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Finished Study Guide for Exam 2

by: Katie Kessler

Finished Study Guide for Exam 2 81382 - MICR 3050 - 001

Katie Kessler
GPA 3.7
General Microbiology
Krista Barrier Rudolph

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Dr. Rudolph finished they notes in class so if you haven't gotten a study guide, this one is complete! Even if you purchased the one I put up on Saturday all I did was added the notes from the powe...
General Microbiology
Krista Barrier Rudolph
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This 23 page Study Guide was uploaded by Katie Kessler on Monday October 5, 2015. The Study Guide belongs to 81382 - MICR 3050 - 001 at Clemson University taught by Krista Barrier Rudolph in Fall 2015. Since its upload, it has received 66 views. For similar materials see General Microbiology in Biological Sciences at Clemson University.


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Date Created: 10/05/15
UNIT 2 STUDY GUIDE Fall 2015 MICR 3050 OBJECTIVES Chapter 31 35 1 Describe the structure and functions of lipopolysaccharide LPS The structure of LPD consists of Lipid A core polysaccharides and an 0 side chain 0 antigen Lipid A is embedded in the outer membrane while the core polysaccharide and 0 side chain extend out from the cell The importance of LPS consists of the negative charge on the cell surface and Lipid A helps stabilize the outer membrane LPS creates a permeability barrier which keeps out toxins and keeps the consistent negative charge In addition LPS may mutate to protect from host defenses LPS can also act as an endotoxin Lipid A which means it can be poison when it needs to be Explain how bacteria may survive Without a cell wall Bacteria can survive without a cell wall in isotonic environments Protoplast remove gram positive membrane and spheroplasts remove the gram negative membrane Mycoplasmas are an example of a bacteria that can cause diseases without a cell wall They have a PM that is more resistant to osmotic pressure Describe capsules and slime layers and discuss their functions Capsules are usually composed of polysaccharides and are very organized making it uneasy to remove from the cell Protective features of capsules include being resistant to phagocytosis desiccation drinks the water or eats to survive and they can exclude viruses and detergents In addition to these advantages the polysaccharide is sticky which makes a great biofilm Slime molds are similar to capsules except they diffuse and are unorganized which means that they are easy to remove Slime molds often aid in motility and secretion It is important to note that phagocytosis doesn t work in slime molds Chapter 36 39 4 Describe the following bacterial structures and their functions Cytoskeletal It forms a framework for the movement of organelles around the cytoplasm It includes protein microfilaments intermediate filaments and microtubules Proteins Proteins are large complex molecules that play many critical roles in the body They do most of the work in cells and are required for the structure function and regulation of the body s tissues and organs Cell inclusions stored nutrients secretory products and pigment granules Examples of storing energy like carbon you can store PHBglycogen for phosphate you can store polyphosphate granules and for sulfur you can store granules that assist in metabolism Lastly for Nitrogen storage you can use cyanophycin granules that store AA Other additional inclusions to be aware of are gas vacuoles that provide buoyancy and magnetsosomes which are used to magnetite particles for orientation in earths magnetic field They are also known as aggregates of organic or inorganic material granules crystals globules Some inclusions are enclosed by a single layer of membrane or invaginations of the PM however it is important to note that it is not an organelle bc they do not have a real function Flagella locomotion that often has function as a sensory organelle being sensitive to chemicals and temperatures outside the cell Endospores The primary function of most endospores is to ensure the survival of a bacterium through periods of environmental stress Describe agellar structure and movement Flagella is a threadlike appendages extending outward from PM and cell wall Its functions include motility and a swarming behavior It attaches to surfaces which helps it to swim