Microbiology Study Guide For Exam 2
Microbiology Study Guide For Exam 2 3050
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UNIT 2 STUDY GUIDE for LECTURE TOPICS MICR 3050 for Majors Spring 2016 OBJECTIVES: Chapter 3.1 – 3.5 1. Compare and contrast the structure, composition, and functions of the cell walls of gram positive and gramnegative bacteria. Be able to label them. Gram positive i. This cell wall is composed of mainly peptidoglycan 1. Prevents the cell from lysing and helps the cell have turgor pressure 2. If you could hug a bacterial cell it would feel like a car tire 3. Also contributes to the pathogenicity as well as provides protection form toxins 4. Finally it gives the cell it shape! Remember if the cell does not have a specific gene for the shape of the cell, it will be round! 5. More on peptidoglycan in a moment ii. Very thin periplasmic space and then the plasma membrane iii. Most pep is 90% iv. Large amounts of techoic acids only found in gram positive cells negatively charged too 1. Maintain the structure of the cell envelope 2. Protection form harmful substances 3. May bind to host cells pathogenic bacteria v. Lipotechoic acids attached to the cell membrane 1. Some gram positive cells have proteins on the peptidoglycan. vi. Gram Negative i. Outer Membrane which has a bunch interaction functions but mainly focuses on the protection of the cell 1. Lipids 2. Lipoprotiens 3. LPS lipopolysaccaride so much it can be called the LPS layer a. Lipid A b. Core polysaccharide c. O side chain (o Antigen) i. The O antigen is a pretty cool little guy because it is what is recognized by most immune systems. However, it can mutate like crazy and then once again, it is a new strain and the immune system can’t recognize it d. Importance of LPS i. Contributes to the negative charge of the surface. ii. Stabilizes the membrane 4. Braun’s Lipoproteins connect the outer membrane to the peptidoglycan 5. Porins only allows hydrophilic substances through a. Come in threes on the outer membrane 6. ii. Thick periplasmic space chopped full of proteins and is similar to a subway scene iii. Thin layer of peptidoglycan not as much which gives it the term gram negative (10% of the cell envelope) iv. Plasma membrane old glory v. vi. 2. Describe the effects of lysozyme and penicillin on a bacterial cell wall. To answer this question we need to know a thing or two about peptidoglycan i. Structure: 1. Made out of sugars called NAG and NAM a. Nacetylglucosamine NAG b. N acetylmuramic acid NAM 2. This is an alternating sugar backbone (NAG –Nam NagNam) 3. Now the cool part is that we can have amino acid chains that hang down ONLY from NAM periodically a. This will be a trick on the exam so watch out b. Also, an amino acid chain does not have to bind to everyone as well. 4. So now we have a mesh like structure kind of like a knight’s armor (the mesh metal looking stuff) 5. So you have a. NAG β1,4 glycosotic linkage NAM b. Hanging down or up from NAM, an amino acid chain that is about 4 amino acids long c. 6. Now let’s talk about the bonds between the hanging amino acids: a. Direct Peptide Bond b. Indirect interbridge chain of amino acids spanning the gap c. d. Now all of these factors make pep extremely resistant Now we can answer the question: i. Lysozymes These break down the bonds between the NAG and Nam sugar molecules β1,4 Glycositic linkages 1. This will cause the peptidoglycan to degrade and thus decreases its ability to prevent the cell from lysis ii. Penicillin penicillin works great for a process called transpeptidation the building of new peptidoglycan 1. Penicillin targets the peptide bonds between the amino acids and breaks them apart. Thus the amino acids can’t stick together to form a mesh like structure. 