Characteristics Of Microorganisms Flashcards
Commensal organism
- specific locations of human body
- prevent disease
Pathogen
- cause damage to human tissue
- infection and disease (result)
Microorganism
- cannot be seen w/ unaided eye
- often unicellular
Prokaryotic cell
- lack true membrane enclosed nucleus
- genetic material in a nucleoid (single circular chromosome)
Eukaryotic cell
- true membrane bound nucleus (several chromosomes)
- fungi and animals
Four major classes of microorganisms
- Protozoa
- Fungi
- Bacteria
- Viruses
Cytoplasmic membrane
- separates cytoplasm from cell wall
- LIPOPROTEIN
Function: Cytoplasmic Membrane
- site of electron transport system
- regulates osmotic pressure in cell (diffusion or active transport, waste out of cell)
- repsonsible for detection of environmental cues for chemotaxis
Cell wall
-found immediately outside of cell membrane
Aka murein layer or peptidogylcan layer
Function: cell wall
- gives bacteria it’s shape
- murein layer has gel substance help secure nutrients from environment
- enzymes degrade macromolecules and detox substances enter through outer membrane
Gram Positive
- thicker layer of peptidoglycan
- cw contains teichoic acid and lipoteichoic acid
Gram Negative
- cw w/ 2 layers, innermost = thin peptidoglycan, outer = protein, lipopolysaccharide and phospholipid
- periplasmic space (between internal surface of outer membrane and external surface of cellular membrane)
100x
Oil immersion
stained slides
40x
Wet mounts w/ coverslip
10x
Focus slide and count for cells
Gram stain
- Crystal violet (primary stain)
- Iodine (mordant)
- Acetone-Alcohol (decolorizer)
- Safranin (secondary stain)
Lag phase
Cells adjust to environment
Log phase
Exponential growth
*testing done here
Stationary phase
No increase in growth
Death
Cessation of growth
Media - forms?
- solid
- semi solid
- liquid
Simple media
- basic media
- non fastidious
Enriched media
Basic media + extra nutrients
Differential media
Basic media + differentiating substance (pH + sugar)
Selective media
Basic media + selective substances (increased salt content)
Enrichment media
Basic LIQUID media + additional substance specific for one organism
Media QC
- sterile
- stable
- reasonable shelf life
- clear and/or proper colour, consistency, depth, no hemolysis
Strict aerobes
Cannot grow in absence of O2
Facultative anaerobes
can grow aerobically or ANO2
Capnophilic
need increased CO2 (candle jar or incubator): 5-10 % CO2
Microaerophilic
need low levels of O2 (jar with pack)
Strict anaerobes
cannot grow in the presence of O2 (jar with pack=different pack!)
Media examination
- relative size
- pigmentation
- hemolytic reaction
- texture
- opacity
Alpha hem.
Green
Beta hem.
Clear
Gamma hem.
No change
Biochemical tests
- manual (individual tubes, manual interpretation
- API
- automated (Vitek, AST)
Serological tests
Confirmatory, or epidemiology purpose
Maldi-tof
Clinical labs
Results in minutes
Organism can be dead
Minimal cost