BACTERIAL STRUCTURE Flashcards
Acts as osmotic barrier
regulates transport of solute across membrane
Cell membrane
Cell membrane chemical composition
lipopolysaccharide (phospholipid bilayer)
Food reserves are called
Metachromatic granules
Main component of a cell wall
Murein layer/Peptidoglycan
metachromatic granules of Corynebacterium diphtheriae
Babes ernst bodies
metachromatic granules of Yersinia pestis
Bipolar bodies
metachromatic granules of Nocardia and actinomyces
Sulfur granules
Thicker cell wall
With teichoic acid
Impermeable to alcohol
Gram (+) Acid fast organisms
Thinner cell wall
endotoxin
Permeable to alcohol
with protein & phospholipids
Gram (-) Acid fast organisms
Chemical composition of Gram (+) Acid fast organisms
n-acetyl muramic acid & n-acetyl glucosamine
3 regions of LPS ( gram (-) )
- Lipid A
- Core polysaccharide
- Antigenic O
Slimy, gelatinous compound surrounding the cell wall
Prevents phagocytosis
Capsule
Chief determinant of virulence factor; delays digestion of bacteria
Capsule
Prevents phagocytosis
best demonstrated by negative staining
Capsule
Polysaccharide capsule:
H. influenza
K. pneumoniae
S. pneumoniae
B. anthracis (capsule)
D-glutamic acid
S. agalactiae (capsule)
Sialic acid
Shorter than flagella
Not present in all organisms
Extrachromosomal DNA carries antibiotic gene
Capsule
Short, hairlike structure that extend from cell membrane
into the external environment
Pili/Fimbriae
Chemical composition of Pili/Fimbriae
Pilin
responsible for attachment/adherence of microorganism to tissues; first step in establishing infection
Common pili
for coagulation, important in medical diagnosis
sex pili
Slender, whiplike structures which determines the motility of an organism; motility is best at 25C
Flagella
No flagellum
atrichous
One flagellum at one end
Monotrichous
Example monotrichous organisms
Vibrio and Pseudomonas
One flagellum on both ends
Amphitrichous
group of flagella on one or both ends
Lophotrichous
has flagella that surrounded the whole bacteria
Peritrichous
Chemical composition of flagella
flagellin
Gliding motility
capnocytophaga
Shooting star:
Vibrio cholerae
Corkscrew motility
Spirochetes
Tumbling motility
Listeria monocytogenes
Darting motility
Campylobacter
Keratin like coat
Resistant structures
Target of sterilization
Produced by Gram (+) organisms
Endospores/Spores
Chemical composition of endospores
Calcium dipicolinate
Excreted by living bacterial cells
Heat labile (60C)
Produced by gram (+)
Exotoxin
highly antigenic; highly toxic
Exotoxin
Examples of Exotoxins
- Enterotoxin
- Cytotoxin
- Neurotoxin
Liberated by cell walls when disintegrated
Heat stable (60C)
not antigenic; weakly toxic
produced by gram (-)
Endotoxin
Detects endotoxin in body fluids
Limulus Lysate test
Non-poisonous form of toxins
Toxoids
Ways of converting toxins to toxoids
- By aging
- By exposure to heat
- By exposure to 50% alcohol, formaldehyde, dilute acids
Generation time of T. pallidum
33 hrs
Generation time of M. tuberculosis
18 hrs/20-22 hrs
Generation time of S. aureus
30 minutes
Generation time of E. coli
20 minutes
Phase of Rejuvenescence
No cell division
# of cells at the beginning equal to the number of cells at the end of lag phase
Lag Phase
Bacterial division at constant rate
Rapid exponential growth
Population doubles
Log Phase
Decrease in bacterial growth may last for 1-2 days
New cells equal the number of dying cells
Stationary Phase
In stationary phase, dead debris starting to accumulate due to:
Accumulation of toxin
Lack of food
Development of unfavorable pH
Complete cessation of multiplication
Death Phase
metachromatic granules of Mycobacterium group
Much granules
