Micro Study Guide 2
Micro Study Guide 2 MICRO 3050
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This 12 page Study Guide was uploaded by Ashton Holley on Tuesday January 19, 2016. The Study Guide belongs to MICRO 3050 at Clemson University taught by Dr. Rudolph in Winter 2016. Since its upload, it has received 58 views. For similar materials see General Microbiology in Microbiology at Clemson University.
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Date Created: 01/19/16
UNIT 2 STUDY GUIDE Spring 2016 MICR 3050 OBJECTIVES: Chapter 3.1 – 3.5 1. Compare and contrast the structure, composition, and functions of the cell walls of gram-positive and gram-negative bacteria. Be able to label them. Gram Positive: -90% peptidoglycan -may contain large amounts of teichoic acids (negative charged) ~maintain structure of cell envelope ~protect from harmful substances ~may bind to host cells (pathogenic bacteria) -lipoteichoic acids ~attached to membrane lipids - some have proteins on surface of peptidoglycan Gram Negative: -thin pept wall surrounded by outer membrane -outer memb composed of lipids, lipoproteins, and lipopolysaccharide (LPS) -NO techoic acids - about 10% peptidoglycan -periplasm (20-40% of cell volume) ~many enzymespresent in periplasm: hydrolytic enzymes, transport proteins, and other proteins -outer memb lies OUTSIDE of pept layer -Braun’s lipoproteins connect outer memb to pept 2. Describe the effects of lysozyme and penicillin on a bacterial cell wall. Lysozyme: breaks the bond betw NAG and NAM Penicillin: inhibits pept synthesis --if cells are treated with either of the above, they will lyse if they are in HYPOtonic ssolution 3. Explain how bacteria may survive without a cell wall. -survival in isotonic environments -protoplasts -spheroplasts -Mycoplasm -no cell wall -plas memb more resistant to osmotic pressure 4. Describe capsules and slime layers and discuss their functions. Capsules: -usually composed of polysaccharides -well organized & not easily removed from cell -protective: ~ resistant to phagocytosis ~protect from dessication ~ exclude viruses and detergents Slime Layers: -similar to capsules except—unorganized & easily removed -may aid in motility Chapter 3.6 – 3.9 5. Describe the following bacterial structures and their functions: cytoskeletal proteins, cell inclusions, fimbriae, pili, flagella, and endospores. Cytoskeletal proteins: found in cytoplasm (which is pretty organized), role in cell divisions, protein localization, & determination of cell shape Ex: ~Ftsz: proteins involved in cell division, line up in middle of cell and form the division plane ~MinD: gives a place for Ftsz to bind—helps it divide evenly & makes sure Ftsz line up in the middle ~MReB: gives a rod shape the gene was mutated: bacillus would become cocci Inclusions: found in all cell types -aggregates of organic or inorganic material ~granules ~crystals ~globules -some are enclosed by a single layered “membrane” or invaginations of plasm memb—not a true memb bound organelle—could be surrounded by proteins -Storage Inclusions: storage of nutrients, metabolic end products, energy, building blocks ~Carbon (-glycogen -PHB) ~Phosphates (-polyphosphate granules) ~Sulfur Globules ~Nitrogen (-cyanophycin granules) -Other Inclusions: gas vacuoles (provide buoyancy), magnetosomes (magnetic particles for orienctation in Earth’s magnetic field) External Structures: extend beyond the cell envelope in bacteria & archaea, functions: protection, attachment to surfaces, horizontal gene transfer, cell movement. -fimbriae, pili, and flagella Fimbriae and Pili: hollow tubes, short, thin, hairlike protinaceous appendages (up to 1,000 per cell), mediate attachment to surfaces, some (type IV pili) required for motility or DNA uptake -Sex Pili: similar to fimbriae except longer, thicker, & less numerous (1-10 per cell), genes for formation found on plasmids (sometimes chromosomes), required for conjucation Flagella: threadlike appendages extending outward from plasm memb & cell wall, functions: motility & swarming behavior, attachment to surfaces, may be virulence (deadly) factors (help them be better pathogens Endospores: 6. Describe flagellar structure and movement. Patterns of Flagella Distribution: (arrangement