and helps it burrow It also has the ability to evade or cause disease Flagella can be monotrichous one agellum polar agellum agellum at the end of the cell amphitrichous one agellum at each end of the cell Iophotrichous cluster of agella at the end or both ends and lastly peritrichous spread over entire surface of the cell The structure of agella consists of a tail which is the lament and it is made out of the protein The hook attaches the lament to the basal body and the basal body is the motor the 2 part motor produces torque which consists of the rotorC ring and MS ring and the statorMot A and Mot B proteins There are 4 layers of the agella L ring LPS and P ring peptidoglycan don t spin These hold the agellum in place The MS ring membrane supramembrane and the C ring cytoplasm spin The Mot proteins are stationary as well Cap proteins build the filaments The lament is built from the tip not the base bc it has to be in contact with the CAP proteins An important note to take in consideration is that the proton motive force spins the agellum The ETC is in the cell membrane and during respiration it shuttles H on the outside of the cell and negative cells are on the inside This is the proton motive force This then gives you an electrochemicalpH gradient energy Dr Rudolph explains this as a cell going through a revolving door and as the door spins the rings spin Define chemotaxis and describe how bacteria move toward an attractant or away from a repellent Chemotaxis is the movement of an organism in response to a chemical stimulus Positive chemotaxis toward motion has lowered frequency of tumbles and the runs are longer Negative chemotaxis away consists of more tumbling and less runs Flagellum rotates like a propeller and move in a CCW direction called a run and move in a CW direction when it tumbles Describe other types of motility spirochete twitching and gliding Spirochete motility form an axil fibril that winds around the cell not on the outside of the cell it is on the inside and the agella remains in the periplasmic space inside the outer sheath while it moves in a corkscrew shape which exhibits exing and spinning movements This is advantageous bc it can infect tissues and burrow in them Twitching motility the pili is at the ends of the cell and is short intermittent and involves jerky motions The cells are in contact with each other and the surface Gliding motility smooth movements that can occur with single cells or in a group of cells Some cells produce slime that help it move across a solid surface 8 Understand the structure and functions of bacterial endospores the basics of sporulation and germination and endospore resistance Bacterial endospore complex and dormant structure that is formed by some bacteria Endospores are located in various places bc they are resistant to numerous environmental conditions such as heat radiation chemicals and desiccation Just a fun fact about endospores all the bacteria that make spores are gram positive Bacterial endospore structure Endospores are resistant bc of their numerous layers which consist of an exosporium thin layer on the outside Coat 50 layers of proteins that are impermeable to toxins in the environment The outer membrane lipid bilayer Cortex peptidoglycan less cross linked than the normal cell this is advantageous for the protection of the spore Core cytoplasm Endospore resistance The core is low in water contents which means that it is a protective formant layer that doesn t have much metabolic activity and enzymes don t work in this layer The calcium dipicolinate stabilizes the DNA SASPs saturate the DNA and are small acidsoluble DNA binding proteins The core has a slightly lower pH 7 and this disables the enxymes from working properly Sporulation making the spores when the cell stops dividing The process DNA becomes denser and the endospore septum grows AROUND the protoplast then dehydration occurs and the exposporium and coat layers form Germination is triggered by food heat water The spore starts swelling and ruptures the spore coat which allows the water to come in There is an increase in metabolic activity There is an emergence of a vegetative cell Chapters 111 101 104 9 10 11 Know the requirements for microbial survival and growth and their sources Energy is important for cellular work repairmaintenancegrowthdivision Electrons play an important role in energy production and reduce C02 to