2. When transpeptidation occurs the bacterial cell punches holes in its peptidoglycan and then is quickly replaced by a new piece of peptidoglycan 3. However, if the peptidoglycan can’t bind because the bonds are destroyed, then there will be hole in the cell wall which is really bad for the cell 4. Ultimately it ends in lysis Characteristic Gram Positive Gram Negative What color Purple Pink they stain Pep 90% 10% (peptidoglyca n) (%) Outer most Pep Outer membrane layer Proteins Techoic Acids Lipoprotiens involved Lipotechoic Acids LPS Lipid A Core polysaccharide Oside chain (antigen) Cellular structure 3. Explain how bacteria may survive without a cell wall. Survival in isotonic environments (example) i. Shreoplasts ii. Protoplasts Mycoplasma i. No cell wall ii. Plasma membrane is more resistant to pressure 4. Describe capsules and slime layers and discuss their functions. Capsules i. Compose of polysaccharides ii. Well organized and not easily removed iii. Protection for desiccation and phagocytosis iv. Slime Layers similar to capsule except diffuse and easily removed and may play a part 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: These are like the supervisors of the bacteria where they serve a role in division, protein localization, and shape i. FTsZ cell division lots of them line up along the center of the molecule by finding the MerB scaffolding protein ii. MerB Line up along the center of the chromosome during cell division. iii. MinD prevents polymerization at the poles of the bacteria 6. Describe flagella structure and movement. Gramnegative Filament Flagellin type of protein, the actual whip part Hook the little curve in the flagellum Basal Body o Includes Pring Periplasam ring MSRing Membrane (plasma) ring Cring cytoplasm ring MotorSits between the MS and C ring Motor o L+P ring do not rotate/ MS+ C ring o MOT protein surround MS ring and Cring o Fliprotiens commander of the flagellum sit in the MS and Crings o MEMORIZE THIS STRUCTURE BELOW AND KNOW IT VERY VERY WELL o GramPositive Only 2 Rings o Because of the diffrences in the cellular envelope Shown below on the right Flagellum Characteristics How they are Built: o So, it looks like a channel that leads from the cytoplasm to the top of the growing flagellum (Assembly line) o They are channeling up flagellin molecules o CAP proteins stand at the top and direct the flagellin to grow in a circular direction o Imagine you are unscrewing the bolt from the back of your calculator with a screwdriver, as the screw comes out, you notice it looks like it is growing by spinning. This is what the CAP protein does to grow the flagellin. o It just spins in a circle from one point and puts the proteins down in a circular fashion. o How they move: o Gram Negative (Similar to gram positive except a minus a few rings) 2 –part motor that produces torque Rotor This is when the C ring and the MS ring spin and interact with the stator StatorMot A and B proteins Imagine a revolving door, where at the very center and top of the door you hook a flagellum. When you push (H ) on the door (Cring and MS ring) you will rotate the stable column (L and P ring) that holds the flagellum The proton motive force (PMF) (i.e you pushing the door) is the real star of the show. This works by shuttling H across the membrane between the MOT A protein and the MS and C rings Takes 1000 protons to turn 360 degrees (Monotrichous polar Flagellum (fastest)) How they make the Cell move: o Rotates counter clockwise causes run o Rotates clockwise tumble o Up to 1100 rev/sec o So the way to think about it, bacteria with flagellum don’t have a steering mechanism to direct their movement (inefficient) o So, when their flagellum rotate, they can only go in one general direction, then once they have past their target they have to tumble to change directions o o Peritrichous motility bundled flagella that looks like a spinning ponytail o Spirochete motility Multiple flagellum form an axial fibril and wraps around the cell So, they remain in the periplasmic space (remember they are gram negative so the periplasmic space is bigger). And BOOM they turn into an instant drill bit!!! So their movement is similar to that of a wiggling drill bit: spinning and flexing. 7. Define chemotaxis and describe how bacteria move toward an attractant (or away from a repellent). i. Movement toward a chemical attractant or a way from chemical repellent ii. Concentrations of chemo attractants and chemo repellents detected by the chemoreceptors on the cells iii. Complex but very rapid 1. Response= 20miliseconds 2. 2 +60 cell lengths per second iv. Positive and Negative 1. Bacteria are all or nothing type of folks 2. They will go after something 100 % if they detect it and want it. 3. Or they will try not to go near it in the other case 4. Therefore: a. Want it= increase the run= decrease the tumble b. Don’t want it= decrease the run= increase the tumble c. 8. Describe other types of motility (spirochete, twitching, and gliding). i. Twitching This goes on with the ends of the cell, involves short jerky motions ii. You know those sticky hands that you would get at like chucky cheese that you could throw out and stick to stuff? (Like these) 1. 