Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
85 Cards in this Set
- Front
- Back
|
What kind of microscope is commonly used for bicrobiology lab?
|
A Compound Light Microscope
|
|
|
Know how to label parts of a microscope and be familiar with their function
|
ocular lens, objective lens, specimen area, condenser lens, diaphragm, light, eyepiece, stage, substage condensor, light source, focusing knob
|
|
|
What are the three things we can control or change with a microscope?
|
Magnification, Contrast, Resolution
|
|
|
Know how to calculate magnification power
|
Objective (10x-100x) x Ocular lens (10x always)
|
|
|
What is the magnification if you are using the 20x objective lens
|
200x its actual size
|
|
|
Resolution
|
being able to discern things that are really close together as distinct speciments
|
|
|
What is the highest possible resolution and what does that mean?
|
0.2 nanometers, that means that two features clsoer together than that are not resolvable as distince and separate
|
|
|
What is the equation for resolution
|
d (resolving limit) = 0.5 lammda (wavelength) / NA (numerical aperture
|
|
|
If you want a better resolving limit do you want a shorter/longer wavelength and a smaller/larger NA
|
shorter wavelength, larger NA
|
|
|
Which is the better resolution: 0.625 nanometers or 0.200 nanometers?
|
0.2 nanometers
|
|
|
If 2 microscopes are identical in every way except one using a bulb with more red light (#1) and one uses a bulb with more blue light (#2), which will give the better resolution?
|
red-600 nm wavelength and blue is -400 nm wavelength, so blue light because it has the shorter wavelength (#2)
|
|
|
Why do we care about contrast?
|
Most bacteria cells are difficutl to see due to lack of contrast since they are mainly water (over 90%), so they are very translucent and scatter light
|
|
|
What are ways to increase magnification?
|
Stronger microscopes ie. the electron microscope---Only Dead organisms can be viewed, expensive, training required, only view a digital image. Need to see viruses
|
|
|
How can we increase contrast?
|
using microscopes like modified light microscopes: dark field, phase contrast AND staining
|
|
|
What is special about modified light microscopes?
|
they increase contrast, and you can use live specimens. Better than staining--kills bacteria
|
|
|
What is the downside and upside to staining?
|
kills specimen but very cheap
|
|
|
Describe Gram Staining:
|
heat fixed, crystal violet, iodine solution, decolorized with ethanol, counter stain with safranin. + is dark purple and - is pink. Used for differentiation and classification
|
|
|
Describe Acid fast stain:
|
tests for mycobacteria (such as Tb and lepare-leprosy causing). Fatty surface not easily stained, so carbol fuchsin is used-red in color
|
|
|
What is differential staining so important?
|
better contrast (visualization) and classification
|
|
|
Negative staining
|
Stains capsule. makes background dark, capsule not stained by nigrosin but background is-produces halo looking cells
|
|
|
A sample was fixed and stained with carbol fuchsin and decolorized with acidic acid and countered with methylene blue, when examined many pink bacteria found, what does the patient problem have? Pneumonia, cold, HIV, syphilius, or Tb
|
Tb--stain tested possitive for a type of mycobacteria using the acid fast stain method
|
|
|
What kind of specialized cell structures can staining identify?
|
Spores (a differential stain using malachite green)-- clostridium and bacillus produce spores. Also flagella can be indentified using stains
|
|
|
Morphology:
coccus, Bacillus, vibrio, spirillum, spirochete, pleomorphic. Be able to indentify slides and pics |
sperical, rod shape, banana shape, curved spirals, tight spirals-corkscrew, cells with variable shapes
|
|
|
Cell groupings or arrangement:
Diplococcus, streptococccus, sarcina, staphyloccus. Be able to identify slides and pics |
Diplo= 2 cocci grouped together, strepto= chain, sarcina-packet or 4 together (really 8), staph- grape bunches or clusters
|
|
|
Multicellular associations
|
Biofilms and Associations
|
|
|
Biofilms
|
