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microbiology > microorganisms and the human body > Flashcards

microorganisms and the human body Flashcards

1
Q

Microorganisms and the human body

A

bacteria, viruses, fungi, protozoa= microbiome
bacteria is vast majority
helminths (worms)

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2
Q

Parasitic organisms

A

Parasitic organisms

Symbionts that harm or live at the expense of their host

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3
Q

Commensal organisms

A

Normal microbiota - microbes frequently found on or within

the bodies of healthy persons

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4
Q

Infection

A

–growth and multiplication of parasite on or within host

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5
Q

Infectious disease

A

–disease resulting from infection

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6
Q

Pathogen/types

A

–any parasitic organism that causes infectious disease
–primary (frank) pathogen – causes disease by direct interaction with host
–opportunistic pathogen – causes disease only under certain circumstance

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7
Q

Pathogenicity

A

Pathogenicity

–ability of parasite to cause disease

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8
Q

Virulence factor

A
  • any component of a pathogenic microbe that is required for

or that potentiates its ability to cause disease

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9
Q

Steps in an infectious disease

A 
encounter 
entry
spread 
multiplication 
damage 
outcome
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10
Q

ways encounter of infectious diseases

A

Exogenous, Endogenous, or Congenital

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11
Q

ways of pathogen entry

A

Ingress: inhalation, ingestion
Penetration: microbes pass through epithelia directly (via
attachment and internalization), insect bites, cuts
and wounds, organ transplants and blood
transfusions

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12
Q

spread of infection

A

lateral propagation (localized) versus dissemination (systemic infection)
anatomical factors
active participation by microbes with motility

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13
Q

Multiplication of pathogen

A 
environmental factors (e.g. temperature) can stimulate division 
subversion of host defenses
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14
Q

damage from infection

A

direct damage from pathogen or from immune response

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15
Q

infection outcomes

A

microbe wins, host wins, or they learn to coexist

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16
Q

Normal Microbiota

when does it form?

A

microbes frequently found on or within the bodies of healthy persons\ =commensal organisms
Colonization by bacteria occurs rapidly after birth.
Thousands of bacterial species are part of the normal flora

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17
Q

The Human Microbiome

A

the collection of all the microorganisms living in association with the human body
eukaryotes, archaea, bacteria and viruses

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18
Q

bacteria vs human cell anbundance

A

Bacteria in an average human body number ten times more than human cells
contain a total of about 1000 more genes than are present in the human genome
because of their small size bacteria make up only about 1-3% of our body mass
2 to 6 pounds of bacteria in a 200-pound adult

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19
Q

bacteria of the microbiome roles

A

essential for maintaining health

produce some vitamins we cant make

extract nutrients from food

teach our immune systems how to recognize dangerous invaders

produce helpful anti-inflammatory compounds that fight off other disease-causing microbes

occupy space to crowd out disease-causing microbes

detoxification of carcinogens but sometimes are the source of carcinogen production

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20
Q

changes to the human microbiome

A

Changes in the composition of our microbiomes correlate with numerous disease states, source of infection
manipulation of these communities could be used to treat disease

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21
Q

Locations in body with largest amounts of bacteria

A 
skin (especially moist areas)
respiratory tract (nose and oropharynx)
digestive tract (mouth and large intestine)
urinary tract (anterior parts of urethra)
genital system (vagina)
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22
Q

Other body locations have small numbers of bacteria

A

Remainder of respiratory and digestive tracts

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23
Q

Some body locations are sterile.

A

blood, cerebrospinal fluid, synovial fluid, deep tissues

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24
Q

Transient vs. resident organisms

A

transient- somtimes present

resident- always present

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25
Q

pathogenicity and virulence also depend on?