2. Well, same concept, in twitching, the pili at the ends of the cell, send out their stick hands (polysaccharide) and stick them to the surface of another cell or the ground. Then they haul them in which causes the cell to move (discontinuous = twitching) iii. Gliding 1. NO PILUS! We think little baby feet move the bacteria. 2. A lot of slime production 3. Gliding motion 9. Understand the structure and functions of bacterial endospores, the basics of sporulation and germination, and endospore resistance. Complex dormant structures formed by the bacteria typically due to the lack of nutrients in the surrounding environment Can come back to life (germination) Typically occurs in gram positive cells Resistant to i. Heat ii. Radiation iii. Chemicals iv. Desiccation (Water loss) Where the endospore is made: i. Central center of the cell ii. Sub terminal Kind of close to the end bit not all the way iii. TerminalRight on the edge of the cell iv. Swollen sporangiumOMG THE CELL IS A LOLLY POP v. Structure of an Endospore i. ii. Goes Like This: 1. Exosporangium 2. Coat 3. Outer Membrane 4. Cortexmade out of pep and less linked than the cell wall 5. Germ cell wall 6. inner membrane 7. Core 8. ECOCGIC 9. Every Coat On Corn Glows In Cereal What makes the endospore so rock solid? i. Core low water content 1. Calcium dipicolinate (CaDPA) 2. SASP ssmall, acid soluble , DNA – binding proteins a. They are doublestranded DNAbinding proteins that cause DNA to change to an Alike conformation. They protect the DNA backbone from chemical and enzymatic cleavage and are thus involved in dormant spore's high resistance to UV light (radiation). SASP are degraded in the first minutes of spore germination and provide amino acids for both new protein synthesis and metabolism (https://www.ebi.ac.uk/interpro/entry/IPR001448) 3. Lower the pH as well ii. But the real stars of the show are the Exosporangium and Spore Coat 1. Supreme armor Ok, cool so it can stand up to some stuff but what makes it so great? i. The fact that it is an escape pod for the cell that is virtually invincible means that the bacteria can keep on going and doing their thing no matter what ii. Germination and Sporulation 1. 3 Steps: a. Activation: i. Prepares spores for germination ii. Often results from treatments like heating b. Germination: i. The nutrients it needs are detected ii. Spore swelling and rupture of the coat iii. Loss of resistance but…Increased metabolic activity c. Outgrowth: i. BOOM vegetative cell shows up from the germination process Chapters 11.1, 10.1 – 10.4 10. Know the requirements for microbial survival and growth and their sources. Source of energy i. Cellular work Source of electrons i. Role in energy production ii. Reduce CO2 to form organic molecules Nutrients i. Carbon and hydrogen and oxygen ii. Synthesize building blocks for cell to be maintained and grow Let’s break down energy and electrons i. Sources 1. Organic and inorganic compounds 2. Energy is obtained through Oxidation of a compound or Sunlight (energy only) ii. Energy is usually reserved in the cell and is used as a currency: ATP iii. Easy to break easy to make iv. 11. Define and recognize the major nutritional types of microorganisms based on their energy source, electron source, and carbon source. i. Different places where organisms get there energy: 1. Phototrophs: use the sun 2. Chemotrophs: obtain energy from the oxidation of compounds ii. Different places where organisms get their electrons 1. Lithotrophs use reduced inorganic substances 2. Organotrophs obtain electrons from organic compounds iii. Different places where organisms get their Carbon 1. Heterotroph use of organic molecules as carbon sources (which often serve as energy and as an electron source) 2. Autotroph use carbon dioxide as their sole or principal carbon source 3. Must obtain and energy and other electrons from other sources 4. Primary producers iv. Why all the names? 