formed with a critical number or cells are present, irregular layers thick imbedded in extracellular slime they excrete. Important for infections, natural envir, and industrial processes
|
|
|
Associations
|
contains cells such as mycobacteria and filamentous bacteria, cells release extracellualr enzymes that can degrade organic material
|
|
|
Definition of Appendages
|
proteinaceous structures atttached to the cell surface: flagella fimbriae and pilli
|
|
|
Definition of Cell Envelope
|
various layers of the cell coat and surface, cell wall and cytoplasmic membrane
|
|
|
cytoplasm
|
structural and molecular compents enclosed by the cytoplasmic membrane
|
|
|
purpose of cytoplasmic membrane
|
defines the cell (shape-wise)
|
|
|
describe the structural composition of the bacterial cytoplasmic membrane
|
composed of phospholipid bilayer, the phospholipids sponateously arrange themselves into a sphere with two layers-hydrophobic tails and hydrophilic heads
|
|
|
phospholipid is composed of 3 main parts:
|
glycerol(binding element w/ester bonds), a phosphate head, and fatty acid as the chain tail end
|
|
|
integral proteins
|
aka transporter proteins are embedded in cell membrane (can move)
|
|
|
peripheral proteins
|
are loosely attached to the sides of the cell membrane
|
|
|
Fluid Mosaic Model
|
Cytoplasmic membrane and proteins in layer (the model that describes the make up and mobility of the membrane)
|
|
|
Special Functions of the prokaryotic cytoplasmic membrane
|
Aerobic respiration and photosynthesis, ATP synthesis (energy production) in Eukarya this would occur in mitochondria and chloroplast (but prokaryotes have no organelles)
|
|
|
Bacterial Membranes include
|
A fatty acidand glycerol with ester bonds (OH with COHC)
|
|
|
Archaeal membranes
|
Glycerol and Phytanol with ether bonds (2 alcohol). Also could be a monolayer alcohol at both ends
|
|
|
Cell Wall charcteristics of bacteria
|
rigid, shape determing, prevents lysis (no bursting in H20)
|
|
|
peptidoglycan
|
cell wall of bacteria have this layer, and it's a glycan chain linked together with a tetrapeptide x-linking
|
|
|
tire analogy for peptidogylcan layer
|
(assembled like a big cage) so areas for water to enter, so membrane/pepglycan layer is like an intertube and the cell wall is like a bike tire (think of resistance due to pressure)
|
|
|
the gram positive cell wall includes:
|
n-acetylmuramic acid, n-acetylglucosamine, Beta 1,4 gucosidic bond, glycan chain, x linking due to diaminopimelic acid has 2 amino groups
|
|
|
what is one of the most important enzymes for gram + bacterial cell wall assembly?
|
transpeptidase: catalizes the x-linking
|
|
|
G+ bacteria have
|
thick layer of peptidoglycan, small layer of periplasmic space where enzyme secreation occurs, teichoic acid, and a cytoplasmic membrane
|
|
|
teichoic acid
|
function not clearly known, but it does connect through peptdioglycan to the plasma (cyto) membrane
|
|
|
Gram - bacteria have a unique
|
outer membrane
|
|
|
describe layers of gram- wall
|
thick outer membrane with a lipopolysaccharide layer: made up of glucosamine and phosphate, then it has periplasmic space, a thin peptidoglycan layer, then plasma (cytoplasmic membrane)
|
|
|
describe the lipopolysaccharide
|
made of O-side chain (can be variable), a core polysaccharide in the middle, and a lipid (with a hydrophilic and hydrophobic region--phospate group and fatty acid)
|
|
|
porin
|
Porin llok like proteins fournd in outer membrane of Gram - cell walls and they are gate keepers, let things in
|
|
|
lipopolysaccharide is an ____
|
endotoxin, meaning that it can cause fever, even withought the bacteria inself, can cause no infection but animal/human would still get fever if it encoutners it
|
|
|
How does penicillin cause lysis of Gram+ bacteria?
|
Binds to transpeptidase (the x-linking enzyme of glycan chains) inhibits its activity, so bacteria can't assemble cell wall, during the binary fission step where split is occuring and cells only have 1 "wall" on their "house." Without their cell walls bacteria absorb water and burst (lysis)
|
|
|
How does penicillin effect Gram - bacteria?