A

Pathogenicity/virulence also depends on the host

Definition of pathogen not so certain

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26
Q

Examples where normal flora are source of infection:

A

periodontitis - overgrowth of particular bacteria in gingival crevices

pneumonia - defenses lowered and microaspirations of pneumococci.

catheter-associated infections - staphylococci

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27
Q

Oral flora includes

A 
bacteria (and archeae)
fungi
protozoa (eukaryotes)
viruses
~700 different species of bacteria are estimated to
be present in the oral cavity
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28
Q

Oral habitats

A 
buccal mucosa
dorsum of tongue
tooth surfaces
crevicular epithelium
dental appliances
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29
Q

Issues for microbial cells

A

Nutritional fluxes
Maintaining occupancy
Resistance to damage

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30
Q

Factors modulating oral microbial growth

A 
anatomical features that create areas that are difficult to clean
saliva
GCF 
microbial factors 
pH
redox potential 
antimicrobial therapy 
diet 
iatrogenic factors
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31
Q

Factors modulating oral microbial growth- anatomical features that create areas that aredifficult to clean

A

shape and topography of teeth e.g. fissures
malalignment of teeth
poor quality of restorations (e.g. fillings and bridges)
non-keratinized sulcular epithelium

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32
Q

Factors modulating oral microbial growth-saliva
components?
functions?

A

mixture of inorganic ions, organic constituents, proteins, glycoproteins (e.g. mucin)
promotes adhesion of bacteria on tooth surfaces, organic components form a coating on tooth surfaces= salivary pellicle
source of food
promotes aggregation of bacteria, facilitating their clearance from mouth
inhibits growth of microbes by non-specific defensefactors
maintains pH

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33
Q

Factors modulating oral microbial growth-

gingival crevicular fluid

A 
flushing microbes out of crevice
source of nutrients for microbes
maintains pH
specific and non-specific defense factors
phagocytosis- neutrophils main phagocyte
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34
Q

Factors modulating oral microbial growth

microbial factors

A 
competition for adhesion receptors
toxin production
metabolic end products
negative vs. positive effects
congregation
35
Q

Factors modulating oral microbial growth-local pH, how can it vary

A

will vary with diet as a result of bacterial metabolism

36
Q

3 domains of life

A

eukaryotes, bacteria and arachea

37
Q

Prokaryotic Cell Membrane
required?
encompasses?
possible internal membranes?

A
  • membranes are an absolute requirement for all living organisms
  • plasma membrane encompasses the cytoplasm
  • some prokaryotes also have internal membrane systems
38
Q 
The Plasma Membrane
contains?
orgainzed?
symmetry?
flex/dynamic?
A

• contains lipids and proteins
– lipids usually form a bilayer
– proteins are embedded in or associated with lipids
• highly organized, asymmetric, flexible, and dynamic

39
Q

The asymmetry of most

membrane lipids

A 
• polar ends
– interact with water
– hydrophilic
• nonpolar ends
– insoluble in water
– hydrophobic
40
Q

other mem lipids

A

euk-cholesterol

bac- hopanoid

41
Q

Membrane proteins

A

peripheral proteins
– loosely associated with the membrane and
easily removed
• integral proteins
– embedded within the membrane and not easily
removed

42
Q

Functions of the plasma

membrane

A

• separation of cell from its environment

• selectively permeable barrier
– some molecules are allowed to pass into or out of the cell
– transport systems aid in the movement of molecules

location of crucial metabolic processes

• detection of and response to chemicals inc surroundings with the aid of special receptor molecules in the membrane

43
Q

Inclusion Bodies, membrane?

A

• granules of organic or inorganic material
that are stockpiled by the cell for future use

• some are enclosed by a single-layered
membrane
– membranes vary in composition
– some made of proteins; others contain lipids

44
Q

Ribosomes

A 
• complex structures consisting of protein and RNA
• sites of protein synthesis
• smaller than eucaryotic ribosomes
– prokaryotic ribosomes Þ 70S
– eukaryotic ribosomes Þ 80S
45
Q

The Nucleoid

A

• irregularly shapedregion
• location of chromosome (1, circular shaped)
– usually 1/cell
• not membranembound

46
Q

nucleoid in actively growing cells

A 
In actively
growing cells,
the nucleoid
has projections;
these probably
contain DNA
being actively
transcribed
47
Q

The prokaryotic chromosome

proteins with it?