1. SAMPLE EXAM QUESTION 2. Given these three characteristics, classify this organism 3. Uses the sun as energy, digests a lot of organic compounds and make frequent use of carbon dioxide 4. Answer: PHOTOLITHOAUTOTROPH a. Photo energy source b. Litho electron source c. Autotroph carbon source 12. Define metabolism, catabolism, and anabolism. Metabolism includes all of processes involved with energy exchange Anabolism is the set of metabolic pathways that construct molecules from smaller units. Catabolism is the set of metabolic pathways that breaks down molecules into smaller units that are either oxidized to release energy, or used in other anabolic reactions. Metabolism Catabolism Anabolism Fueling Reactions Synthesis of complex organic molecules (glucose) from simpler ones (ATP) Energy conserving reaction Requires energy and building blocks from fueling reactions Provide reducing power electrons Generates precursors for biosynthesis ON CONSTANT CYCLE BETWEEN THE TWO 13. Understand the concepts of free energy (G) and standard free energy change ( G ). G (Gibbs free energy) the amount of free energy available to do work. Δ G Change of free energy after reaction is ran to completion o How much energy was used or released o Free Energy Change Characteristic Exergonic Endergonic Energy is Released Used/ Consumed o ( G ). Negative Positive Spontaneous? Yes No Simple A+B A+B+Energy Reaction C+D+energy C+D 14. Explain the importance of ATP. Energy Currency of the cell ATP Adenosine Triphosphate The phosphoanhydride bonds that attach the last two triphosphates to the bon are high in potential energy because they are easy to make and easy to break If you break 1 bond you will release 31 kJ/mol If you break 2 bonds you will release 46 kJ/mol i. Why the negative? Because this reaction is spontaneous and is releasing energy ii. Why is it 46 for the next one and not 62? Because as you get closer to the sugar, the bond becomes more difficult to break and thus causing a net energy gain of 46 kJ/mol. iii. Role of ATP in Metabolism i. The role is to make non spontaneous reactions spontaneous because the cell has too. ii. The big picture with ATP i. Like the economy, money is cycled around and around to make the world run. ii. In cells, the ATP is cycled around and around to make the cell run. iii. SO… to make money, (ADP ATP) you have to have an asset (Aerobic Respiration, Anaerobic Respiration, Fermentation, Phototrophy, and Chemolithotrophy) iv. SO… to get stuff you need (chick fila! Or more prevalent chemical or transport work) you need to spend money (ATP) v. vi. However, the cell must be efficient with its time because it needs a certain amount of ATP to survive and if it does not make it in time the cell will die 1. CELLS ONLY USE REACTIONS THAT RELEASE GREATER THAN 30 kJ/mols 2. Such as the ones give below a. 3. Know this chart!!!! 15. Understand redox reactions including the standard reduction potential 0E ) of half o reactions, the electron tower, and their relationship to G . Oxidation Reduction Reactions o Many metabolic processes involve electron transfers o Carriers are used to transfer electrons from electron donors (oxidizing agent) to electron acceptor (reducing agent) o Often results in things being restored (NAD NADH) o OIL RIG Oxidation involves loss Reduction involves gain Electron Donating Half Reaction o o Electron accepting half reaction o o Therefore: o o Half Reactions are always written as reduction reactions H 2reaction is the best electron Donor O 2is the best electron acceptor Standard Reduction Potential (E’O) o Equilibrium constant for an oxidation reduction reaction o Measure of the reduction agent to lose electrons More NEGATIVE E’O= better electron donor More POSITIVE E’O = better electron acceptor o Electron tower 2 H/ H 2 ½ O /2H 2 The greater the difference in E’O between the donor and the acceptor the more negative Δ G= more spontaneous When you receive an electron tower problem, always arrange it from negative to positive (Negative at the top and Positive at the bottom) Sample Question C4H4O4/C4H6O4 +0.31 V 2H / H 20.5 V Between these two reactions what reactant or product will be the electron donator? (H 2 Between these two reactions, what will be the electron acceptor? (C4H4O4) TO SOLVE THESE PROBLEMS WITH NO SWEAT: 1. Arrange the reactions with the most negative on top of the other 2. The top right product of the two will be electron donor and the bottom left product will be the electron acceptor As you go down the tower you will release energy As you increase the number of carriers = increase energy released During photosynthesis light drives the electrons up the tower The relationship between Δ G ’ and E´0 i. The greater the difference between the E´0 of the molecules involved (or the further the electrons go down the electron oower), the more energy that will be released (the more negative the Δ G ’ will be for this redox reaction). 