|
It can cell both Gram + and - but it is not as effective because Gram - have outer membrane protection and a thinner layer of peptidoglycan, less dependence on transpeptidase for survival
|
|
|
Penicillin does/ doesn't effect archae
|
Does not effect archae
|
|
|
2 reasons crystal violet stains Gram + but not Gram -
|
Gram + have thick peptidoglycan layer that traps stain, Gram - has a thin layer that does not. Also alcohol removes outer membrane of Gram - therefore removing trapped stain
|
|
|
Mycobacteria's Outer Membrane
|
Bacteria of genus Mycobacterium have an outer membrane like Gram - but structurally it's different: no peptidoglycan, instead made of mycolic acid
|
|
|
Examples of Mycobacterium
|
tuberculosis and leprosy causing bacterium (GROW Slowly)
|
|
|
Acid-Fast staining
|
detects mycobacterium, isoniazide is an antibiotic agent that inhibits synthesis of mycolic acid
|
|
|
Know how to idenitify by pictures the G+, G-, and mycobacterium membranes
|
G+: 2 layers (thinnest/ no extra layers)
G-: thin layer of pepglyc, outer membrane Myco: thickest long lipids and acids visible |
|
|
Mycoplasma
|
small bacteria, can take any shape, wall-less bacteria, (examples STD-urethritis) also they do not lysis because of tough cytoplasmic membrane
|
|
|
Main differences of Archaea (vs Bacteria)
|
ssrRNA gene sequence (closer to eukarayotes), different cytoplamsic membrane structure (ether bonds-no FattyAcids), cell wall structure (no peptidoglycan
|
|
|
Pseudopeptidoglycan
|
some archaea have cell wall made of this (one of the 3 known options), different linkage (Beta 1,3, glycosidic bond) and different monomers
|
|
|
Polysaccharide layer cell wall
|
one of 3 options for archaea cell wall: thick layer of polysaccharide composed of glucose, glucuronic acid, galactosamine, and acetate
|
|
|
Protein (S-layer) cell wall
|
ONe of 3 options for archaea cell walls (paracrystalline surface layer consisting of protein or glycoprotein)
|
|
|
Penicillin is also an affective medicine in humans because unlike polymyxin that disrupts cell membranes
|
human cells have no cell walls so it wouldn't harm human cells yet it would kill many of the bacterial cells
|
|
|
the prokaryotic cytoplasm
|
composed of liquid cytosol, a natrix of proteins and water, and a chromosome ribosome and other inclusions
|
|
|
What takes palces in the cytoplasm
|
the cell's vital chemical reactions (metabolism)
|
|
|
Where is the chromosome of a bacterium cell found
|
in the nucleoid that is found in the nuclear region on the prokaryotic cytoplasm
|
|
|
What are Plasmids?
|
inclusions of the cytoplasm, circular 2x stranded DNA not required by cell, smaller than chromosome, only used for survival
|
|
|
storage granules (heavy polymers from usually limited nutrient) found in cytoplasm
|
volutin and PHB. Volutin are polyphosphate granules stored and used in times of phosphate deficiency. PHB (Fatty acid), also Glycogen -polymer of glucose
|
|
|
what are gas vesicles (cytoplasmic inclusion)?
|
some bacteria have gas permeable, water impermeable rigid sacs made of single protein, was to transport themselves to folat of sink, important for aquatic bacteria
|
|
|
What are endospores (cytoplasmic inclusion)?
|
found mainly in Gram + bacterial like Bacillus and Clostridium, resistant to heat desiccation toxic chemicals and UV light,can produce new cells grow and reproduce (anthrax agent)
|
|
|
Glycocalyx
|
slime layer and capsule included here, made of a gelatinous polysaccharide , capules are like camoflauge-can't easily be removed, distinct and well organized, slime layers wash off easily
|
|
|
Functions of glycocalyx
|
prevents drying out, protection fro phagocytosis (eating by other cells white blood cells) can stick to eachother to form biofilm
|
|
|
Compare and contrast appendages (ffp)
|
flagella, fimbriae, pili.Fagella is a long basal body responsible for motility with a hook and filament. Fimbriae are shortest and found all over bacteria (thin and short), pili is in between in sized and aids in conjugation
|
|
|
how are appendages of bacteria more or less effective than capsules
|
appendages used for spedific attachment (for finding hosts), capsule helps like a glue, non specific attachment
|
|
|
How can you distinguish flagellum on Gram + and -
|
negative has 2 bilayer rings on its basal body (LPSM rings) and Gram + has just one thin bilayer ring with the hook embedded
|
|
|
how do the flagellum rotate?
|
protn motive force, M-protien turn making filament turn
|
|
|
What kind of bacteria have no flagellum
|
spherical (cocci) "not good swimmers/ boat shape"
|
|
|
what are the three common types of arrangements of flagella on the cell surface
|
monotrichous/ polar flagellum (one tail), lophotrichous (one side), peritrichous (all around, many hairs_
|
|
|
what are endoflagella or axial filaments?
|
Spiochetes have enoflagella, bundles of flagella wrapped abroud cell body, endoflagella proell them like corkscrew (thick envir like mud)
|
|
|
What is Flagellin?
|
Flagellin is the protein that makes flagella, pili, and fimbriae
|
|
|
Do Fimbriae and pili help with cell motility
|
no
|
|
|
Fimbriae function
|
attachment (using help from adhesins
|
|
|
Pili
|
allow for movement of plasmid DNA from one cell to another, necessary for conjugation
|
