Lecture 51. Compare and contrast capsule and slime layer a. Capsule: Semi-rigid, defined border, excludes india ink particles, firmly attachedb. Slime layer: Non rigid, does not exclude india ink, loosely attached to envelope, can be lost from surface, if lost can cause bacteria to become evirulent2. Identify a capsule or slime layer on a microscopy picture 3. List the functions of capsule and slime layera. Water retentionb. Protectionc. Cell- aggregationd. Adhesione. Pathenogensisf. Biofilm formation 4. Compare and contrast fimbriae/pili with flagella a. Fimbriae- short thinner, more numerous, no wave periodicity5. Explain three well-established functions of fimbriae/pili a. Adhesion to specific carbohydrates on cell surface with tissue and host selectivityb. Important in virulencec. Sex pilusd. Twitching motility6. Explain the tissue and host selectivity of fimbriae/pili adhesiona. Adhesion to specific carbohydrate tissues and host 7. Explain the function of the sex pilus in bacterial conjugation a. Some bacteria have an F plasmid which encodes for the sex pilus b. Sex pilus will recognize cells that do not have the F plasmidc. Sex pilus will react and cells come into contact two cells exchange DNA at this point8. Explain why bacterial motility is important for survival a. Competition for food, adaptation or dispersionb. Importance of dispersal when unfavorable conditionsi. Nutrient limitationii. Accumulation of waste productsiii. Escape predatory/ host defensive activities9. List the parts of flagella and their functions a. Filament- rigid helix of constant width, variable length, hollow filament of single subunit, functions as propellerb. Hook- short curved hollow filament that connects the filament to the basal body, universal jointc. Basal body- Hollow central rod rotates and transmits rotation to rest, basal body is just inside the cell surface. Motor proteins decide speed switch proteins (Fli)-decide park, reverse, forward10. Label the parts of a flagellum on a drawing of the flagellum 11. Explain how the cell assembles the flagellum a. Assembles basal body, then hook, then filament. Starts in cytoplasmic membrane, all proteins there, then to get to the assembly they go through the hollow inside of the flagella. Hook cap builds then comes off when complete, like a building crew.12. Explain what form of energy fuels the rotation of the flagellum, how it fuels the rotation, and how the speed of rotation is controlled a. Fueled by the PMF H+ travels through the Mot proteins b. Electrostatic interactions with ms and C rings cause rotationc. 1,000 protons must be translocated for one turn speed varies based on strength of PMF13. Explain how bacteria with peritrichous flagella move a. CCW- helical wave propels the cell forwardi. Bundled flagella rotate togetherb. CW- unbundles the flagella, cells tumblei. Resumed CCW rotation propels the cell forward in a new direction14. Compare and contrast the movements of bacteria with reversible and unidirectional polar flagella a. Reversiblei. CCW rotation- forward movementii. CW rotation- backward movementiii. Reorientation by Brownian motionb. Unidirectionali. Only turn CW and push the cell forwardii. After stopping, cells reorient by Brownian motion15. Compare and contrast bacterial tumbling and Brownian motion a. Tumbling- Reorientation because of clockwise motionb. Brownian- Random drifint of particles suspended in liquid or gas16. Compare and contrast bacterial random walk and directional movement a. Random Walki. Tarnsient forward runs interrupted by short tumblesb. Directionali. Chemotaxis random walk becomes biased in response to the chemical gradient runs are smoother and longer, cells swim up the gradient of the attractant c. Repellanti. Tumbles more frequent and runs shorter17. Describe Adler’s capillary experiment a. Chemical diffuses; Gradient from inside to outsideb. Observes where bacteria are going; Measures concentration of cellsc. 1. Attractd. 2. Rearrange randomlye. 3. Repellent18. Explain the mechanism of bacterial chemotaxis a. Sensory protiens (chemoreceptors) in the cytoplasmic membrane, and cytoplasmic proteins regulate the flagellar motor rotationb. Chemoreceptors specifically bind chemicals, sensing their presence and their change in concentration over timec. Chemotaxis response includes modifications of the chemotaxis proteins19. Describe phototaxis and aerotaxis a. Phototaxisi. Many phototrophic microorganisms can move toward lightb. Aerotaxisi. Other microorganisms can move toward or away from
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