16. Describe the location, organization, and functions of the Electron Transport Chains in bacteria. ETC In prokaryotes: plasma membrane In Eukaryotes: Christa of the mitochondrion This is a chain of mini electron towers 1. The first tower has a negative E’O 2. The first carrier is reduced and the electrons are transferred to the next carrier 3. Since the first tower is spontaneous, the energy is used to phosphorylate ATP 4. The net energy change of the complete reaction is calculated by the difference of reduction potentials of the primary and final acceptor 5. Increase nutrition= increase the goodness of the carriers ii. Electron Carriers 1. 2 Classes a. Coenzymes freely diffusible; can transfer electrons from one place to another in a cell (NAD) i. Nannies on the move taking care of the electrons b. Prosthetic Groups fixed to the enzymes in the plasma membrane that function in membrane associated electron transport reactions (cytochromes) iii. Oxidative phosphorylation 1. Used in respiration a. ATP is made by a proton motive force (ATP synthase) b. 2. Photophosphorylation a. Used by phototrophic organisms b. Light drives the redox reactions that generate the proton motive force c. iv. Respiration 1. Involves the use of an ETC 2. As electrons pass through the electron transport chain to the final electron acceptor, a proton motive force (PMF) is generated and used to synthesize ATP 3. 2 types a. Aerobic respiration i. Final electron acceptor is oxygen b. Anaerobic respiration i. Final electron acceptor is an exogenous acceptor: ii. NO3, SO42, CO2, Fe3+, or SeO42 4. Oxidative phosphorylation this is the primary producer of ATP 17. Define the two classes of electron carriers. i. Coenzymes freely diffusible; can transfer electrons from one place to another in a cell (NAD) 1. Nannies on the move taking care of the electrons ii. Prosthetic Groups fixed to the enzymes in the plasma membrane that function in membrane associated electron transport reactions (cytochromes) + + 18. Describe how NAD /NADH and NADP /NADPH carry electrons and their roles in metabolism. i. The star of the electron carriers: NAD 1. NAD nicotinamide adenine dinucleotide + 2. NADP nicotinamide adenine dinucleotide phosphate 3. NADH and NADPH good election donors and have a reduction potential of 0.32 V NOT A PART OF THE ETC!!!! ONLY BRINGS ELECTONS!!!! 4. Coenzyme 5. Freely diffusible freely moving a. Carries 2 e and 1H (the 1 H that is released) 6. NADP / NADPH works the same way except is involved in anabolism a. Chapter 11.2 – 11.8 19. Compare and contrast aerobic respiration, anaerobic respiration, and fermentation in bacteria. Characteristic Aerobic Anaerobic Fermentatio n Final Electron Oxygen Any other Pyruvate Acceptor (Exogenous electron (Endogenous ) acceptors ) other than oxygen (Exogenous ) Max yield ATP 32 ATP 2 ATP 2 ATP ETC? Yes Yes No Type of Substrate Substrate Substrate phosphorylati Level and level level on Oxidative 20. Compare and contrast substratelevel phosphorylation and oxidative phosphorylation. Substrate level phosphorylation synthesis of ATP by reactions in which ADP is one of several substrates and ATP is one of several products of an enzyme catalyzed reaction. i. This is like the physical addition of a phosphate by an enzyme. ii. Like ADP ATP by way of an enzyme Oxidative Phosphorylation metabolic pathway in which the mitochondria in cells use their structure, enzymes, and energy released by the oxidation of nutrients to reform ATP. This is using the reactants of other products to phosphorylate ATP (ETC) 21. Describe aerobic catabolism (overview). process that completely catabolizes an energy source to CO2 using o Glycotic pathway o TCA cycle (Kreb’s Cycle) o ETC with O as2the final e acceptor Produces ATP and recycles electron carriers Production: o Max total yield of 32 ATP (If all goes well) 4 ATP from the oxidation of glucose (substrate level phosphorylation) 28 ATP from NADH and FADH being oxidized in the ETC (Oxidative phosphorylation) 22. Describe the organization and functions of the electron transport chain in aerobic respiration including its role in ATP production. As described before, the ETC uses the electron carriers NADH and FADH2 to operate enzymes that can shuttle protons across the membrane thus creating a PMF. This PMF is vital in the use of ATP synthase. This PMF established by the ETC is what turns the motor this phosphorylating ADPATP The term aerobic respiration is coined because at the end of the ETC there has to be an electron dump. This is oxygen This also unique because the Oxygen is the best electron acceptor (most positive E’0 value). 