Bacteriology Flashcards
eukaryotic cells characteristics
10-100 micron
- true nucleus and membrane bound organelles
- 80 s ribosomes in mitochondria
- flagella and cytoskeleton
- multiple linear chromosomes
- mitosis and meiosis
prokaryotic cells characterics
- 2-2 micron
- no nucleus has nucleoid area
- simple flagella
- 70s ribosomes
- single circular ribosomes
- binary fission replication
prion
only present in bacteria
bacterial shapes
cocci- spherical
strepo-long chain, diplo ( pairs), entero ( intestine)
bacilli- rod shaped
cocco ( egg shaped)
spiral bacteria ( corkscrew)
- vibrio ( comma)
- spirillum ( spiral, wavy)
- spirochaete ( old telephone, coiled)
different types of stains
simple- one color only, white background
differential- gram stain and acid fast
capsule- colors background and bacteria, shows capsule that exclude stain from around organism ( HALO effect)
gram stain
based on cell wall structure- amount of peptiologlycan ( mesh/lattice structure)
- useful for antibiotics and tissue damage
- rapid and allows us to see if there is bacteria
gram stain procedure
- fix specimen on slide and flood with methanol or pass slide through a flame
- Add primary stain- crystal violet ( gentian)
- Add mordant to keep stain stay in cells-iodine
- Add acetone-alcohol wash (decolorizer) to wash away purple brown color
differentiation step: + retain statin and is purple, - lose all stain and is colorless (leaky cell wall) - add safranin (counter stain) to allow visibility in microscope
+ doesn’t effect
- we can see it now!
gram negative
thin layer peptidoglycan -no teichoic acid - lipolysaccharide -outer membrane and periplasm ( space in inner cell wall) -less susceptible to penicillin pink/red
gram positive
remains purple
- thick layer peptidoglycan
- teichoic acid present allowing stick to surface charge
- no lipopolysaccharide
- no outer membrane or periplasm
- more susceptible to penicillin
Ziehl-Neelsen/acid fast stain
tests for TB
- have wax in cell wall
-carbon fuchsin is added to smear and heated to enhance penetration of dye
-colorization: acid-alcohol removes RED, methytone BLUE colors background
Ex: cryptosporidium- parasite that causes diarrhea
glycocalyx
capsule or slime layer ( outer most layer)
axial filament
internal flagella in spirochaetes
fimbriae and pill
hair-like appendages on gram - bacteria
sex pilus
transfer of genes ( DNA from cell to cell)- conjugation
peptidoglycan
lattice structure, provides structure for gram +
lipopolysaccharide
outer membrane in gram -
- lipid A: endotoxin ( inflammation)
- polysaccharide: O antigen ( typing)
teichoic and lipoteichoic acids
attach to peptidoglycan layer, projects outwards and cause cells to have negative charge, easier attachment to host cells and tissues
inclusions
reserve deposits of nutrients for bacteria
Endospores
genetic material in thick coat, no metabolic activity, resistant to heat and drying chemicals. Clostridium and bacillus produce endospores
metabolism
sum total of all chemical reactions within an organism.
- Catabolic: release energy
- Anabolic: produce store energy
physical factors for microbial growth
- temperature: pyschrophiles: cold loving
- thermophiles: heat loving
- hyperthermophiles: hot spring - pH
- 5 to 8 for human pathogens
- acidophiles down, alkalophile up - Osmotic pressure
- obligate halophiles is INCREASE salt
- falculative halophiles is TOLERATE salt
growth requirements for microbacteria
strict aerobe- needs O2 facultative anaerobe- both Strict anaerobe- minimal O2 Aerotolerant anaerobe- some O2 microaeroble- needs a little of both
bacterial growth curve
lag-infection
log- growth of bacteria
stationary-stops growth
death-dies!
biofilms
lives in communities like the plaque on our teeth, WBC can’t penetrate, antibiotics are ineffective
Agar
complex polysaccharide from algae for culture matrix, add animal blood
differential vs. selective media
differential- blood agar, hemolytic reactions ( breakdown of RBC that are mixed with agar) A-partial, B-total, G-none
selective- prevents species from growing and induce others to grow
