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Microbiology
Terms and basics
46
Science
Graduate
05/08/2008

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Cards

Term
The unique presence of ______________ in fungal cell membranes is the most important target for antifungal drugs
Definition
Ergosterol
Term
What does amphotericin B and azole drugs do?
Definition
These drugs inhibit ergosterol synthesis
Term
What is a common target for antimicrobial drugs?
Definition

Peptidoglycan in the cell wall

70S ribosomes 

Term
What is the difference between Procaryotic and Eucaryotic microorganisms?
Definition

Procaryotes have 70S ribosomes and no defined nuclear membrane

 

Eurocaryotes have 80S ribosoomes and a defined nuclear membrnae

Term
Plasmids
Definition
Optional portion of bacterial genome.
 
Extrachromosomal dsDNA (usually circular).
Transferable between bacterias.
May contain gene encoded for antibiotic resistance or bacterial toxins
 
**Can replicate much more quickly than an entire genome.
Term
The bacterial chromosome is considered ___________ because of the rapid replication process.
Definition

Mirahaploid.

 

Technically haploid. 

Term

What is the difference between lytic and lysogenic? 

Definition
Lytic. The virus infects the cell, makes copies, and LYSES the cell for reinfection.
 
Lysogenic.The virus infects the cell, integrates itself into host DNA, and GENerates its chromosomal products (eg. exotoxins) 
Term
Bacteriophages
Definition
Viruses that specifically infect bacteria.
Term
What is the function of the cytoplasmic membrane in bacterial cells?
Definition
-selective protective barrier
-site of ATP production (no mitochondria)
-site of synthesis of cell wall precursors (eg. PG) 
Term
What is the composition of peptidoglycan?
Definition
-peptides and sugars
-NAM (N-acetyl muramic acid)
-NAG (N-acetyl glucosamine)
 
NAM and NAG crosslink to form chains, which are linked to form layers of the peptidoglycan network.
 
Term
What is the function of peptidoglycan?
Definition
Provides shape and rigidity to the cell.
Term
Transpeptidase
Definition

Forms the crosslinkage between NAM-NAG.

 

Cyclosporins inhibits transpeptidase. 

Term
Describe the cell wall structure of Gram Negative bacteria.
Definition
Gram stain:RED
 
THIN peptidoglycan layer
 
Outermembrane present with LPS (lipopolysaccharide).
Term
Describe the cell wall structureof Gram Positive bacteria.
Definition
Gram stain: PURPLE (purple = positive)
 
THICK peptidoglycan layer
 
No outermembrane. 
Term
O-antigen
Definition

Outer repeating polysaccharide located as part of the LPS of the outer membrane in GN bacteria.

 

Used for serological purposes to identify bacteria. 

Term
Endotoxin
Definition

A phospholipid known as lipid A, is part of the outer membrane of GN bacteria.

 

Can cause fever, HOTN, and septic shock

Term
What is the difference between endotoxin and exotoxin?
Definition
Endotoxin. Heat stable and bound to cell; only present in G- bacteria
 
Exotosin.Heat unstable and secreted by cell; may be present in G- or G+ bacteria
Term
Toxoids
Definition
Inactivated exotoxins used in vaccines
 
Eg. tetanus shot 

Term
Flagella
Definition

Composed of flagelin.

 

Used for bacterial motility. 

Term
Chemotaxis
Definition
Baterial sense of chemical gradients that motivates them to move toward nutrient rich environments.
Term
Fimbriae or Pili
Definition

Composed of firbilin or pilin.

 

Used for adherence, bacterial conjugation, and antiphagocytosis. 

Term
Endospore
Definition
-formed in response to poor conditions (low nutrients)
 
-formed inside vegetative bacterial cell
 
-most resistant life form to drying, heat, chemicals
 
Spore forming genuses: Bacillus, Clostridium 
Term
Aerobic
Definition
Only grows in the presence of oxygen.
Term
Anaerobic
Definition
Only grows in the absence of oxygen.
Term
Facultatve
Definition
can grow in the presence or absence of oxygen
Term
Capnophilic
Definition

Grows in the presence of little oxygen.

 

Candle jar. 

Term
Normal Flora
Definition
An ever present dynamic population of microorganisms that inhabits most of our epithelial/mucosal surfaces
Term
symbiosis
Definition
Host and microbe benefits
Term
Commensalism
Definition
beneficial to one, neither harmful or beneficial to the other
Term
Parasitism
Definition
beneficial to one, harmful to the other
Term
Name three benefits of normal flora.
Definition
1. synthesizes and excretes vitamins that can't be made by man
 
2. prevents colonization of pathogens by competing for attachment sites and/or essential nutrients
 
3. production of substances that eitehr inhibit or kill other indigenous non-specific bacteria
 
4. keeps the immune system antigenically primed for action 
Term
Pathogen
Definition
any disease producing microorganism
Term
Koch's postulate
Definition

Isolate suspected pathogen

 

Demonstrate absence in other healthy organisms

 

Induce suspected pathogen into healthy and produce disease

 

re-isolate suspected pathogen from newly infected subject for confirmation

Term
Exogenous pathogens
Definition
pathogens acquired from the environment or from other organisms
Term
Endogenous organisms
Definition
pathogens that are pathogenic microbes and are a part of our normal microflora
Term
Reservoir
Definition
The place where you would normally find a particular pathogen
Term
Vector
Definition
The thing that transmits the disease
Term
List four modes of transmission of exogenous bacteria
Definition
Congenital
Direct contact
Aerosol
Ingestion
Trauma
IV transfusion/percutaneous
Sexual 
Term
Opportunistic pathogen
Definition
microorganisms that are capable of producing disease given the oppoortunity
Term
How can bacterial endocarditis happen?
Definition
Trauma of the mouth.
 
Streptococcus sanguis is part of our normal tooth flora.
 
In an open wound of the mouth, it can enter the blood stream and attach itself to the heart walls, causing endocarditis. 
Term
How can pseudomembranous colitis happen?
Definition
Given a broad spectrum antibiotic.
 
Clostridium difficle is a normal flora of the colon.
 
Wiping out other normal flora, C. difficle can overgrow in colon and cause diarrhea with yellow-white plaques on the colon mucosa.
Term
Natural Active Immunity
Definition

Exposure to a disease, get sick, and successfully respond without a vaccine.

 

Memory T cells will allow immunity for next exposure. 

Term
Natural passive immunity
Definition
Can occur trans-placenta or through breast milk.
Term
Active artifical immunity
Definition
Synthetic vaccinations.
Term
Artificial Passive immunity
Definition
Injection of antibodies made from another person
Term
What is the advantage/disadvantage of natural and artifical immunization?
Definition
Natural. slow, but longer lasting
 
Artificial. fast, but shorting acting
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