of flag is species specific, very few cocci have flag but bactillus and spirilla mostly do) - monotrichous- 1 flag - polar flagellum- flag at end of cell - amphitrichous- 1 flag at each end of cell - lopotrichous- cluster of flag at 1 or both ends - peritrichous- spread over entire surface of cell Structure: - filament (hollow tube) - hook (single filament that holds the filament to the motor) - basal body (motor) (mot proteins- stationary, help determine on/off & rotation direction) (4 rings in gram negative: 1. LRing: LPS layer 2. PRing: peptidoglycan 3. CRing: cytoplasm(little into it) 4. MS: above, high up on memb) (2 rings for Gram positive: 1 attached to pept and 1 to memb) 7. Define chemotaxis and describe how bacteria move toward an attractant (or away from a repellent). Chemotaxis: movement toward a chemical attractment (toward food, O2) or a away from a chemical repellent (toxins) -concentrations of chemoattractants& chemorepellants detected by chemoreceptors on surface of the cell (cell membr)—detect chemical changes in the environment & make responses -complex but rapid—responses occur less than 20 milliseconds, 2 to over 60 cell length per second Positive/ Negative Chemotaxis: -toward: caused by lowering the frequency of tumbles -runs in direction of attractant are londer -biased random “walk” -away: involves similar but opposite responses *** cant turn or run indefinitely—can only run straight to something, cant turn- so they must tumble: if they are running something they really want, they: decrease # of tumbles & increase run time; if something they don’t like: increase tumbles & decrease run time 8. Describe other types of motility (spirochete, twitching, and gliding). Spirochete: like sypholis (wants to attach to host tissues) -multiple flag form at axial fibril which wings around bact cell (inside the periplasm- spinning inslide of cell) -flag remain in periplasm space inside outer sheath -corkscrew shape exhibits flexing & spinning movements Twitching and Gliding: may involve type IV pili or fumbrial— may be used to grab onto cell surface- looks like they’re twitching -twitching: pili at ends of cell short, intermittent jerk motions cellsa re in contact w/ eachother & surface -gliding: smooth movements 9. Understand the structure and functions of bacterial endospores, the basics of sporulation and germination, and endospore resistance. Endospore: complex, dormant structure formed by some bact when it can no longer grow (bc of weather, food supply, too much O2)—triggers sporulation- dormant structures (like a seed or spore) that hangs around (can be years) until conditions are goon enough for it to grow—cell DOES die to make spore -various locations w/in cell -resistant to numerous environmental conditions: heat/boiling, radiation (Gamma & UV), chemicals (don’t penetrate bc of extra layers), desiccation (don’t need water, don’t have to metabolize) - to kill endospore: autoclave (steam pressure) at 120degC for 10 min Structure: we study Gram positive, when spores germinate, it loses layers, only keeps germ cell wall and inner memb - exosporium: outside protective covering - spore coat: very thick of proteins, help be impermeable to toxins - cortex: pept (crosslinked) - core: very dehydrated Makes them resistant: -core: like cytoplasm ~ low water content (dehydrated=resistant to things) ~ calcium diplocolinate (Ca-DPA—inserts in the bases of DNA to protect from denaturing) ~ SASPs: small, acid soluble DNA-binding proteins, protect DNA by saturating them=protection from denature ~slightly lower pH (enzymes that aren’t working) -lysozyme: endospore are resitant to it Sporulation: (down)- making the spore & releasing the spore due to lack of nutrients -depends on species when spore is made -dormant form by dehydration -look at diagram in slides - sheds outside layer Germination: (around)- dormant if spore goes back to vegetative cell in good conditions, determined by nutrients being detected Formation of Vegetative Cell: -bringing in water loses resistance -Activation: prepares spores for germination; often results from treatments like heating -Germination: environmental nutrients are detected; spores swelling& rupture of spore coat; loss of resistance; increased metabolic activity -Outgrowth: emergence of vegetative cell Chapters 11.1, 10.1 – 10.4 10. Know the requirements for microbial survival and growth and their sources. -source of E: for cellular work -source of e-: play a role in E production; reduce CO2 to from organic mlcs (e-s hold reducing power:reduction=gaining of e-) -nutrients: Carbon, Hydrogen, and Oxygen: to synthesize organic building blocks needed for cell maintenance & growth; for building macromlcs for growth & repair e- and E Sources: 1. Organic or inorganic chemical compounds (E is obtained by oxidizing (breaking down the substance/ removing e-s from) a cmpd 2. sunlight (E only) -E is usually conserved in cells as adenosine triphosphate ATP (E only bc inorg and org cmpds are typically same sources used for e-, but you cant get e- from sunlight bc photons don’t have e-… if you use sunlight for E you need e- elsewhere) 11. Define and recognize the major nutritional types of microorganisms based on their energy source, electron source, and carbon source. -Based on E source ~phototrophs use light ~ chemotrophs obtain E from oxidation of chemical cmpds -Based on e- source ~lithotrophs used reduced inorg substances ~organotrophs obtain e- from org cmpds -Based on Carbon source ~heterotrophs- use org mlcs as C source (which often serve as E & e- source as well) ~autotrophs- use CO2 as their sole or principle C source -must obtain E and e- from other sources -primary producers ** CO2 is the most oxidized form of C in nature—cant use it as an e- source, only C source 12. Define metabolism, catabolism, and anabolism. Metabolism: total of all chemical rxns occurring in the cell *** need macros- get them from 3 diff sources: 1. metabolite- product of metabolism 2. ATP used in all steps 3. Reducing power from e- comes in to help w/ E production to give monomer building blocks that help w/ macromlcs that come together from bact Two parts of metabolism: catabolism and anabolism! Catabolism: -get building blocks, E, & e- - fueling rxns -E-conserving rxns - provide reducing power (e-) - generate precursors for photosynthesis Anabolism: - the synthesis of complex org mlcs from simpler ones gathered in catabolism - requires E & building blocks from fueling rxns 13. Understand the concepts of free energy (G) and standard free energy change ( G ). ENERGY AND WORK: ***available after a chemical rxn has completed- whatever E is left over can be used for work Energy: capacity to do work or cause particular change - G= free E (the amt of E that is available to do useful work) Types of work carried out by microorgs: - chemical- synthesis of new cellular material - transport- take up of nutrients, repair & replace, elimination of wastes, & maintenance of ion balances - mechanical- motility of cells, chemotaxis o Standard Free E: ( G ) -standard free E change at pH 7, temp of 25 deg C, 1 atm, reactants & products at 1 M concentration 14. Distinguish between exergonic and endergonic chemical o reactions and their relationship to G . Exergonic: release E - A+B yields C+D+Energy o - G is (-): rxn proceeds spontaneously - occurs w/ extra E input Endergonic: require E - A+B+Energy yields C+D - G is (+): rxn will NOT proceed spontaneously - no E released - need input of E to make rxn occur 15. Explain the importance of ATP. ATP: - about 31 kJ/mol (abt 7.3 kcal/mol from breaking off a phosph from ATP) of E is released when ATP is hydrolyzed to ADP+Pi (1kcal= nutritional calorie, 4184 Joules) - about 46 kJ/mol of E is released when ATP hydrolyzed to AMP+ 2Pi - 3 phosphates (remove 1 off of ATP=ADP-creates release of E) - high phoph transfer potential bc it commonly breaks off the phosphate to give other mlcs (glycolysis, glucose-6, phosph… all from ATP-makes it a good mlc for E storage) - breaking squiggly bond= gaining more E than a normal covalent bond; doesn’t mean its difficult to break, however-pretty easy to make ATP in cell for storage & pretty easy to break those bonds - breaking the 2 phosph releases collectively (btw the 1 & st nd 2 ) 46 kJ/mol- doesn’t couple the E from breaking off the 1 (31 kJ/mol)- you don’t get 62 kJ/mol - closer to phosphate is to the mlc= the tighter the hold; takes more E to break, releasing E in return; has to do w/ mlc stability 16. Be aware of other high-energy