A 
• a closed circular, double-stranded DNA
molecule
• looped and coiled extensively
• nucleoid proteins probably aid in folding
– nucleoid proteins differ from histone
48
Q

Unusual nucleoids

A 
• some prokaryotes have > 1 chromosome
• some prokaryotes have chromosomes
composed of linear double-stranded DNA
• a few genera have membrane-delimited
nucleoids
49
Q

Plasmids
relation to chromo?
required?
may carry?

A

• usually small, closed circular DNA molecules
• exist and replicate independently of chromosome
• not required for growth and reproduction
• may carry genes that confer selective
advantage (e.g., drug resistance)

50
Q

The Prokaryotic Cell Wall

A

• rigid structure that lies just outside the plasma membrane

51
Q

Functions of cell wall

A
  • shape
  • protects from osmotic lysis
  • contribute to pathogenicity
  • protect cell from toxic substances
52
Q

Cell walls of Bacteria classes

staining colors?

A

• Bacteria are divided into two major groups based on the response to Gram-stain procedure.
– gram-positive bacteria stain purple
– gram-negative bacteria stain pink
• staining reaction due to cell wall structure

53
Q

gram positive cell wall

A
54
Q

gram negative cell wall

A
55
Q

Periplasmic space

A 
• gap between plasma membrane and cell
wall (gram-positive bacteria) or between
plasma membrane and outer membrane
(gram-negative bacteria)
• periplasm
– substance that occupies periplasmic space
56
Q

Periplasmic enzymes
found in what bacteria class?
functions?

A 
• found in periplasm of gram-negative bacteria
• some of their functions
– nutrient acquisition
– electron transport
– peptidoglycan synthesis
– modification of toxic compounds
57
Q

Exoenzymes

A

• secreted by gram-positive bacteria
• perform many of the same functions that
periplasmic enzymes do for gram-negative
bacteria

58
Q

Peptidoglycan Structure

A
  • important component of both gram-positive and gram-negative bacteria
  • polysaccharide formed from peptidoglycan subunits
  • two alternating sugars form backbone (NAG and NAM) that connects to peptide which may contain some AA not found in proteins
59
Q

gram-negative vs gram-positive peptidoglycan linkages

A

gram -: D-ALA to DAP to form cross links
Gram +: peptide interbridge with Gly
both form the meshwork of peptidoglycan

60
Q

Gram-Positive Cell Walls

•additional content?

A
  • composed primarily of peptidoglycan

* also contain large amounts of teichoic acids, lipotechoic acid may anchor the peptidoglycan to the plasma membrane

61
Q

teichoic acids composition

A

• polymers of glycerol
or ribitol joined by
phosphate groups

62
Q

Gram-Negative Cell Walls

A
  • consist of a thin layer of peptidoglycan surrounded by an outer membrane
  • outer membrane composed of lipids, lipoproteins, and lipopolysaccharide (LPS)
  • no teichoic acids
63
Q

Important connections of gram - walls

A

• Braun’s lipoproteins connect outer membrane to peptidoglycan

• Adhesion sites
– sites of direct contact (possibly true membrane fusions) between plasma membrane and outer membrane
– substances may move directly into cell through adhesion sites

64
Q

Lipopolysaccharides (LPSs) components

A

• consist of three parts
– lipid A
– core polysaccharide
– O side chain (O antigen)

65
Q

Importance of LPS

A
  • protection from host defenses (O antigen)
  • contributes to negative charge on cell surface (core polysaccharide)
  • helps stabilize outer membrane structure (lipid A)
  • can act as an endotoxin (lipid A)
66
Q

Other characteristics of outer membrane

A

• more permeable than plasma membrane due to presence of porin proteins and transporter proteins
– porin proteins form channels through which small molecules (600-700 daltons) can pass

