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Oral Bio > IntroMicro > Flashcards

IntroMicro Flashcards

1
Q

Microbiology

A

Mycology

Protazoology

Parasitology

Bacteriology

Virology

Archea

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2
Q

Microbes are Everywhere

Microbiology-the study of ________, ___________________________.

Microbes are ____________

Microbes may be ____ or ____

Microbes exist _____, or _____

A

¡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.

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3
Q

It’s a Microbial World

Microbes live in large numbers in ___ and ____

____ ____, and are important for ____ ____

Saprophytic bacteria

A

¡Microbes live in large numbers in soil and water
¡
¡Metabolically diverse, and are important for nutrient cycling

Break down dead material

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4
Q

The original life on Earth

¡Microbes are the __________________
¡Bacteria ________________.

A

¡Microbes are the oldest forms of life on Earth
¡Bacteria created an oxygenated atmosphere

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5
Q

The Microbes Within

¡Bacteria can act as____
_____

____
____
____
_____: ____

A

¡Bacteria can act as symbionts:
§Other microbes
§Plants
§Invertebrates
§Insects
§Animals
▪Ruminants

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6
Q

It’s the Microbiome! = _____= ______

¡Important for ____
¡Can cause____
_____
§Ex)

A

¡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

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7
Q

Bacteriology

A
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8
Q

Procaryotes vs Eucaryotes

Size:

much smaller than eukaryotes, which are

No

A

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

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9
Q

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 ____
A
  • 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
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10
Q

Bacteria may contain plasmids

____ ____ ___-_____ DNA
•may confer ____ ____
_____/____ genes
•–i.e. ___ ____

A
  • small circular extra-chromosomal DNA
  • may confer antibiotic resistance
  • toxicity/virulence genes
  • –i.e. anthrax toxins
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11
Q

Bacterial genes

•do not contain ____

_____: _________________and ______________
•_________: ________________

A

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
•
•

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12
Q

Bacterial Cell Membrane
Cytoplasmic membrane
▪Lipid bilayer with_______________
▪Forms a ___ ___ between the____ and ____
▪____/____
▪____ of ____

  • ­_____
  • ­_______
  • ­_______

▪Gram + bacteria have ___ membrane, Gram – bacteria have ___
­

A

§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
­

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13
Q

Cell Wall

Cell Wall

  • Located just outside the __________
  • Gives bacterium ___ and ___
  • Composed of ____
  • •Only found in ____
  • Protects against ____ ____
  • Different_____ in Gram – and Gram + bacteria
A

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
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14
Q

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 ______

•

A

•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.
•

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15
Q

Gram Positive Bacteria

  • ____ _____ wall (__-__Å)
  • consists mainly of ________
  • also contains _____ and _____
  • •polymers of ____ (or ____) and ____
  • •teichoic acid is _____________
  • •lipoteichoic acid is _________________ by _________________
A

•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
¡

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16
Q

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., ______)
•
¡

A

¡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)
•
¡

17
Q

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 _______ _____
A
  • 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
18
Q

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
•
•

A

•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
•
•

19
Q

External Appendages

___

____
_____
____

A

¡
§ Flagella
§ Pili
§Fimbriae
§Capsule
§
¡
¡

20
Q

Cell Wall Morphology

___
____
____
____
____ and ___

____

A
21
Q

Bacterial Reproduction and Growth

____ reprod via ____ ____
____ offspring

A

Cell division

  • asexual reproduction via binary fission
  • Clonal offspring
22
Q

Genetic Transfer

¡Transfer of DNA between bacteria occurs ____________
Types:

¡Bacteria can share _____________by genetic transfer (___ ___)

A

¡Transfer of DNA between bacteria occurs separately from cell division
§Transformation
§Transduction
§Conjugation
¡Bacteria can share favorable new genes by genetic transfer (antibiotic resistance)

23
Q

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
A

¡
•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
•
¡

24
Q

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

A

¡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

25
Q

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____
•

A

•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.
•

26
Q

There are more bacterial cells in the human body
than there are human cells.

~10__ human cells

~10__ bacterial cells

A

There are more bacterial cells in the human body
than there are human cells.

~1013 human cells

~1014 bacterial cells

27
Q

Host-Microbe Interactions

___-___

not _____

___ ____

___ the host

___ ____
___ associated, with no _____

Opportunistic pathogens
Can cause ___ in ___ ____

Frank pathogens
Can cause ___ in ___ ____

A

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

28
Q

Human Symbiotic Bacteria

____ bacteria participate in ____
___ ____ broken down into ____ and ___ ____ ___
____ of __ ____ in gut ___

A

¡Gut bacteria participate in digestion
§Complex carbohydrates broken down into mono-saccharides and volatile fatty acids
§“Maturing” of gene expression in gut mucosa

29
Q

Human Commensal Bacteria

__________
“___ ____”
§No ______
¡May protect the host by ______ ___ ___ by _____.

A

¡Most bacteria that colonize humans are considered commensal
§“Normal Flora”
§No direct measurable benefit
¡May protect the host by “excluding” pathogenic bacteria by competition

30
Q

Opportunistic pathogens

¡Members of the ____ ____ may become pathogenic
§Host defenses are ____

  • ▪Enter normally __ ____ through___
  • ▪Host___ ____are compromised
    • ____
  • ▪____ host physiology
A

¡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

31
Q

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 ____
___ ___

___ ___
___ ___
¡

A

¡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)
¡

32
Q

Kochs postulates

(1884)

A

¡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.
¡

33
Q

Molecular Kochs postulates
(for identifying virulence factors)
Dr. Stanley Falkow, 1988

A

¡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.

34
Q

Mechanisms of Pathogenesis

  • A
  • I
  • P
    • ___ and ____
      • ¨___ ___
      • ¨___ ____ ___
      • ___ ____ ____ ( ___ )
  • E
    • ___ of ___ ____
  • E
  • R
A

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

35
Q

Pathogenic behaviors

E
A
I
C and G
T___ and I ____

T

A

exposure

adherance

invasion

colonization/growth–> toxcity and invasiveness

Tissue damage

36
Q

Endotoxin = Lipopolysaccharide (LPS)

¡Major component in the outer membrane of Gram-negative bacteria
§Active component = ___ + ___= ____

¡Effects
____, ____

____

_____ of ___ ____

___, ___
§

A

¡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
§

37
Q

Infectious Diseases Equation

A

Infection = Number Organisms x Virulence/ Resistance of Host

38
Q

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____
      *
A

¡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
¡
¡

39
Q

Health and Disease in BalanceS

A

Slide 43

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