Exam I Flashcards
Symbionts that harm or live at the expense of their host:
parasitic organsims
Microbes frequently found within the bodies of healthy persons:
Commensal organisms
Commensal organisms may also be referred to as:
Normal microbiota
What makes up the vast majority of normal flora:
Bacteria
Colonization of ____ occurs rapidly after birth
Bacteria
Locations in which large amounts of bacteria reside:
- Skin (especially moist areas)
- Respiratory tract (nose & oropharynx)
- Digestive tract (Mouth & large intestine)
- Urinary tract (anterior parts of urethra)
- Genital system (vagina)
Location in which small amounts of bacteria reside:
Remainder of respiratory & digestive tracts
Locations in which no bacteria are present are considered:
sterile
Sterile locations in the body:
- Blood
- CSF
- Synovial fluid
- Deep tissues
Normal flora; found all over:
Resident organisms
Resides in an area for a limited time:
Transient organisms
Growth & multiplication of parasite on or within host:
Infection
Disease resulting from infection:
Infectious disease
Any parasitic organism that causes infectious disease by DIRECT interaction with host:
Primary (Frank) pathogen
Causes disease only under certain circumstances (such as after antibiotic tx)
Opportunistic pahtogen
Ability of a parasite to cause a disease:
Pathogenicity
Any component of a pathogenic microbe that is required for or that potentiates its ability to cause disease:
Virulence factor
Pathogenicity & virulence depend on:
The host
What are the steps in an infectious disease:
- Encounter
- Entry
- Spread
- Multiplication
- Damage
- Outcome
What are three types of encounters with a pathogen:
- Exogenous
- Endongenous
- Congenital
When a pathogen is externally derived such as a sneeze:
Exogenous encounter
When a pathogen is internally derived such as a change in immunity/health; already inside:
Endogenous encounter
When a pathogen is picked up during birth such as HIV; from mother to fetus:
Congenital encounter
What are two forms of entry of a pathogen:
- Ingress
- Penetration
Entry of pathogen via inhalation or ingestion:
Ingress
Entry of microbes through epithelia directly (via attachment & internalization)
Penetration
Insect bites, cuts & wounds, organ transplants, and blood transfusion are all examples of what type of pathogenic entry into the host:
Penetration
What are three components to the spread of a pathogen:
- Lateral propagation vs. dissemination
- Anatomical features
- Active participation by microbes
Spread of a pathogen to neighboring tissue:
lateral propagation
Spread of a pathogen to distance sites:
dissemination
What are two components to the multiplication of a pathogen when causing an infectious disease?
- Environmental factors
- Subversion of host defenses
Damage inflicted by an infectious can be caused by:
- Direct damage
- Immune response
What are the outcomes of an infectious disease:
- Microbe wins
- Host wins
- Learn to coexist
If an infection comes from our normal flora the source of infection is considered:
Endogenous
Overgrowth of particular bacteria in gingival crevices:
Periodontitis
When defenses are lowered and microaspirations of pneumococci occur:
Pneumococcal pnuemonia
Catheter-associated infections are typically a result of:
Staphylococci
What do the following have in common?
-Periodontitis
-Pneumococcal pneumonia
-Catheter-associated infections
All have endogenous source of infection- normal flora act opportunistically
What are the roles of normal flora:
- Immune stimulation
- Keeping out pathogens
- Assist in nutrition
- Source of carcinogens vs. detoxification of carcinogens
Normal oral flora include:
Bacteria
Fungi
Protozoa
Viruses
How many different species are estimated to be present in the oral cavity?
Over 500
What are the different oral habitats?
- Buccal mucosa
- Dorsal of tongue
- Tooth surfaces
- Crevicular epithelium
- Dental appliances
What are three issues microbial cells face?
