
¡Pathogenesis – _________________________________.
§ Example – ___ ____ is a pathogen.
¡Virulence – the ability of a ___ ____ to ____ ___
§ ____ Dose (_D50) – dose required to ___ ___ in 50% of hosts
§ ___ Dose (_D50) – dose required to ____ ___in 50% of hosts
§ Example – is a virulent strain of Borrelia burgdorferi
§
¡Many examples of frank pathogens are transmitted from other “_____” or ____
___ ___
___ ___
___ ___
¡
¡Pathogenesis – the ability of an organism (e.g. a bacterial species) to cause disease
§ Example – Bacillus anthracis is a pathogen.
¡Virulence – the ability of a given strain to cause disease
§ Infectious Dose (ID50) – dose required to cause infection in 50% of hosts
§ Lethal Dose (LD50) – dose required to cause death in 50% of hosts
§ Example – B31 is a virulent strain of Borrelia burgdorferi
§
¡Many examples of frank pathogens are transmitted from other “reservoirs” or sources.
§Environmental sources
§Animal flora
§Carrier hosts (human)
¡
Kochs postulates
(1884)
¡The microorganism must be found in all organisms suffering from the disease, but not in healthy organisms.
¡
¡The microorganism must be isolated from a diseased organism and grown in pure culture.
¡
¡The cultured microorganism should cause disease when introduced into a healthy organism.
¡
¡The microorganism must be re-isolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.
¡
Molecular Kochs postulates
(for identifying virulence factors)
Dr. Stanley Falkow, 1988
¡The virulence property and associated gene(s) should be found in pathogenic members of a genus or pathogenic strains of a species.
¡Inactivation of the gene(s) associated with the suspected virulence trait should result in a measurable loss in pathogenicity or virulence.
¡Reversion of the mutation or complementation with an active copy of the gene should restore pathogenicity or virulence.
Mechanisms of Pathogenesis
- A
- I
- P
- ___ and ____
- ¨___ ___
- ¨___ ____ ___
- ___ ____ ____ ( ___ )
- ___ and ____
- E
- ___ of ___ ____
- E
- R
nAttachment (adherence)
nInvasion of host tissues
nProduction of
nToxins and enzymes
¨Degradative enzymes
¨Cell signalling toxins
¨Cell metabolism byproducts (butyrate)
nEndotoxin (lipopolysaccharide)
nInduction of excessive inflammation
nEvasion of immune clearance
nResistance to antibiotics
n
Pathogenic behaviors
E
A
I
C and G
T___ and I ____
T
exposure
adherance
invasion
colonization/growth–> toxcity and invasiveness
Tissue damage
Endotoxin = Lipopolysaccharide (LPS)
¡Major component in the outer membrane of Gram-negative bacteria
§Active component = ___ + ___= ____
¡Effects
____, ____
____
_____ of ___ ____
___, ___
§
¡Major component in the outer membrane of Gram-negative bacteria
§Active component =
lipid + core = Lipid A
¡Effects
§Fever, chills
§Hemorrhage
§Loss of blood pressure
§Shock, death
§
Infectious Diseases Equation
Infection = Number Organisms x Virulence/ Resistance of Host
Host factors affecting infection
- I___H ___ D____
- P____ b___- ____, ___ ___
- p____ c____: ___, ____
- p____ c____- ___ ___ and ____ ___
- e____- ____ in ___ and _____
- G___ H___ and N____
- A___ – ___ and ____ are more susceptible
- M____ affects ___ ___
- C____ c____, D______, t____, etc.
- S___
- G____ f____
- I____ d____
*
- I____ d____
¡Innate Host defenses
nPhysical barriers -Skin, mucous membranes
nPhagocytic cells -Macrophages, neutrophils
nProtective chemicals- Stomach acid, bile salts
nEnzymes- Lysozyme in saliva, small intestine
¡General health and nutrition
§Age – very young and very old are more susceptible
§Malnutrition affects immune response
§Cancer chemotherapy, diabetes, trauma, etc.
§Stress
¡Genetic factors
§Inherited defects
¡
¡
Health and Disease in BalanceS
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