mirco exam
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Which of the follow are found in prokaryotic cells? Cytoplasmic Streaming, E.R.,
Golgi Bodies, Gas Vacuoles, Mesosomes, Mitochondria. - Gas Vacuoles and Mesosomes
- What are the three structural components make up a bacterial flagellum?
- Hook, Filament, Basal Bodies
- three functions/uses for a bacterial capsule.
- Desiccation, Phangocytosis, Attachment to some Surfaces
- The peptidoglycan layer is composed of chains that are cross linked. What is the composition of the chains and the x-linkers?
- The peptidoglycan layer is composed of chains with alternating NAM and NAG residues. The tetrapeptide dropping down from the NAM on one chain is x-linked to the tetrapeptide dropping down from the NAM on the adjacent chain by a pentaglycine chain.
- List the three main components of the gram negative cell’s outer membrane.
- LPS, Transmembrane Proteins, Phospholipids
- Which of the three components in the previous question is an endotoxin?
- LPS
- What is volutin and PHB granules made of?
- Volutin granules are made of polyphosphate and are a phosphate reserve. PHB (polyhydroxybutyrate) granules are made of a lipid-like material and serve as a carbon and energy reserve.
- How does a bacterial endospore differ from a bacterial cyst?
- Endospores are resistant to heat, stains, UV light, chemicals and desiccation and contain high concentrations of DPA, as well as produce inside the cell. Cysts are cells that have down sized are just desiccation resistant and have no DPA.
- Contrast passive diffusion of molecules into a cell versus active transport of molecules.
- Passive diffusion is with the concentration gradient and not regulated as much by the cells while active diffusion requires transmembrane proteins to take in or expel molecules against the concentration gradient.
- Contrast the purpose and composition of a growth medium with a maintenance medium.
- A growth medium has a large amount of nutrients to grow the cells quickly. A maintenance medium is low in nutrient content just enough to sustain the growth of the cells.
- What is a serial dilution and what is its purpose?
- A serial dilution is taking a sample of cells and putting it through a number of growth phases at different dilutions done by 10’s and seeing how many cells you can get to grow in the medium at high levels of dilution.
- You have preformed a spread plate count procedure to determine the bacterial dencity in the Galveston Ship Channel. If you plated 0.1 ml of each dilution into triplicate plated and the three 10^ -5 dilution plates after incubation yielded colony counts o
- 55+60+65 / 3 = 60 60x10 ^5 x 10 = 6x10 ^ 7
- The bacterial density you calculated in question above was probably an underestimation of the real value. Why was the calculated value wrong?
- Because it uses the Most Probable Number Test which provides an estimate not an actual count of the bacteria in the sample
- How would you define a pure culture?
- A pure culture is one of uniform size, color, shape and growth
- Define the term facultative anaerobe.
- Can live in both aerobic and anaerobic zones but does best in aerobic