form organic molecules like methane The important nutrients include carbon hydrogen and oxygen which aid in synthesizing organic building blocks needed for cell maintenance and growth The sources include inorganic and organic chemical compounds that are obtained by oxidizing a compound and sunlight gives energy Define and recognize the major nutritional types of microorganisms based on their energy source electron source and carbon source Energy source phototrophs light and chemotrophs obtain energy from oxidation of chemical compounds Electron source lithotrophs inorganic substances and organotroph organic substances Carbon source Heterotrophs organic molecules are used as carbon sources that serve for energy and electron sources and autotrophs use carbon dioxide as their sole principle carbon source and are known as primary producers Define metabolism catabolism and anabolism Metabolism total of all chemical reactions occurring in the cell Catabolism fuels reactions energy conserving reactions and provide ready source or reducing power from electrons generates precursors for biosynthesis 12 13 14 15 16 Anabolismthe synthesis of complex organic molecules from simpler ones requires energy and building blocks from fueling reactions Understand the concepts of free energy G and standard free energy change A G quot Free energy the amount of energy that is available to do useful work Delta Gthe change in energy that can occur in chemical reactions Chemical work transport and mechanical work is carried out by microorganisms AG standard free energy change at pH 7 temperature of 25 degrees Celcius 1 atmosphere reactants and products at 1 M concentration Distinguish between exergonic and endergonic chemical reactions and their relationship to A GO39 Exergonic releases energy the reaction proceeds spontaneously and the delta G prime is negative Endergonic requires energy the reaction will not proceed spontaneously and delta G prime is positive Explain the importance of ATP Energy is often released in the form of protium or H moving down an electrochemical gradient ATP synthase consists of 2 regions the F0 portion is within the membrane and the F1 portion of the ATP synthase is above the membrane inside the matrix of the mitochondria E coli ATP synthase is the simplest known form of ATP synthase with 8 different subunit types Be aware of other highenergy compounds and know the change in standard free energy requirement for cells to use them Cells use energy rich compounds that give them a greater value of 30 kJmol for example phosphophenolpyruvate acetyl phosphate acetyl CoA and 13 Biphosphoglycerate Lower energy rich compounds will include glucose6 phospate and AMP Understand redox reactions including the standard reduction potential Eo39 of half reactions the electron tower and their relationship to A GO39 Redox reactions are reactions in which one species is reduced and another is oxidized Therefore the oxidation state of the species involved must change These reactions are important for a number of applications including energy storage devices batteries photographic processing and energy production and utilization in living systems including humans Reduction A process in which an atom gains an electron and therefore decreases or reduces its oxidation number Basically the positive character of the species is reduced Oxidation A process in which an atom loses an electron and therefore increases its oxidation number In other words the positive character of the species is increased OIL RIG Oxidation is LOST Reduction is GAIN 3 w 21 Allis11 a ear 151mi all For example Als is being oxidized Ag aq is being reduced oxidation and reductions involve the transfer of not just e but both e and proton H Standard Electron Potential E o equilibrium constant for an oxidativereduction reaction It is the measure of the tendency of the reducing agent to LOSE electrons The more negativebetter e donor and the more positivebetter e acceptor Electron tower most negative is at the top and most positive is at the bottom Oxygen is the BEST known e receptor at the bottom of the tower The greater the diff bw the E o of the donor and E o of the acceptor the more negative free energy 17 Describe the location organization and functions of the Electron Transport Chains in bacteria Location mitochondria cristae Organization e carriers are organized into the ETC with the first e carrier having