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Micro Exam 10/5
1st Micro Exam
| Question | Answer |
|---|---|
| What are Koch's Postulates? | 1. Must be present in every case of the disease, but not in healthy individuals 2. Must be isolated and grown in a pure culture 3.The same disease must result when healthy individual is inoculated with organism 4. Must isolate from inoculated individua |
| Why can't we use all of Koch's postulates today? | Some organisms cannot be grown in a pure culture, inoculating a healthy human is unethical, may be replaced by genetic and molecular evidence, some individuals may be naturally immune to the disease |
| What produces an image in dark field microscopy? | Only the light refracted by the object. |
| What is dark field good for? | Internal structure in live, unstained cells |
| What does phase contrast do? | Changes differences in refractive indexes into variations of light intensity |
| What does differential interference contrast microscopy do? | Uses 2 beams of plane polarized light to form a colored, 3D image |
| Transmission EM | uses electrons that pass through an organism to form an image: shape and fine details of organelles |
| Scanning EM | Forms image from electrons released from organism’s surface: 3D detailed image |
| Confocal | Focuses light from all areas of the object, not just the plane of focus |
| Scanning Probe | Move a sharp probe over the electron cloud, apply a small voltage between the two, this current is sensitive to distance |
| What are the 3 parts of a lipopolysaccharide? | 1. Lipid A 2. Core polysaccharide 3. O side chain |
| Where is an LPS located? | Embedded in the outer membrane |
| What charge does LPS give to the cell surface, what does this do? | Negative, help attach to surfaces and form biofilm |
| What does LPS contribute to the cell? | Stability, permeability barrier, protection, can act as an endo toxin |
| What substance forms capsules and slime layers? | Glycocalyx |
| Diplococci | pairs |
| Streptococci | Chains |
| Staphylococci | grape-like clusters |
| Tetrads | 4 cocci in a square |
| Sarcinae | cubic configuration of 8 cocci |
| Cocci | spheres |
| Bacilli | Rods |
| Vibrios | comma shaped |
| Spirilla | rigid helices |
| Spirochetes | flexible helices |
| Mycelium | network of long, multinucleate filaments |
| Palisades | grid-like |
| Pleomorphic | Organisms that are variable in shape |
| Which 2 cell envelope components make up the cell wall? | Peptidoglycan and the outer membrane. |
| Fluid mosaic model | The idea that membranes are lipid bilayers in which proteins float |
| Amphipathic | contains both polar and non polar ends |
| Peripheral proteins | Loosely connected to the membrane, easily removed |
| Integral proteins | Not easily removed from membrane, insoluble in aqueous solutions |
| Hopanoids | Like steroids, help stabilize membrane |
| Protoplast | The plasma membrane and everything w/in it |
| Inclusion bodies | granules of organic and inorganic material suspended in the cytoplasm, used for storage and reducing pressure |
| Where are proteins synthesized | Ribosomes |
| Nucleoid | Irregularly shaped region containing the bacterial chromosome |
| Plasmid | small, double-stranded DNA molecules that exist independently of the chromosome |
| What is the Periplasmic space? | area between plasma membrane and cell wall |
| What two substances make up peptidoglycan? | N-acetylglucosamine and N-acetylmuramic acid |
| Which type of bacteria has teichoic acids? | Gram (+) |
| Teichoic acids | Help give gram (+) cell wall its negative charge |
| Braun's lipoprotein | Links outer membrane to peptidoglycan |
| Sec-dependent | Secretion dependent, the main pathway for transporting proteins across the plasma membrane |
| What is it called when a cell has an outer layer that is clearly defined and not easily removed? | Capsule |
| Slime layer | Zone of diffuse, unorganized material that is easily washed off a cell |
| Fimbriae | Short, fine, hairlike appendages, thinner than flagella |
| Pili | 1-10 per cell, larger than fimbriae, required for conjugation (sex pili) |
| What are the parts of a flagella? | Flagellar filament, basal body, flagellar hook |
| Flagellar filament | Part of a flagella that extends from the edge of the cell surface to the tip |
| Basal body | Part of the flagella that is embedded in the cell |
| Flagellar hook | Links the filament to the basal body, acts as a flexible coupling |
| Describe flagellar motion | The flagella is shaped like a helix, which rotates the cell and moves it forward |
| Monotrichous | One flagellum |
| Polar flagellum | A flagellum located at one end of the cell |