- Nutritional fluxes
- Maintaining occupancy
- Resistance to damage
List all the factors modulating oral microbial growth:
- Anatomical features that create areas that are difficult to clean
- Saliva
- Gingival crevicular fluid
- Mircobial factors
- Local pH
- Redox potential
- Antimicrobial therapy
- Diet
- Iatrogenic factors
______ are an absolute requirement for all living organisms
Membranes
Describe the plasma membrane:
-Highly organized
-Asymmetric
-Flexible
-Dynamic
The lipid components of the plasma membrane form a:
Lipid bilayer
The polar ends of the lipids in the lipid bilayer are ____, while the non polar ends are _____
Polar –> Hydrophilic
Nonpolar –> Hydrophobic
Proteins that are loosely associated with the plasma membrane that can easily be removed:
Peripheral proteins
Proteins that are embedded within the plasma membrane that are NOT easily removed:
Integral
Bacterial version of cholesterol that provides rigidity:
Bacteriohopanetetrol
Functions of the plasma membrane include:
- Separation of cell from environment
- Selectively permeable barrier
- Location of crucial metabolic processes
- Detection & response to chemicals via receptors
Granules of organic and inorganic materials that are stockpiled by the cell for future use:
Inclusion bodies
Some inclusion bodies are enclosed by a:
Single-layered membrane
The single-layered membrane that encloses some inclusion bodies: (2)
- Vary in composition
- Some made of proteins others of lipids
Complex structures consisting of proteins and RNA:
ribosomes
Sites of protein synthesis
Ribsosomes
Compare the size of eukaryotic and prokaryotic ribosomes:
Prokaryotic ribosomes are smaller
Size of prokaryotic ribosome:
Size of eukaryotic ribosome:
70s
80S
Irregularly shaped region in bacteria in which the chromosome resides:
Nuceloid
Is the nucleoid membrane-bound?
No
In cells what do the nuceloid projections indicate?
Cells are actively growing; DNA being actively transcribed
Describe a prokaryotic chromosome:
Closed, circular double-stranded DNA molecule that is looped & coiled extensively
Proteins that help to fold a prokaryotic chromosome:
Nucleoid proteins
Describe some unusual circumstances of nucleoids:
- More than one chromosome
- Linear
- Membrane-delimited nucleoids
Small, circular DNA molecules that exist and replicated independently of the chromosome:
Plasmids
Plasmids are NOT required for:
Growth & reproduction
Plasmids may carry genes that confer ______ such as _____
Selective advantage; drug resistance
Rigid structure that lies just outside the plasma membrane:
Prokaryotic cell wall
List all the functions of the prokaryotic cell wall:
- Provides characteristic shape to cell
- Protects the cell from osmotic lysis
- May contribute to pathogenicity
- May protect cell from toxic substances
Bacteria are divided into two major groups based on:
Response to straining (reaction due to cell wall structure)
Gram positive cells stain _____
Gram negative cells stain ____
Purple
Pink
In a gram positive cell, the cell wall is composed of:
Primarily of peptidoglycan
Cells that contain large amounts of teichoic acids:
Gram positive cells
Polymers of glycerol or ribitol joined by phosphate groups:
Teichoic acid
Space between plasma membrane & cell wall:
Periplasmic space
Gram positive bacteria secrete:
Exoenzymes
In gram positive bacteria, exoenzymes serve as the _____ do in gram negative bacteria
Periplasmic enzymes
Cell wall consisting of a thin layer of peptidoglycan surrounded by an outer membrane:
Gram negative bacteria
The outer membrane in gram negative bacteria is composed of:
Lipids, lipoproteins, LPSs
NO teichoic acid present:
Gram negative bacteria
What type of bacteria are more permeable?
Gram negative
Space between plasma membrane & outer membrane in gram negative bacteria:
Periplasmic space
In gram negative bacteria, what is contained within the periplasm?
Periplasmic enzymes
What are the roles of periplasmic enzymes?
- Nutrient acquisition
- Electron transport
- Peptidoglycan synthesis
- Modification of toxic compounds
Describe the structure of peptidoglycan:
-Polysaccharide formed from peptidoglycan subunits
-two alternating sugars form backbone
What two alternating sugars form the backbone of peptidoglycan?
N-acetylglucosamine (NAG)
N-acetylmuramic acid (NAM)
Within the peptidoglycan structure, ____ have a direct link between peptide chains, while _____ contain a peptide interbridge (GLY) between side chains
Gram negative bacteria
Gram positive bacteria
What type of bacteria does this cell wall belong to?
Gram positive bacteria
What is under the thick peptidoglycan layer in a gram positive cell wall:
Single membrane bilayer
What type of bacteria does this cell wall belong to?
Gram negative bacteria
In a gram negative cell, there is a _____ structure with each being a bilayer
Double-membrane structure
Connect outer membrane to peptidoglycan in gram negative bacteria:
Braun’s lipoproteins
Sites of direct contact between plasma & outer membrane in gram negative bacteria:
Adhesion sites
Substance may move DIRECTLY into gram negative bacteria via:
Adhesion sites
Lipopolysaccharides are found in what type of bacteria?