23. Understand the Chemiosmotic Hypothesis. The chemiosmotic hypothesis suggests that the action of ATP synthase is coupled with that of a proton gradient. It is the action of the proton gradient that causes a proton motive force that allows ATP synthase to phosphorylate ADP and inorganic phosphate to ATP. (https://teaching.ncl.ac.uk/bms/wiki/index.php/Chemiosmotic_hypothesis) 24. Explain the function of ATP synthase. ATP synthase is the smallest molecular motor known. This motor is driven by the PMF established by the ETC It phosphorylates ADPATP by changing the conformation of its subunits. 25. For aerobic respiration, explain where in the pathway ATP is produced (glycolysis, TCA cycle, and ETC), the methods of ATP production used for each ATP generated, the electron carriers used, and the number of ATPs produced (during the process and the final net yield). 26. Summarize the major features of the EntnerDoudoroff pathway. Used by some soil bacteria Yield pyruvate and glyceraldehyde 3P THE KEY DIFFRENCE IS THE PRODUCT: 2keto3deoxy6 phosphogluconate KDPG i. So if you see this product get excited cause you got some points nd Product (when coupled with 2 half of EmbdenMeyerhof) i. 1 ATP ii. 1NADH iii. 1 NADPH iv. 27. Describe the process of fermentation, its functions, and its products. Takes the place of the absence of the exogenous electron acceptor i. O not needed Uses pyruvate endogenous (made inside the cell) Reduces pyruvate “Electron Dump” Recycles electron carriers (notice a theme?) (this is why they ferment) Forms only 2 ATP Via substrate level phosphorylation 28. Produces fermentation products i. Classes 1. Ethanol bread, wine and beer 2. Lactic Acid a. Homolactic cheeses, sour cream b. Heterolactic pickles, buttermilk and spoilage of food 3. Mixed Acid 2.3 Butanediol 4. Propionic acid 29. Distinguish between mixed acid and butanediol fermentation. Mixed Acid i. test detects pH < 5 ii. During fermentation, several products can be produced. iii. A lot of them are acids and thus will drop the pH below 5 Butanediol is an acid as well however, it has a key intermediate known as acetoin 30. Explain the purpose of the MRVP test and know how it works. Methyl Red i. Purpose: To test for the acids lactic, acetic, succinic, and formic acid (mixed acid) ii. Positive Reaction: You have a red tube , like a little bit of red at the top of the tube iii. Media/ reagents: MRVP iv. How the media and the reagents work together: (MRVP stands for the methyl red test and the voges proskauer test. So when the methyl red a pH indicator is added to the solution, it turns red indicting the presence of an acid. v. What you have: You have a mixedacid fermenter which is a great way to distinguish some of the bacterium. Vouges Proskauer i. Purpose: Instead of a mixed acid fermenter you have a Butanediol fermenter. This is how you tell 1. Positive Reaction: Burnt red tube all the way through ii. Media/ reagents: MRVP and Barritts reagent A and Baritts reagent B. iii. How the media and the reagents work together: So for the reaction to work, Butanediol needs to be converted to acetoin and can be accomplished by shaking the tube with the reagents in it. Then over the course of 30 min at room temperature the solution changes to burnt red Chapter 7.1, 7.3 – 7.4, 7.6 – 7.7 35. Describe the growth of bacterial cells (binary fission). a. Growth increase the number of cells i. Usually study population growth rather than microbial growth ii. Binary Fission (two cells from one) b. Cell elongation, cellular stuff increases proportionally i. DNA is replicated and it is segregated ii. One cell two cell= one generation 36. Describe in detail the four phases of bacterial growth observed in a batch culture. a. Growth curve i. Observed in a batch culture 1. One place, One medium, One vessel, No addition of food, 2. Plotted as log of cell versus time ii. 4 Phases 1. Lag first starting out, the bacteria freaks out cause