Price Lectures Exam 1 Flashcards
Infectious vs. contagious
Infectious–disease caused by living organism
Contagious–spreads from host to host
All contagious diseases are infectious, but not vice versa
Disease carrier
organism that appears healthy but is shedding the virus
What is virulence?
ability of organism to cause disease
what is LD50? how does it relate to virulence?
LD50 is number of organisms needed to kill 50% of population;
a LOWER LD50= MORE virulent
What does it mean if an organism is a facultative anaerobe?
is fine with or without oxygen
The cell envelope consists of all layers outside the _____
cytoplasm
What is the outer most layer of the envelope?
capsule
What is the significance of the capsule? (2)
1) antiphagocytic (new infections)
2) important for serotyping
When using the capsule for serotyping, what is the identifying structure?
K antigen
Glycocalyx vs. slime layer? Function(s) of each?
Glycocalyx–> TIGHTLY bound onto capsule; for adherence
Slime layer–>LOOSELY bound; adherence and antiphagocytic
Are flagella unique to gram positive or negative?
No; can be found or absent in either
Important antigen of flagella?
H antigen
What is phase variation?
Bacteria can change protein sequence of flagella to “hide” from antibodies made against original sequence
What is Conjugation? What type of gene transfer is it?
exchange of genetic information using sex pilus;
horizontal gene transfer
In conjugation, which cell produces the sex pilus?
the donor cell
Which bacterial family lacks peptidoglycan?
Mycoplasma
What two molecules alternate to make up the peptidoglycan backbone?
NAG and NAM
The composition of which component of the peptidoglycan varies between spp?
tetrapeptide chain
What are permeases?
proteins that regulates movement in and out of the cell (located in cytoplasmic membrane)
Location of hydrolytic enzyme secretion:
1) Gram +
2) Gram -
1) into external medium
2) periplasmic space
Detergents, polymyxins, and ionophores all target what bacterial structure?
cytoplasmic membrane
2 reasons plasmids are relevant?
1) can encode antibiotic resistance
2) can encode virulence factors (i.e. toxins)
tecichoic acids and endospores are unique to?
Gram positive bacteria
3 functions of techoic acids?
1) bind Mg2+
2) autolysis
3) protection from antimicrobial peptides
Name 4 structures unique to gram negative bacteria?
1) Lipoprotein
2) Outer membrane
3) Lipopolysaccharide (LPS)
4) periplasmic space
Function of lipoprotein?
anchors outer membrane to peptidoglycan
Function of outer membrane?
protects cell from host environment
Name the 3 major abundance proteins found in outer membrane
1) Matrix porins
2) specific porins
3) Non-porin OM proteins
Name the 3 portions of LPS
1) Lipid A
2) Core polysaccharide
3) O-specific polysaccharide (O antigen)
This portion of LPS is the “endotoxin”
Lipid A
Which portion of LPS shows the most variation between spp and confer antigenic specificity?
O-antigen
Bacteriostatic vs. bacteriocidal
bacteriostatic–reversibly alters growth
bacteriocidal–irreversibly inhibits growth
What are the 4 mechanisms of antibiotics
inhibit cell wall synthesis
inhibit membrane function
inhibit protein synthesis
inhibit nucleic acid synthesis
Penicillins, cephalosporins, bacitracin, cycloserine, vancomycin, and carbpenems mode of action?
inhibit cell wall synthesis
Polymyxins, amphotericin B, ketoconazole, ionophores mode of action?
inhibit cell membrane function
Which drug is anti-fungal?
Amphotericin B
Aminoglycosides, tetracyclines, chloramphenicol, erythromycin, and clindamycin mode of action?
inhibit protein syntesis
Which drugs target the SMALL ribosome subunit?
aminoglycosides and tetracyclines
which drugs target the LARGE ribosome subunit?
chloramphenicol, erythromycin, and clindamycin
Fluoroquinolones, rifampin, sulfonomides, trimethoprim, and metronidazole mode of action?
inhibit nucleic acid synthesis