Gram negative
What are the components of a lipopolysaccharide (LPS):
- Lipid A
- Core polysaccharide
- O side chain (O antigen)
Component of the LPS that inserts into the outer membrane structure for stabilization & can also act as an endotoxin:
Lipid A
The lipid A component of the LPS inserts into:
the outer membrane
Component of the LPS that contributes to the negative charge on the cell surface:
Core polysaccharide
What does the negative charge contributed by the core polysaccharide portion of LPS function to do?
Avoid/masks host defenses
What two components does the core polysaccharide portion of the LPS contains?
Keto-deoxoctogenic acid & heptose
Portion of the LPS that provides protection from host defenses:
O side chain (O antigen)
What component of the LPS is visible to our immune system?
O antigen
Which membrane is more permeable in a gram negative cell?
Outer membrane
Why is the outer membrane of a gram negative cell more permeable than the plasma membrane?
Due to presence of porin proteins & transporter proteins
Form channels in the outer membrane through which small molecules can pass:
Porin proteins
Layer outside of the cell wall that is well-organized, not easily removed from the cell & takes the shape of the underlying cell:
Capsule
Layer outside the cell wall that is similar to the capsule except diffuse, unorganized & easily removed:
Slime layer
Capsules & slime layers are both referred to as:
Glycocalyx
Network of polysaccharides extending from the cell surface:
Glycocalyx
What are the functions of the glycocalyx (4):
- Protection from viral infection or predation by bacteria
- Protection from chemicals in environment
- Motility of gliding bacteria
- Protection against osmotic stress
Short, thin, hairlike proteinaceous appendendages (1000/cell)
Fimbriae
What is the function of fimbriae:
Mediate attachment to cell surfaces
Similar to fimbriae except, longer, thicker & less numerous (1-10/cell)
Sex pilli
What are sex pilli required for?
Mating; transfer of genetic material
What is the function of flagella?
Motility
List the arrangements of flagella:
- Monotrichous
- Polar flagellum
- Amphitrichous
- Lophotrichous
- Peritrichous
One flagellum:
Monotrichous
Flagellum at end of cell:
Polar flagellum
One flagellum at each end of cell:
Amphitrichous
Cluster of flagellum at one or both ends of cell:
Lophotrichous
Flagellum spread over entire surface of cell:
Peritrichous
Describe the ultrastructure of the flagellum:
Filament, basal body, hook
Portion of flagellum that projects out of cell surface:
Filament
Portion of flagellum that is anchored with the plasma membrane or within both plasma & outer membrane:
Basal body
Portion of the flagellum that is a protein component that gives a bend to the structure:
Hook
Dormant form created when the bacterium encounters environmentally challenging conditions that make it difficult for the cell to keep growing:
Endospore
The bacterial endospore is resistant to numerous harsh environmental conditions including:
-heat
-radiation
-chemicals
-dessication
Overview of eukaryotic cells include:
- Membrane-delimited nuclei
- Membrane-bound organelles that perform specific functions
- More structurally complex than prokaryotic cell
- Generally larger than prokaryotic cell
Elements required in larger amounts:
Macroelements
List the macroelements required for microbial physiology that are cell components of carbs lipids, proteins & nucleic acids:
- Carbon
- Oxygen
- Nitrogen
- Hydrogen
- Sulfur
- Phosphorus
The macroelements required for microbial physiology make up components of:
- Carbohydrates
- Lipids
- Proteins
- Nucleic acids
List the macrolelements required for microbial physiology that exist as cations & play many roles, including cofactors of enzymes:
- Potassium
- Calcium
- Magnesium
- Iron
List the trace elements required for microbial physiology:
- Manganese
- Zinc
- Cobalt
- Molybdenum
- Nickel
- Copper
Trace elements are mainly needed as:
Cofactors of enzymes
Components required for ALL organisms survival:
- Source of energy
- Source of reducing equivalents (electron donors)
- Source of carbon
Organisms that utilize light as a source of energy:
Phototrophs
Organisms that oxidize organic or inorganic compounds as a source of energy:
Chemotrophs
Organisms need electron donors for:
- ETC (energy production)
- Redox reactions (energy production)
- Biosynthesis (in autotrophs from CO2)
Utilize INORGANIC molecules as a source of reducing agent:
Lithotrophs
Utilize ORGANIC molecules as a source of reducing agent:
Organotrophs
Utilize CO2 as the main/only source of carbon:
