Microbiology Exam 1 pt 2 Flashcards
Dry mount
Fixing bacteria to a slide:
*Heat
*Chemical
Staining:
*Helps to visualize cells
*Cells must be fixed to the plate to stain
Dark field Microscopy
A dark background with a light specimen
Often visualized using fluorecent stains
Good for visualizing specific cell parts
Phase Contrast
Mid tone between brightfield and darkfield
Often done woth a wet mount
Good for visualizing motility
Brightfield
Dark specimen on a light background
Most common
Requires a stain to visualize
Types of staining
Simple vs Differential Stains
Gram Staining
Acid Fast Stain
Stains Mycolic Acids
Will work for specimens that won’t gram
stain
Endospore Stain
Malachite Green for endospore stain
Safranin for rest of the cell
Negative Stain
Stains the background
Flagella Stain
Fluorescent
Gram Stain Procedure
- Heat fix cells to slide
- Stain w/ crystal violet
- Use a mordant (grams iodine)
- Wash cells with decolorizer (alcohol)
- Stain cells w/ Saffranin
Gram + = purple
Gram - = pink
Nutrition
Essential nutrients
Macro: CHNOPS and Mg2+, Fe2+, Ca2+,
K2+
Micro/Trace: Co, Cu, Mn, Zn, Mo, Ni
Growth
Binary fission- exponential
2n, n= number of generations
Budding
Multiple fission
Three Phases:
Growth after cell is “born”
Chromosome replication and partitioning
Cytokinesis
Bacterial growth curve
5 distinct phases
1. Lag phase
2. Exponential phase
3. Stationary Phase
4. Death phase
5. Long-term stationary phase
Generation time
For binary fission: Nt=No x 2n
Cultures and media
Cultures
Liquid or broth: best for singular type of
bacteria
Solid: best for different types of bacteria
Medias
Complex: nutrient-rich but poorly
defined
Synthetic: precisely defined
Enriched: complex media with blood
(fastidious)
Differential: differentiates between
different bacteria
Selective: selects for one bacteria to
survive over others, inhibits certain
bacterial growth
Isolating colonies
Dilution streaking: dragging a loop of bacteria across an agar plate
Spread plating: serial dilutions
Measurement of cell numbers
Counting chambers
Membrane filters
Pour plate
Optical density
Morphology of bacteria
Cocci:
Circular shape
Can be gram +/-
Can have parallel planes, perpendicular
planes, and random planes
Baccili:
Rod shape
Almost all are gram +
What makes up the bacterial cell w/ organelles
Thick outer envolope
Compact genome
Coordinated cell functions
No nucleus, nucleoid instead
Organelles:
Cytoplasm
Cell membrane
Cell wall
Nucleoid
Flagella (not all bacteria)
Ultracentrifugation
Allows you to look at the components of a cell
Cell membrane composed of
The structure that defines the cell
composed of lipid bilayer
proteins embedded
Fulidity
Hydrophillic polar head
Hydrophobic nonpolar tail
ether bonds are what allows archaea to
survive in extreme temps
Membrane Proteins functions
Provide structural support
Detect environmental signals (ex. toxins)
Secretion of things in/out of the cell
Transporting ions and energy storage
Transportation
Passive:
Moves with the gradient
High to low
No energy required
Ex. simple diffusion, osmosis, facilitated
diffusion
Active:
Requires energy (ATP)
Usually comes in the form of ATP
hydrolysis
Cell wall composed of
Most bacteria cell walls contain peptidoglycan.
A target for antiobiotics
Peptidoglycan contains:
N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
Peptidoglycan layers are bound together by a peptide
Gram +
Thick layer of peptidoglycan which is anchored by teichoic acid
Teichoic acid attaches to NAM of
tetrapeptide
Have capsules
protects cells from phagocytosis
Allows organisms to adhere to surface
colonize host
Have an S-layer
in almost all archaea and free-living
bacteria
consisting of a protein or glycoprotein
Gram - cell wall composed of
Thin layer of peptidoglycan
LPS (lipopolysaccharides)
O-polysaccharides
Outer Membrane
Inner membrane
Lipoproteins
Inclusions
Formed by an aggregate of Organic and Non-Organic Substances
ex. Granules, Crystals, globules
Microcompartments: can house specific
enzymes (ex. rubisco)
Gas vacuoles: important for microbe
buoyancy
Magnetosomes: Will orient the organism to
the Earth’s Magnetic Field
Ribosomes
Site of protein Synthesis:
70s Ribosome: Comprised of 30S and 50S (fit together to make 70s)
Nucleoid
Region that holds the cell’s Chromosome
Can be observed through microscopy
Some cells have multiple
Is help in tack by supercoiling DNA