it might be different a. So if you take your bacteria out of one medium and put it another medium, then the bacteria must first orient itself before it can grow exponentially b. The more difference the new medium is the longer the lag phase will be 2. Log This is the exponential growth phase a. Exponential b. Maximal c. Constant d. Uniform and the healthiest cells 3. Stationary: when the cell number remains constant overtime a. Stop reproduction b. Death rate= reproductive rate c. Reasons i. Nutrient limitation ii. Limit oxygen iii. Toxic waste and cell accumulation iv. Critical population density d. Starvation responses: i. Morphological changes 1. Endospore formation 2. Decrease in size ii. Special starvation proteins 1. Increases crosslinks in the cell wall 2. DPS protein protects DNA 3. Chaperon protein prevents protein damage e. Increases the length of this phase f. Persister cells i. Harder to kill ii. Increase the virulence of the bacteria 4. Death Phase a. Lysis b. Cant reproduce iii. Can be useful for absorbance and quantification b. 37. Be able to label a growth curve. a. 38. Define generation time, and be able to calculate it. a. Generation time time needed to double in size (Doubling time) b. Varies depends on the species and environment c. Exponential growth cell number doubles with in a fixed time period (slope of the line) d. Number of bacteria = 2 n = number of generations e. Calculating number of generation between two populations: N 0 i. log N −log¿ t n=3.3¿ f. N =specificnumber of bacteriaduringthelog phase t g. N 0intial populaiton i. You don’t have to know how to derive it. ii. Just memorize this 39. Calculating generation time: a. Example: i. Nt=1.0 x 10 8 7 ii. No= 5.0 x10 N 0 b. log Nt−log¿ n=3.3¿ c. Therefore: 7 5.0x10 log1.0x10 −log¿ n=3.3¿ n=1−→only1generation Generation time =t/n2/1=2 hours/ generation=0.5 generations/ hour Growth constant: k= 0.5 generations/ hour 40. Explain the methods of measuring the growth (number) of microbes (microscopic count, plating methods, and turbidity measurements). a. Direct i. Total cell counts – physical counting ii. Counting chamber iii. Electron counter problem is that you may count dead cells b. Viable Cell counts counts the number of CFU’s i. Plating techniqueGives underestimate ii. Membrane filter c. Indirect i. Dry weight ii. Turbidity Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. d. Spectrophotometer i. 540600 nm optimum absorbance for bacteria ii. Gives an over estimate because it counts the dead cells too. 41. Describe how water activity, pH, temperature, and oxygen affect microbial growth. a. Water activity amount of water in the environment that is available to the organism i. 01 = pure water = 1 ii. Any type of solutes is unavailable to micro iii. Increase the solute concentration= lower the water availability iv. Adaptation 1. In Hypotonic solutions, bacteria use mechanosensetive channels in membrane to allow solutes out which changes the osmotic surroundings which will cause water to go out of the cell by osmosis 2. SOLUTES LEAVE FIRST THAT PULL WATER OUT 3. Hypertonic solutions a. Increase interval solute concentration with competitive solutes b. More water comes into the cell c. This explains why salt water is good for wounds, because the bacteria in the wound unless they are halophiles or Extreme halophile, they will undergo plasmolysis b. pH This is always a factor as that every organism has an optimal pH range at which the organism can remain. c. Oxygen is the key component in respiration which creates the most ATP. If this component is taken away, then the ATP yield would drop significantly and thus cause the rate of growth of bacteria to drop. 42. Be able to name, recognize, and define the types of microorganisms that grow in various environments, and know the adaptations they have made to live there. i. Nonhalophile= can survive in little to no salt ii. Halophile can survive in little to a lot of salt iii. Extreme halophile can survive in a lot to a crap ton of salt. iv. Obligate aerobes Can only grow in oxygen and nothing else v. Microaerophiles only want 210 % oxygen, lower oxygen is necessary for their metabolism vi. Facultative aerobes (anaerobes) flexible and able to grow in either vii. areotolerant anaerobes only fermentation with these guys obligate fermenters viii. Obligate anaerobes NO OXYGEN! ix. Neutrophile bacteria grow in neutral