the MOST negative E o Functions transferring energy by making proton gradients 18 Define the two classes of electron carriers Coenzymes freely diffusible can transfer e from one place to another in the cell ex NAD freely moves around the cell Prosthetic groups firmly attached to an enzyme in the PM ex cytochrome cannot leave the chain 19 Describe how NADNADH and NADPNADPH carry electrons and their roles in metabolism NADH and NADHP good e donors bc electron reduction potential 032 NAD and NADH coenzymes bc they carry 2e plus 1 Halso involved in catabolism NADHP and NADP anabolism works the same way as NAD and NADH though Chapter 112 118 20 Compare and contrast aerobic respiration anaerobic respiration and fermentation in bacteria 39 I l39 I 39ll39l39 I Aerobic Respiration Anaembic Respiration Fermentation Oxygentequired Yes No No Type of phosphorylatlon Substrate39level and oxidative Substratelevel and oxidative Substratelevel Final electionhydtogen Oxygen N0 802 or012 Organic molecules acceptm Potential molecules of 3638 236 2 ATPproduced Copwghm 2008 Pom Education Inc pubishing as Benjam39n Cummings 21 22 23 24 25 Compare and contrast substratelevel phosphorylation and oxidative phosphorylation Substrate level phosphorylation used in fermentation and other pathways ATP is synthesized through catabolism Oxidative phosphorylation used in respirationATP is produced by a proton motive force As E pass through the ETC a PMF is generated and used to synthesize ATP Describe aerobic catabolism overview Final acceptor oxygen Aerobic respiration involves three major processes glycolysis the Kreb39s tricarboxylic acid or TCA cycle and oxidative phosphorylation coupling the electron transport chain in the mitochondria with chemiosmosis Aerobic catabolism of glucose requires oxygen and produces carbon dioxide and metabolic water Anaerobic glucose catabolism in animal cells involves only glycolysis and the reduction of pyruvate to lactate More efficient is making ATP net yield 38 Describe the organization and functions of the electron transport chain in aerobic respiration including its role in ATP production the ETC produces 34 of the 38 ATP molecules obtained from every molecule of glucose During glycolysis synthesis of acetylCoA and Kreb s cycle the electron carriers NAD and FADH are reduced to form NADH and FADH2 respectively These molecules are like little rechargeable batteries and when NAD and FADH are reduced this means that they accept and carry electrons and hydrogen ions H potential energy that can be used later in cellular respiration In the electron transport chain these electron carriers are oxidized transferring their electrons to the carrier molecules embedded in the ETC membrane In aerobic respiration these electrons are passed from one carrier molecule to another in a series of oxidationreduction reactions and ultimately to the final electron acceptor oxygen 02 that combines with hydrogen resulting a water H20 a metabolic waste product Then a PMF is created when the energy from each electron being passed down the chain is used to pump a proton H through each carrier molecule from one side of the membrane to the other Understand the Chemiosmotic Hypothesis The theory suggests essentially that most ATP synthesis in respiring cells comes from the electrochemical gradient across the inner membranes of mitochondria by using the energy of NADH and FADH2 formed from the breaking down of energyrich molecules such as glucose Chemiosmosis in a mitochondrion Explain the function of ATP synthase It is an important enzyme that provides energy for the cell to use through the synthesis of adenosine triphosphate ATP F0 Area of ATP synthase bound in the membrane protons flow through and cause rotation 26 27 F1 Area of ATP synthase that has conformational shape changes as a result of rotation Know the functions of proton motive force and how it is established The mitochondria use the protonmotive force to synthesize a molecule called adenosine triphosphate or ATP that your cells can use to power other processes A protein called ATP synthase is embedded in the inner membrane of the mitochondria As hydrogen ions build up outside the inner membrane they start to flow through a conduit provided by ATP synthase How it is established in more detail H is transferred to the outside of the cell while hydroxide is on the inside of the cell The energy is used to make ATP