67
Q

Components External to Cell Wall

A

Capsules, Slime Layers, and SLayers

68
Q

Types of material lying outside the cell wall

A

– capsules
• usually composed of polysaccharides
• well organized and not easily removed from cell

– slime layers
• similar to capsules except diffuse, unorganized and
easily removed

69
Q

• glycocalyx

A

– network of polysaccharides extending from the
surface of the cell
– a capsule or slime layer composed of
polysaccharides can also be referred to as a
glycocalyx

70
Q

functions of layers external to the cell wall

A
  • protection from viral infection or predation by bacteria
  • protection from chemicals in environment (e.g., detergents)
  • motility of gliding bacteria
  • protection against osmotic stres
71
Q

Pili and Fimbriae
size compared
functions?
made of?

A 
• fimbriae
– short, thin, hairlike, proteinaceous appendages
• up to 1,000/cell
– mediate attachment to surfaces
• sex pili
– similar to fimbriae except longer, thicker, and
less numerous (1-10/cell)
– required for mating (DNA transfer)
72
Q

Flagella and Motility

A

required for motility

73
Q

Patterns of flagellum arrangement

A
  • monotrichous – one flagellum
  • polar flagellum – flagellum at end of cell
  • amphitrichous – one flagellum at each end of cell
  • lophotrichous – cluster of flagella at one or both ends
  • peritrichous – spread over entire surface of cell
74
Q

Flagellar Ultrastructure

A 
3 parts
– filament
– basal body= anchor 
– hook= bends structure for motion 
DIFFERENT IN GRAM +/-
75
Q

The Bacterial Endospore, resistant to?

A 
• formed by some bacteria
• dormant
• resistant to numerous environmental
conditions
– heat
– radiation
– chemicals
– desiccation
76
Q

An Overview of Eukaryotic Cell Structure

A 
• membrane-delimited nuclei
• membrane-bound organelles that
perform specific functions
• more structurally complex than
prokaryotic cell
• generally larger than prokaryotic
cel
77
Q

The Endoplasmic Reticulum

what can be made here?

A

irregular network of branching and fusing membranous tubules and flattened sacs (cisternae – s.,cisterna)

• rough (granular) ER
– ribosomes attached
– synthesis of secreted proteins by ER-associated ribosomes

• smooth (agranular) ER
– devoid of ribosomes
– synthesis of lipids by ER-associated enzymes

• Functions of ER
– transports proteins, lipids, and other materials within cell
– major site of cell membrane synthesis
– synthesis of lysosomes

78
Q

The Golgi Apparatus

A

• membranous organelle made of cisternae stacked on each other
• dictyosomes– stacks of cisternae
• involved in modification,packaging, and secretion of materials
cis- associated with ER
trans-distal portion

79
Q

Lysosomes

A

– membrane-bound vesicles

– contain hydrolytic enzymes needed for digestion of macromolecules

80
Q

• endocytosis

A

– uptake of solutes or particles by enclosing them in vesicles or vacuoles pinched off from the plasma membrane
• Phagocytosis – particles or bacterial cells
• Pinocytosis -solutes

81
Q

Mitochondria is the site of?

A

Mitochondria
• site of tricarboxylic acid cycle activity
• site where ATP is generated by electron transport and oxidative phosphorylation

82
Q

Mitochondrial structure/ contents of different areas

A

• outer membrane

• inner membrane
– highly folded to form cristae (s., crista)
– location of enzymes and electron carriers for electron transport and oxidative phosphorylation

• matrix
– contains ribosomes, mitochondrial DNA, and large calcium phosphate granules
– contains enzymes of the tricarboxylic acid cycle and the β- oxidation pathway for fatty acids

83
Q

The Nucleus, contents/components?

A

• nucleus
– membrane-bound structure that houses genetic material of cell

• chromatin
– dense fibrous material within nucleus
– contains DNA
– condenses to form chromosomes during cell division

• nuclear envelope
– double membrane structure that delimits nucleus
– penetrated by nuclear pores

• pores allow materials to be transported into or out of nucleus

microbiology (42 decks)

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