environments x. Acidophile bacteria grow in acidic environments xi. Alkaliphile bacteria grow in basic environments 43. Explain how microorganisms protect themselves from the toxic products of oxygen reduction. a. The enzyme, catalase, is produced by bacteria that respire using oxygen, and protects them from the toxic byproducts of oxygen metabolism 44. Describe biofilms including their characteristics, growth (formation), advantages (for bacteria), and disadvantages (for humans). a. Growth i. Freeswimming bacterial cells land on a surface, arrange themselves in clusters, and attach. ii. The cells begin producing a gooey matrix. iii. The cells signal one another to multiply and form a micro colony. iv. The micro colony promotes the coexistence of diverse bacterial species and metabolic states. v. Some cells return to their freeliving form and escape, perhaps to form new biofilms. vi. http://www.colgateprofessional.com/patient education/articles/whatisbiofilm b. Characteristics i. The plaque that forms on your teeth and causes tooth decay and periodontal disease is a type of biofilm. Clogged drains also are caused by biofilm, and you may have encountered biofilmcoated rocks when walking into a river or stream. c. Advantages for bacteria: i. They have the ability to grow in unfavorable conditions which means that they have several adaptations for nutrient scavenging. ii. When they grow as a colony they are much harder to eradicate iii. Faulty cleaning techniques as well as bad cleaning chemicals induce this change. d. Disadvantages for humans: i. They are hard to get rid of a can grow anywhere. This means that they are potentially dangerous for humans DISEASES* Strep Throat (Streptococcal pharyngitis) a. group A betahemolytic streptococcus b. Gram Positive, cocci beta hemolytic c. Transmitted via saliva or shared liquids d. SORE THROAT. The back of the throat will be swollen and red and the tonsils enlarged, and there may be swelling and tenderness in other parts of the neck and throat. Other symptoms include fever, chills, malaise, muscle pain and headache. http://ecdc.europa.eu/en/healthtopics/streptococcal_pharyngitis/pages/i ndex.aspx#sthash.H36PgJnS.dpuf Cholera e. Vibrio cholerea. f. Gram negative, comma shaped g. Spread mostly by water and food that has been contaminated with human feces containing the bacteria. Insufficiently cooked seafood is a common source. Humans are the only animal affected. h. Classic symptom is large amounts of watery diarrhea that lasts a few days. Vomiting and muscle cramps may also occur... Bacterial Meningitis (Meningococcal) i. N. meningitides j. Gram negative, diplococcus because of its tendency to form pairs k. respiratory and throat secretions l. Nausea, m. Vomiting, n. Increased sensitivity to light (photophobia), and o. Altered mental status (confusion). Lyme Disease p. Borrelia burgdorferi q. Spirochete class of the genus Borrelia. Can be either gram positive or gram negative r. Spread through the bite of infected ticks. s. Fever, chills, headache, fatigue, muscle and joint aches, and swollen lymph nodes t. Severe headaches and neck stiffness Infectious Mononucleosis u. EpsteinBarr virus (EBV v. Virus w. Saliva transmission x. Pain circumstances: can occur while swallowing y. Whole body: fatigue, fever, chills, malaise, or body ache z. Also common: sore throat, swollen lymph nodes, swollen tonsils, headache, or nausea Gas Gangrene (Clostridial Myonecrosis) a. C. perfringens aa. Grampositive, rodshaped, anaerobic, sporeforming pathogenic bacterium of the genus Clostridium ab. Site of trauma or a recent surgical wound. In some cases, it occurs without an irritating event. Persons most at risk of gas gangrene usually have blood vessel disease (atherosclerosis, or hardening of the arteries), diabetes, or colon cancer. ac. Symptoms i. Air under the skin (subcutaneous emphysema) ii. Blisters filled with brownred fluid iii. Drainage from the tissues, foulsmelling brownred or bloody fluid (serosanguineous discharge) iv. Increased heart rate (tachycardia) v. Moderate to high fever vi. Moderate to severe pain around a skin injury vii. Pale skin color, later becoming dusky and changing to dark red or purple viii. Swelling that worsens around a skin injury ix. Sweating x. Vesicle formation, combining into large blisters xi. Yellow color to the skin (jaundice)
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