microorganisms and the human body Flashcards
(83 cards)
1
Q
Microorganisms and the human body
A
bacteria, viruses, fungi, protozoa= microbiome
bacteria is vast majority
helminths (worms)
2
Q
Parasitic organisms
A
Parasitic organisms
Symbionts that harm or live at the expense of their host
3
Q
Commensal organisms
A
Normal microbiota - microbes frequently found on or within
the bodies of healthy persons
4
Q
Infection
A
–growth and multiplication of parasite on or within host
5
Q
Infectious disease
A
–disease resulting from infection
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
7
Q
Pathogenicity
A
Pathogenicity
–ability of parasite to cause disease
8
Q
Virulence factor
A
- any component of a pathogenic microbe that is required for
or that potentiates its ability to cause disease
9
Q
Steps in an infectious disease
A
encounter entry spread multiplication damage outcome
10
Q
ways encounter of infectious diseases
A
Exogenous, Endogenous, or Congenital
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
12
Q
spread of infection
A
lateral propagation (localized) versus dissemination (systemic infection)
anatomical factors
active participation by microbes with motility
13
Q
Multiplication of pathogen
A
environmental factors (e.g. temperature) can stimulate division subversion of host defenses
14
Q
damage from infection
A
direct damage from pathogen or from immune response
15
Q
infection outcomes
A
microbe wins, host wins, or they learn to coexist
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
17
Q
The Human Microbiome
A
the collection of all the microorganisms living in association with the human body
eukaryotes, archaea, bacteria and viruses
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
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
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
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)
22
Q
Other body locations have small numbers of bacteria
A
Remainder of respiratory and digestive tracts
23
Q
Some body locations are sterile.
A
blood, cerebrospinal fluid, synovial fluid, deep tissues
24
Q
Transient vs. resident organisms
A
transient- somtimes present
resident- always present
25
pathogenicity and virulence also depend on?
Pathogenicity/virulence also depends on the host
| Definition of pathogen not so certain
26
Examples where normal flora are source of infection:
periodontitis - overgrowth of particular bacteria in gingival crevices
pneumonia - defenses lowered and microaspirations of pneumococci.
catheter-associated infections - staphylococci
27
Oral flora includes
```
bacteria (and archeae)
fungi
protozoa (eukaryotes)
viruses
~700 different species of bacteria are estimated to
be present in the oral cavity
```
28
Oral habitats
```
buccal mucosa
dorsum of tongue
tooth surfaces
crevicular epithelium
dental appliances
```
29
Issues for microbial cells
Nutritional fluxes
Maintaining occupancy
Resistance to damage
30
Factors modulating oral microbial growth
```
anatomical features that create areas that are difficult to clean
saliva
GCF
microbial factors
pH
redox potential
antimicrobial therapy
diet
iatrogenic factors
```
31
Factors modulating oral microbial growth- anatomical features that create areas that aredifficult to clean
shape and topography of teeth e.g. fissures
malalignment of teeth
poor quality of restorations (e.g. fillings and bridges)
non-keratinized sulcular epithelium
32
Factors modulating oral microbial growth-saliva
components?
functions?
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
33
Factors modulating oral microbial growth-
| gingival crevicular fluid
```
flushing microbes out of crevice
source of nutrients for microbes
maintains pH
specific and non-specific defense factors
phagocytosis- neutrophils main phagocyte
```
34
Factors modulating oral microbial growth
| microbial factors
```
competition for adhesion receptors
toxin production
metabolic end products
negative vs. positive effects
congregation
```
35
Factors modulating oral microbial growth-local pH, how can it vary
will vary with diet as a result of bacterial metabolism
36
3 domains of life
eukaryotes, bacteria and arachea
37
Prokaryotic Cell Membrane
required?
encompasses?
possible internal membranes?
* membranes are an absolute requirement for all living organisms
* plasma membrane encompasses the cytoplasm
* some prokaryotes also have internal membrane systems
38
```
The Plasma Membrane
contains?
orgainzed?
symmetry?
flex/dynamic?
```
• contains lipids and proteins
– lipids usually form a bilayer
– proteins are embedded in or associated with lipids
• highly organized, asymmetric, flexible, and dynamic
39
The asymmetry of most
| membrane lipids
```
• polar ends
– interact with water
– hydrophilic
• nonpolar ends
– insoluble in water
– hydrophobic
```
40
other mem lipids
euk-cholesterol
| bac- hopanoid
41
Membrane proteins
peripheral proteins
– loosely associated with the membrane and
easily removed
• integral proteins
– embedded within the membrane and not easily
removed
42
Functions of the plasma
| membrane
• 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
Inclusion Bodies, membrane?