compounds, and know the change in standard free energy requirement for cells to use them. Oxidation/Reduction=Redox rxns: - conserve E in the form of ATP or other E righ cmpds - many metabolic processes involve redox rxns (e- transfers) - e- carriers are often used to transfer e- from an e- donor to an e- acceptor - can result in E release, which can be conserved as ATP or another E-righ cmpd - frequently involve the transfer of not just e- but both an e- plus a proton (H+) Oxidation: - removal of an e- (or e-s) from a substance Reduction: - addition of an e- (or e-s) to a substance 17. Understand redox reactions including the standard reduction potential (E0) of half reactions, the electron tower, and their relationship to G . Standard Reduction Potential (E ): 0 - equilibrium constant for an oxid-red rxn - a measure of the tendency of the reducing agent to loss e- ** more (-) E 0= better e- donor **more(+) E 0 better e- acceptor 18. Describe the location, organization, and functions of the Electron Transport Chains in bacteria. E Tower: - the greater the diff btw the E 0 of the donor and the E 0 of the acceptor= the more (-) G o - standard reduction is released to free E change - higher diff btw voltage= more E released - O2= best acceptor - Baby screams louder as it does to the bottom & then there is more E released as they go down - Foes from red to oxid - Is more red if more H+ E and e- flow in metabolism: - flow of e- down the tower releases E - light E is used to drive e- up the tower during photosynthesis e- transport Chain: - e- carriers organized into ETC w/ the 1 e- carrier having the most (-) E0 st ~ the pot E stored in the 1 redox couple is released & used to form ATP ~ 1 carrier is reduced & e- moved to the next carrier & so on -the net E change of the complete rxn sequence is determined by the diff in reduction potentials btw the primary & final acceptor - christa- inside mitochondria; bact don’t have mitochondria so use plasma memb 19. Define the two classes of electron carriers. Two classes: Coenzymes: freely diffusible; can transfer e- from one place to another in the cell (ex. NAD) Prosthetic groups: firmly attached (fixed) to enzymes in the plasma memb; fxn in memb- associated e- transport rxs (ex. Cytochoromes) 20. Describe how NAD /NADH and NADP /NADPH carry electrons and their roles in metabolism. NAD+: nicotinaminde adenine dinucleotide (nanny) NADP+: nicotinamide adenine dinucleotide phosph (w/out e- s/oxidized) NADH & NADPH: are good e- donors (reduction pot of redox couples in -0.32 V) NAD+/NADH: works the same way except involved in ana - coenzymes- freely diffusible - carries 2 e- plus 1 H+ (1 H+ is released) - involved in catabolism ***NADp+.NADPH works the same way except involved in anabolism DISEASES Strep Throat (Streptococcal pharyngitis) -cause: group A beta-hemolytic streptococcus - characteristics: coccus, gram(+) - transmission: close contact w/ infected person - symptoms: sore throat, fever, enlarged lymph nodes Cholera -cause: Vibrio cholerae (bacterium) - characteristics: gram(-), vibrio: comma-shaped -transmission: consuming contaminated water or food (fecal contamination) - symptoms: bad diarrhea and vomiting- dehydration Bacterial Meningitis -cause: Neisseria meningitidis - characteristics: gram(-), diplococcus - transmission: direct close contact with discharges from the nose or throat of person who is infected - symptoms: loss of motor fxn, respiratory tract symptoms, stiff neck Lyme Disease -cause: bact from genus Borrelia-- Borrelia burgdorferi - characteristics: gram(-), spirochete -transmission: ticks, from blood - symptoms: not all who have it show symptoms- if symptoms: flu-like, bulls-eye rash, joint pain Infectious Monocucleosis **better known as Mono -cause: Epstein-Barr virus (EBV) -characteristics: core with spikes and envelope -transmission: kissing, through saliva, sneezing -symptoms: fever, sore throat, tiredness, inflamed lymph nodes Gas Gangrene -cause: C. perfringens -characteristics: gram (+), streptococcus, Staphylococcus aureus, Vibrio vulnificus -transmission: direct contact with bacteria -symptoms: produces gas in tissues/swollen wound, very sudden, infected area is inflammed
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