Autotrophs
Utilize reduced, preformed organic molecules (such as glucose) for source of carbon:
Heterotrophs
Due to the source of carbon utilized, most pathogenic bacteria are considered:
Heterotrophs
-Light energy source
-Inorganic electron donor
-CO2 carbon source
Photolithoautotrophy
-Light energy source
-Inorganic electron donor
-CO2 carbon source
Photolithotrophic autotrophy
-Light energy source
-Organic electron donor
-Organic carbon source
Photoorganotrophic heterotrophy
-Chemical energy source
-Inorganic electron donor
-CO2 carbon source
Chemolitotrophic autotrophy
-Chemical energy source
-Organic electron donor
-Organic carbon source
Chemoorganotrophic heterotrophy
(ALL PATHOGENS)
Other nutrient sources required for bacteria include:
-nitrogen source
-phosphate source
-sulfure source
-growth factors
List where bacteria may get their source of nitrogen from:
Amino acids, ammonia, or nitrate NO3-
A few bacteria may obtain nitrogen from N2 (atmospheric/gaseous nitrogen)
List where bacteria may get their source of phosphate from:
Inorganic phosphate (PO4^3-)
List where bacteria may get their source of sulfur from:
Sulfate (SO4^2-) or reduced sulfur (Cysteine)
List where bacteria may get their growth factors from:
Amino acids
Purines & pyrimidines
Vitamins (small organic molecules)
-Perform aerobic respiration only
-Final electron acceptor is oxygen (reduced to H2O)
Strict aerobes
-Perform anaerobic respiration
-Final electron acceptor is an inorganic molecule (such as nitrate or Fe3+)
Strict anaerobe
-Perform fermentation
-Final electron acceptor is an organic molecule (such as pyruvate reduced to lactase or acetyl-coA reduced to ethanol)
Strict anaerobe
-Can perform respiration & fermentation
-Most medically relevant bacteria
Faculative anaerobes
Final electron acceptor for strict aerobes:
oxygen (reduced to H2O)
Final electron acceptor is an inorganic molecule:
Strict anaerobe performing anaerobic respiration
Final electron acceptor is an organic molecule:
Strict anaerobe performing fermentation
Give & explain an example of a facultative anaerobe:
E. coli can survive on a Petri dish (aerobic) & can survive in the intestines (anaerobic)
The respiratory chain of E.Coli occurs in the ______; for use, it occurs in the ______
Membrane of cell; mitochondria
Unique to the oral cavity & requires a certain amount of CO2 in addition to oxygen:
Capnophilic
List the gram positive bacteria in the oral cavity:
- Streptococcus
- Peptostreptococcus
- Actinomyces
- Lactobacillus
List the shapes of the following gram positive oral bacteria:
- Streptococcus
- Peptostreptococcus
- Actinomyces
- Lactobacillus
- Cocci
- Cocci
- Rods
- Rods
List the oxygen requirements for the following gram positive oral bacteria:
- Streptococcus
- Peptostreptococcus
- Actinomyces
- Lactobacillus
- Facultative anaerobes
- Strict anaerobes
- Strict/facultative anaerobes
- Facultative anaerobes
List the gram negative bacteria found in the oral cavity:
- Veilonella
- Aggregatibacter
- Capnocytophaga
- Porphyromonas
- Prevotella
- Fusobacterium
- Spirochetes
List the shapes of the following gram negative oral bacteria:
- Veilonella
- Aggregatibacter
- Capnocytophaga
- Porphyromonas
- Prevotella
- Fusobacterium
- Spirochetes
- Cocci
2-6. Rods - Spirals
List the oxygen requirements for the following gram negative oral bacteria:
- Veilonella
- Aggregatibacter
- Capnocytophaga
- Porphyromonas
- Prevotella
- Fusobacterium
- Spirochetes
- Strict anaerobes
- Capnophilic
- Capnophilic
4-7. Strict anaerobes
-Move from higher concentration to lower concentration
-NO ENERGY requirements
Facilitated diffusion
What is facilitated diffusion uptake driven by?
Intracellular use of the compound
Compare the rate of facilitated diffusion vs. passive diffusion:
Facilitated diffusion is much fast =er
What happens to the rate of facilitated diffusion as the concentration gets smaller:
As concentration gets smaller, the rate gets smaller, however rate is more magnified at smaller concentrations
Carrier proteins embedded in the plasma membrane:
Permeases
An active transport mechanisms in which transported substances are chemically altered during the process:
Group translocation
Group translocation may also be called:
Phosphorylation-linked transport or Phosphotransferase system
An example of group translocation would be:
Glucose –> Glucose-6-phosphate
System that moves a phosphate group & covalently links it to a transporter molecule; very common within bacterial cells
Group translocation
Where does the phosphate bond come from in group translocation & what does this serve as?
