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Bacteriology at UW-Madison |
1. What is a microorganism? In what ways are microorganisms different from higher (multicellular) organisms?
2. What are the major differences between eukaryotic and procaryotic cells? Which microorganisms are eukaryotic? Which are procaryotic?
3. What are the properties of viruses? How do viruses differ from all type of cells? Why are viruses called obligate intracellular parasites?
4. What, according to Woese, is the molecular basis for the establishment of three cellular Kingdoms (or "Domains"): Archaea, Bacteria and Eukarya? Distinguish the three cell domains on the following basis: a. nuclear organization; b. cell membrane lipids; c. cytoplasmic organelles (chloroplasts, mitochondria, etc.); d. murein in cell wall; e. chromosome number and topology; f. ribosome size; g. initiation of protein synthesis; h. sensitivity to diphtheria toxin, chloramphenicol and streptomycin (explain).
5. Compare Haeckel's phylogenetic tree of 1866, Whittaker's 5-Kingdom System of 1969, and Woese's phylogenetic tree of 1986? What is the objective and purpose of these schemes? In each scheme what are the criteria for organization of the cellular forms of life. In each scheme, where do the procaryotic and eukaryotic microorganisms fit?
6. Why are viruses not mentioned in any of the classification schemes above? Where would you fit viruses into each of the schemes. Where would you fit Archaea into the Haeckel and Whittaker schemes?
7. What molecular and biochemical evidence suggests that eukaryotic mitochondria and chloroplasts have evolved from procaryotic cells which either invaded, or were captured by, primitive nucleated cells? What groups of contemporary bacteria are related to chloroplasts and/or mitochondria?
8. Contrary to the popular theory of endosymbiosis (above), might it be possible that procaryotes evolved from chloroplasts and/or mitochondria which escaped from eukaryotes towards a free-living existence?
9. What are the main ways that the microorganisms impact the ecology of humans. Consider both free-living microorganisms and those that live in intimate associations with humans. What are the most beneficial and harmful effects of bacteria on humans?
10. How are procaryotes indispensably involved in the cycles of elements that make up living systems? Consider, in particular, the carbon, nitrogen and oxygen cycles?
11. What are the chemical elements that predominate in all living systems? In what cellular materials are these elements found?
12. What are the major classes of biologically important macromolecules and what are their subunits composed of? In what compartments or structures of bacterial cells are these macromolecules located?
13. Draw a typical bacterial cell and identify all parts and structures.
14. What is the typical size of a bacterium, e.g. Escherichia coli or Staphylococcus aureus? What are the typical shapes and groupings of bacteria when viewed with the light microscope? Name several genera of bacteria that are named for their characteristic shape or grouping.
15. List the location, composition and function of each of the following bacterial structures.
16. What are the similarities and differences between bacterial fimbriae and flagella?
17. What arrangements of flagella are found on bacteria? Is there any taxonomic value in determining the presence or absence of flagella, or in knowing flagellar arrangements? Can you see bacterial flagella with a light microscope? How could you demonstrate that a bacterium has flagella? How could you demonstrate that flagella are responsible for bacterial swimming movement? What are the differences between bacterial flagella and the flagella or cilia of eukaryotic cells?
18. Illustrate or describe the ultrastructure of the bacterial flagellum as revealed by electron microscopy. Explain how the flagellum operates to impart movement to a bacterial cell. What are chemotaxis, phototaxis, aerotaxis, and magnetotaxis, and what do these processes have to do with flagella?
19. What is the distinction between a true capsule, a slime layer and a glycocalyx. Apparently, in nature, all bacteria produce a glycocalyx, even though they do not form this structure when growing in tubes and plates in the laboratory. Why do you think this is the case?
20. How do the functions of fimbriae (also called common pili) overlap with the functions of capsules and glycocalyx? Why might the functions of these bacterial structures be similar?
21. Give an abbreviated formula for the muropeptide subunit of the peptidoglycan of E. coli and Staphylococcus aureus. Give the meaning of any abbreviations that you use. What are the similarities and differences in the two types of murein? Point to the bond in murein that is destroyed by lysozyme and to the bond whose synthesis is blocked by penicillin.
22. Identify these structural components in the cell wall or cell "envelope" of certain bacteria: peptidoglycan sheet, lipopolysaccharide layer, lipoprotein, teichoic acids, interpeptide bridge. Identify these chemical components: N-acetylmuramic acid, D-glutamate, D-alanine, diaminopimelic acid, L-lysine, pentaglycine bridge, Lipid A, ketodeoxyoctonoic acid.
23. What accounts for the rigidity and strength of bacterial cell walls?
24. What are the differences between the cell walls of eubacteria (Bacteria) and archaebacteria (Archaea)? Describe the similarities and differences between the cell walls of Gram-positive and Gram-negative eubacteria.
25. Penicillin is known to be most effective against Gram-positive bacteria that are actively multiplying. Why is this so? Archaebacteria are resistant to the action of penicillin. Why is this so? Many Gram-negative bacteria are inherently resistant to natural penicillin. Why is this so? Most strains of the human pathogen Staphylococcus aureus are resistant to the action of penicillin. Why is this so?
26. What is lysozyme? Where is it found in nature? What is the effect of lysozyme on eubacteria and what is its mechanism of action?
27. Identify the location and function each of these components of the outer membrane of E. coli: phospholipid, lipopolysaccharide, Lipid A, O-polysaccharide, Mg++ bridges. ompC. and ompF porins, Braun lipoprotein, OmpA protein. What is the function of the outer membrane to the bacterium.
28. Illustrate and discuss the fluid mosaic model of a biological membrane? What accounts for the "double track" appearance of membranes in electron micrographs?
29. Compare the macromolecular structure and organization of the eubacterial membrane with the archaebacterial membrane. Compare the composition of the eubacterial plasma membrane with the Gram-negative bacterial outer membrane.
30. What are the characteristics or components of bacterial membranes that account for these functions?
31. What constitutes a transport system in the bacterial plasma membrane? What is meant by active transport of a solute? Why do most bacteria have a need for active transport systems? What is the fundamental distinction between transport of a solute by active transport (ion-driven transport or binding protein-dependent transport) vs. group translocation? Is there any advantage in the latter process.
32. Compare the transport systems of bacteria, facilitated diffusion (FD), ion-driven transport (IDT), binding protein-dependent transport (BPDT), and group translocation (GT) on the following bases: carrier proteins involved, specificity, ability to concentrate solutes against the gradient, requirement for energy.
33. Identify several types of reserve materials stored as inclusions in bacterial cells. What is the advantage to the cell of storing reserves as polymerized molecules rather than in a monomeric subunit form?
34. What is the function of the structure and function of these types of inclusions in bacterial cells?
35. How are bacterial endospores structurally and chemically different from the vegetative cells that form them? What sorts of bacteria form endospores? What are the properties of endospores which allow them to be characterized as the most durable living things on Earth?
36. Describe the morphology, habitat(s) and some distinguishing features of the following important groups of procaryotes (identified by informal names):