• 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
Ribosomes
```
• complex structures consisting of protein and RNA
• sites of protein synthesis
• smaller than eucaryotic ribosomes
– prokaryotic ribosomes Þ 70S
– eukaryotic ribosomes Þ 80S
```
45
The Nucleoid
• irregularly shapedregion
• location of chromosome (1, circular shaped)
– usually 1/cell
• not membranembound
46
nucleoid in actively growing cells
```
In actively
growing cells,
the nucleoid
has projections;
these probably
contain DNA
being actively
transcribed
```
47
The prokaryotic chromosome
| proteins with it?
```
• a closed circular, double-stranded DNA
molecule
• looped and coiled extensively
• nucleoid proteins probably aid in folding
– nucleoid proteins differ from histone
```
48
Unusual nucleoids
```
• some prokaryotes have > 1 chromosome
• some prokaryotes have chromosomes
composed of linear double-stranded DNA
• a few genera have membrane-delimited
nucleoids
```
49
Plasmids
relation to chromo?
required?
may carry?
• 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
The Prokaryotic Cell Wall
• rigid structure that lies just outside the plasma membrane
51
Functions of cell wall
* shape
* protects from osmotic lysis
* contribute to pathogenicity
* protect cell from toxic substances
52
Cell walls of Bacteria classes
| staining colors?
• 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
gram positive cell wall
54
gram negative cell wall
55
Periplasmic space
```
• 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
Periplasmic enzymes
found in what bacteria class?
functions?
```
• found in periplasm of gram-negative bacteria
• some of their functions
– nutrient acquisition
– electron transport
– peptidoglycan synthesis
– modification of toxic compounds
```
57
Exoenzymes
• secreted by gram-positive bacteria
• perform many of the same functions that
periplasmic enzymes do for gram-negative
bacteria
58
Peptidoglycan Structure
* 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
gram-negative vs gram-positive peptidoglycan linkages
gram -: D-ALA to DAP to form cross links
Gram +: peptide interbridge with Gly
both form the meshwork of peptidoglycan
60
Gram-Positive Cell Walls
| •additional content?
* composed primarily of peptidoglycan
| * also contain large amounts of teichoic acids, lipotechoic acid may anchor the peptidoglycan to the plasma membrane
61
teichoic acids composition
• polymers of glycerol
or ribitol joined by
phosphate groups
62
Gram-Negative Cell Walls
* 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
Important connections of gram - walls
• 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
Lipopolysaccharides (LPSs) components
• consist of three parts
– lipid A
– core polysaccharide
– O side chain (O antigen)
65
Importance of LPS
* 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
Other characteristics of outer membrane
• 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
Components External to Cell Wall
Capsules, Slime Layers, and SLayers
68
Types of material lying outside the cell wall
– 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
• glycocalyx
– 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
functions of layers external to the cell wall
* 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
Pili and Fimbriae
size compared
functions?
made of?
```
• 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
Flagella and Motility
required for motility
73
Patterns of flagellum arrangement
* 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
Flagellar Ultrastructure
```
3 parts
– filament
– basal body= anchor
– hook= bends structure for motion
DIFFERENT IN GRAM +/-
```
75
The Bacterial Endospore, resistant to?
```
• formed by some bacteria
• dormant
• resistant to numerous environmental
conditions
– heat
– radiation
– chemicals
– desiccation
```
76
An Overview of Eukaryotic Cell Structure
```
• membrane-delimited nuclei
• membrane-bound organelles that
perform specific functions
• more structurally complex than
prokaryotic cell
• generally larger than prokaryotic
cel
```
77
The Endoplasmic Reticulum
| what can be made here?
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
The Golgi Apparatus
• 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
Lysosomes
– membrane-bound vesicles
| – contain hydrolytic enzymes needed for digestion of macromolecules
80
• endocytosis
– 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
Mitochondria is the site of?
Mitochondria
• site of tricarboxylic acid cycle activity
• site where ATP is generated by electron transport and oxidative phosphorylation
82
Mitochondrial structure/ contents of different areas
• 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
The Nucleus, contents/components?
• 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
