01 - Generalities Flashcards
non-SI unit for sedimentation rate; how fast is 1 unit?
svedberg unit = 10^-13 s (100 fs)
content of bacterial cell wall
peptidoglycan
content of fungal cell wall
chitin
The only bacteria with sterols in their membranes
Mycoplasma
jumping genes
transposons
What are prions?
naked proteins, same sequence as certain normal human cell surface proteins but have folded differently
vacuolated neurons with loss of function and the lack of an immune response or inflammation
spongiform encephalopathies
etiology and manifestation of Creutzfeldt-Jakob disease
Infection -> dementia
etiology and manifestation of Kuru disease
Cannibalism -> cerebellar disorders
another name for mad cow disease
bovine spongiform encephalopathy
how to disinfect tools from prions?
5% hypochlorite solution or 1.0 M sodium hydroxide or autoclaved at 15 psi for 1 hour
three shapes of bacteria and their descriptions
- cocci - spheres
- bacilli - rods
- spirochetes - spirals
arrangement of cocci and their descriptions:
- diplococci - pairs
- streptococci - chains
- staphylococci - clusters
All bacteria have a cell wall composed of peptidoglycan except:
Mycoplasma (have sterols in their cell membranes)
what enzyme cross-links the peptidoglycan?
transpeptidase
Units of the sugar backbone in peptidoglycan?
NAM and NAG
reason for resistance of MRSA?
alteration of the penicillin-binding protein
This drug targets the ala-ala residues of the peptidoglycan
Vancomycin
These bacterial cell wall proteins facilitate the passage of small, hydrophilic molecules into the cell
Porin proteins
Lysozymes are enzymes that kill bacteria by cleaving which part of the cell wall?
Beta 1->4 glycosidic bond betweeen NAG and NAM (in peptidoglycan)
Gram (+) vs Gram (-):
Peptidoglycan is thicker in
Gram (+)
Gram (+) vs Gram (-):
techoic acids are present in
Gram (+)
Gram (+) vs Gram (-):
lipopolysaccharide is present in
Gram (-):
another name for lipopolysaccharide:
endotoxin
Gram (+) vs Gram (-): periplasmic space
Gram (-):
What comprises an endotoxin?
lipid A and O antigen
Which Gram (+) bacteria have an endotoxin?
None, except for Listeria monocytogenes
steps in gram staining
- crystal Violet
- Iodine
- Acetone
- Safranin
VIAS
Enumerate:
Bacteria that cannot be seen in gram staining; why can’t we do gram staining; alternative approaches to detection
- Mycobacteriae - too much lipid in cell wall so dye cannot penetrate - acid fast staining
- Spirochetes - too thin to see - darkfield microscopy
- Mycoplasma - no cell wall - do serologic studies
- chlamydiae - intracellular and very small - giemsa stain
- rickettsiae - intracellular and very small - giemsa stain
- Legionella - poor uptake of red counterstain - silver stain
Oldest acid-fast staining method, which requires heating the specimen during the procedure.
Ziehl-Neelsen procedure
Which component of the gram (-) cell wall reduces its susceptibility to lysozymes?
outer membrane
Ribosomes of prokaryotes:
30S + 50S = 70S
Ribosomes of eukaryotes:
40S + 60S = 80S
invagination of the plasma membrane
mesosome
space between the plasma membrane and the outer membrane
periplasmic space
what is the function of the mesosome?
participates in cell division and secretion
what is the function of the periplasmic space?
contains many hydrolytic enzymes e.g. Beta-lactamases
This component protects the bacteria against phagocytosis
capsule
this component mediates adherence to surface and is responsible for the formation of biofilms
glycocalyx
These components are resistant to heat and chemicals
spores
Extrachromosomal, double-stranded, circular DNA capable of replicating independent of the bacterial chromosome
plasmid
site of nutrients in the cytoplasm
granule
What bacteria form spores?
Gram-positive rods, especially Bacillus and Clostridium, which are also exotoxin-forming
This bacteria has a protein capsule instead of a polysaccharide capsule:
What is it made of?
Bacillus anthracis
- polypeptide of D-glutamate
Term for fusion of plasmids with the bacterial chromosome:
episomes
Function of the plasmid
for antibiotic resistance and formation of new toxins
toxic proteins produced by certain bacteria that are lethal for other bacteria
bacteriocins
Process of killing all microbial forms, plus spores
sterilization
Process of applying chemicals on inanimate objects to kill some bacteria
disinfection
Process of killing bacteria present in living tissues
antisepsis
Physical removal of microorganisms
De-germing
Process of lowering the bacterial count
Sanitization
Chloramphenicol is bacteriostatic except for the following microorganisms: (4)
- Neisseria meninigitides
- Bacteroides fragilis
- Streptococcus pneumoniae
- Haemophilus influenza
No Boyfriend Since Highschool
Why are alcohol-based sanitizers ineffective against Clostridium?
because it can form spores
Enumerate the 4 phases of bacterial growth, and expain
- Lag phase
- log phase (exponential phase)
- stationary phase
- death phase (decline phase)
Phenomenon of a continued antibiotic effect despite its total elimination from the body
Post-antibiotic effect
substrate and product of superoxide dismutase:
- superoxide
- hydrogen peroxide and oxygen
substrate and product of catalase:
- hydrogen peroxide
- water and oxygen
substrate and product of peroxidase:
- hydrogen peroxide
- water
Completely dependent on oxygen for ATP-generation
obligate aerobes
use fermentation but can tolerate low amounts of oxygen due to presence of SOD
microaerophiles
utilize oxygen if present, but can use fermentation in its absence
facultative anaerobe
exclusively anaerobic but insensitive to the presence of oxygen
aerotolerant anaerobe
cannot grow in the presence of oxygen
obligate anaerobes
What enzymes do obligate anaerobes lack?
SOD, peroxidase, and catalase
examples of aerotolerant anaerobes
propionibacterium, lactobacillus
examples of obligate anaerobes
Actinomyces, Bacteroides, Clostridium
examples of obligate aerobes
Nocardia Neisseria Pseudomonas Mycobacteria Bordetella/Brucella/Bacillus cereus Legionella
Nosy and Nagging Pests Must Breathe Breathe Breathe Lots (of oxygen)
DNA transferred from one bacterium to another
Conjugation
DNA transferred by a virus from one cell to another
Transduction
Purified DNA taken up by a cell
Transformation
Normal flora of the skin
Staphylococcus epidermidis
Normal flora of the nose
Staphylococcus aureus
Normal flora of the mouth
viridans Streptococci
Normal flora of dental plaques
Streptococcus mutans
Normal flora of the colon
Bacteroides, E. coli
Normal flora of the vagina
Lactobacillus vaginalis, E. coli, Streptococcus agalactiae