Phosphoenolpyruvate (PEP); energy source
Some _____ & _____ are transported via group translocation:
Sugars & cariogenic bacteria
Energy use to drive the accumulation of substance, which remains unchanged by the transport process
Active transport
Form of active transport that uses proton notice force (proton gradient) by coupling to an energetically unfavorable transport event (concentration of substance against the gradient)
Ion-driven transport systems
Give an example of a molecule that would use ion-driven transport systems:
Amino acids
Coupling energetically favorable + unfavorable processes
Symport
Form of active transport that use membrane proteins that form a channel & drive substances through the channel using the energy from ATP hydrolyses:
Binding protein-dependent transport systems
Give an example of a molecule that would use binding protein-dependent transport systems:
Sugars & amino acids
In all active transport mechanisms, the transport processes use carrier that:
Can become saturated
Ferric iron is very ______ so ______ is difficult
Insoluble; uptake
Because ferric iron is insoluble & difficult to uptake, microorganisms use ____ to aid in the uptake
Siderophores
Describe the process of ferric iron uptake in microorganisms:
Siderophore complexes with ferric iron & the entire complex is then transported into the cell
E.Coli can grow on greater than 30 different _____ compounds, using each to obtain _____ , _____ & _____
Organic compounds; carbon, H+/Electrons, energy
Bacteria that can use several hundred compounds to obtain carbon, reducing agents & energy:
Pseudomonas
________ organisms have complex needs and can only grow in association with the human body or in complex culture medium (ex. Blood agar)
Nutritionally fastidious
Give an example of nutritionally fastidious bacteria:
Staphylococci & streptococci
Have to replicate within living cells, but unlike viruses, they can carry out metabolic processes:
Obligate intracellular parasites
Give an example of a bacteria that is an obligate intracellular parasite:
Chlamydia
Microbial growth in real world is considered:
Suboptimal
Different organisms have ______ growth rates
Variable
What is a factor that protects bacteria:
Stress responses
Bacteria can still cause damage to the host when not growing through:
Immunogenic processes & toxin production
Mechanisms of adaptation of bacteria function to:
- Maximize efficiency in using energy & resources
- Respond to changes
What are the results of regulation by microorganism:
- Pathways can be switched on or off
- Pathways can be turned up or down
How is control among microorganisms established?
- Enzyme activity
- Number of enzyme molecules
All enzymes have ______ for catalysis, but some enzymes also have _____ for regulation
Active sites; allosteric sites
_______ sites bind regulatory molecules
Allosteric sites
Describe the binding of a regulatory molecule to an allosteric site on an enzyme:
- Noncovalent
- Reversible
- Affects activity of enzyme
Positive effectors ____ activity; while negative effectors ____ activity of an enzyme:
Increase; decrease
In allosteric regulation:
Higher concentration of regulatory molecules =
More activity
In allosteric regulation, effectors act to:
- Change affinity of enzyme for substrate
- Change Vmax (rate of reaction)
Results in the prematures termination of transcription of mRNA:
Attenuation
In attenuation, the _____ becomes stalled in the _____ of the mRNA (upstream of the coding region on the enzyme)
Ribosome; attenuator region
During attenuation even though transcription is not complete, what can occur, & why?
Translation can begin, because transcription & translation occur simultaneously in bacteria
During attenuation, ______ are important for mRNA folding
Secondary structures (hairpin)
An example of a secondary structure used for mRNA folding during attenuation:
Hairpin
In attenuation, what happens when leucine is present?
When leucine is present, leucine-rich region allows ribosome to read & translate A & B regions causing formation of a C-D hairpin structure
In attenuation, when leucine is present and a C-D hairpin structure is formed, this causes:
The RNA polymerase to dissociate from the DNA, resulting in terminating transcription
In attenuation, when leucine is present and a C-D hairpin structure is formed, this causes the termination of transcription, ultimately:
Preventing the cell from making the enzyme to create more leucine
In attenuation, what happens when leucine is absent?
When leucine is absent, a high demand for leucine tRNA causes ribosome to stall, allowing for formation of B-C hairpin structure