| Amphitrichous | Flagellum at each pole |
| Lophotrichous | Cluster of flagella at one or both ends |
| Peritrichous | Flagella evenly spread all over |
| What is the purpose of an endospore | Survival under harsh environmental conditions |
| What is in the Periplasmic space? | Contains hydrolytic enzymes and binding proteins for nutrient processing and uptake |
| Heterotroph | Organisms that use reduced, pre-formed organic molecules as their carbon source |
| Autotrophs | Organisms that use CO2 as their sole or principal source of carbon |
| Phototrophs | Use light as their E source |
| Chemotrophs | Obtain E from oxidation of chemical compounds, can be organic or inorganic |
| Cemoorganotrophs | Obtain E from oxidation of organic compounds |
| Chemolithotrophs | Obtain E from oxidation of inorganic compounds |
| How do bacteria obtain inorganic Fe? | Siderophores |
| What are some examples of growth factors? | Vitamins, amino acids, purines, pyrimidines |
| Synthetic media | All components and their quantities are known |
| Complex media | contains some components of unknown compositions |
| What are the types of media? | General purpose, enriched, selective, differential |
| Enriched media | Added growth factors |
| Passive diffusion | Molecules move from an area of higher concentration to an area of lesser concentration |
| Facilitated diffusion | Involves "carrier molecules" to increase the rate of diffusion |
| Active transport | metabolic energy required to move substances against a concentration gradient |
| What are the two types of active transport? | Symport, anti-port |
| Symport | Active transport of two molecules in the same direction |
| Anti-port | Active transport of two substances in opposite directions |
| Group translocation | modifies molecules as they enter the cell |
| Permeases | Carrier proteins |
| ATP-binding cassette transporters | Active transport system, consists of 2 hydrophobic membrane-spanning domains with 2 ATP binding domains |
| Selective media | favors the growth of one particular organism |
| Differential media | distinguishes among different groups of microbes and permits tentative identification |
| Pure culture | Population of cells arising from a single cell |
| Spread plate | Spread a dilute solution containing the organism over a plate of media |
| Streak plate | What we do in lab, use a loop to streak a small amount over the plate to achieve isolated colonies |
| Pour plate | Original sample is diluted several times to obtain isolated organisms when poured into a plate |
| What are the basic structures of a monosaccharide? | One carbon ring with hydrogens and oxygens bonded to it |
| How do bacteria use carbohydrates? | As glycoproteins, which are receptors for the cell, they also form glycocalxy, which produces capsules and slime layers, also used in respiration |
| How do microorganisms use lipids? | They use them for structure and as an energy source because of the high energy bonds present |
| How do microorganisms use cholesterol? | Provides structure and support |
| How do microorganisms use phospholipids? | Provide structure and protection, make up the cell membrane |
| What are the 3 parts of an amino acid? | An amine (-NH2), carboxyl groups (-COOH) and and R group |
| How many amino acids are needed to make a protein? | At least 30 |
| Acid fast bacteria | Resistant to simple acids, also hard to break down with anti-microbials |
| What form of cell division do bacteria use? | Binary fission |
| What defines microbial growth? | Increase in cellular constituents, increase in organisms size, population size or all 3 |
| Why is the initial phase of growth called the "lag phase"? | Because there is no immediate increase in population size because the cell is synthesizing new components needed for growth |
| What are the stages of cell growth in order? | Lag phase, exponential phase, stationary phase, death phase |
| At what salt concentration do Halophiles grow? | >0.2M |
| Which extremophiles grow at salt concentrations of 2M - 6.2M? | Extreme halophiles |
| What are the 3 ways to classify bacteria with respect to pH? | Acidophiles, neutrophiles, alkaliphiles |
| At what pH range do acidophiles thrive? | 0-5.5 |
| At what pH range do neutrophiles thrive? | 5.5-7 |
| At what pH range do alkaliphiles thrive? | 8.5-11.5 |
| What are the 5 ways of classifying bacteria with respect to temperature? | Psychrophile, psychrotroph, mesophile, thermophile, hyperthermophile |
| Fluorescence Microscopy | Exposes organisms to ultraviolet, violet, or blue light then forms an image from the resulting fluorescence |
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