and H go into the cell and energy adds P to ADP making ATP and a less energized membrane 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 cytoplasm a glucose 2 glycolysis gt 23322222 1339 H 2 L 2 ATP quot6 2 NADH pyrl Vate mitochondrion e H 2 202 639 ELECTRON TRANSPORT 32 PHOSPHORYLATION o H7 water 0 e oxygen l TYPICAL ENERGY YIELD 36 ATP Fig6 ATP quotfield During kaaryutiie humble Respiratiun uf ne Slumse Mulemle 5mm Glyeulysis 1 xiduliun uf glumse ha pyruvie acid Pruduetiun ul 2 HAHI 2 ATP swlzas rmledevel phesphurylutiun 6 ATP uaidutive phmgphuw liun ir1 electrun frunsperl chain Elgiclmn humped ehain Preparatory Step mammalmm 1 a Furmutiun uni acetyl C i h premiums 2 DH 5 ATP Euxidutive phusphuWlaliun 1n electmn lr n p zrf chain Krebs Eyczle 1 xiduriun 111 succinyfl CGA Ire succinic i2 SGTF equivalent 11 ATP suhsri rutaIeue phusphurfluriun uid 1 2 Pm uc un 01 NADH 13 TP xidu rive phuaphawluli n 1n lex1ec rrun tr napurl Chain Prudueliun GIT 2 FADH uxid tiva phusphur yluliun iin EEETI Dn transport sheila Tuliul 313 ATP Max yield of ATP 32 NADH are worth 25 ATP FADH2 iS worth 15 ATP Glycolysis 2 ATP from substrate level phosphorylation 2 NADH Bridge step 2 NADH Krebs 2 acetyl coA 6 NADH oxidative phosphorylation 2 FADH2 oxidative phosphorylation 2 ATP by substrate level phosphorylation After doing all the calculations 32 ATP are made 28 Summarize the major features of the EntnerDoudoroff pathway 2keto3deoxy6phosphogluconate KDPG is the key intermediate It yields pyruvate and glyceraldehyde 3P Net yield 1 ATP SLP 1 NADH 1 NADHP bacteria can use this or the Meyerhof pathway where it borrows enzymes 29 30 31 Glucose Hexokinase GlucoseGP Glucose6P dehydrogenase Glucose P isomerase FructoseGP GluconateGP 6Phosphogluconate dehydratase Fructose6P 1 kinase V Fructose16P2 2Keto3deoxygluconate6P Fructose16P2 aldolase k Glyceraldehyde3P 2Keto3 l deoxygluconate P E EMP Pathway Several aldolase l Entner Doudoroff enzymes pathway l E Pentose phosphate PYTUVate 4 pathway Nature Reviews Microbiology Describe the process of fermentation its functions and its products It takes place in the absence of exogenous electron acceptor and oxygen is not needed however it is not anaerobic Pyruvate is reduced or a derivative is reduced which is important bc it needs to RECYCLE NADH How does it form ATP SLP It produces various fermentation products like lactate isopropanol Know Why bacteria produce fermentation products and how these products are useful to humans Bacteria produces fermentation so we will have fermentation products like sugar This gives us energy Distinguish between homolactic and heterolactic acid fermentation Homolactic only makes lactic acid when the acid is produced it lowers the pH of the food and acid gives the food a distinct avor and changes the consistency of the food the food it makes is cheese sour cream and yogurt 32 Heterolactic Acid makes lactic acid as well as ethanol and C02 It is responsible for swiss cheese pickles sauerkraut buttermilk and it is involved in food spoilage Distinguish between mixed acid and butanediol fermentation Explain the purpose of the MRVP test and know how it works mixed acid A fermentation byproduct of a bacteria that uses multiple pathways simultaneously Mixed acid gram makes formate lactic acid and propionate It lowers the pH of the medium so low that it gets below 5 It makes a lot of acid Other organisms use the mixed acid pathway which produces acidic end products such as lactic acetic and formic acid These acidic end products are stable and will remain acidic The medium used MRVP The reagent used methyl red The product should turn red if it is positive and that determines if it produces enough acid to go through the process of mixed acid fermentation 23 butanediol fermentation this is used for the VP test This test determines whether the microbe produces 23butanediol and acetonin as a fermentation product from glucose Barrits A and B are used as reagents The medium used MRVP Mixed Acid several pathways simultaneously 1 5 8 amp 9 see picture below Butanediol 4 VogesProskauer test detects intermediate acetonin see picture just for fun swiss cheese ususes 3 pathway Copyright The McGrawHiil Companies Inc Permission required for reproduction or display 959919 co2 Succinate Fumarate H O Malate 2 9 NADH NADH 23Butanediol e Oxaloacetate 07 Acetaldehyde CO2 Acetoin NADH u Acetolactate 002 002 NADH Pyruvate C02 Lactate CoASH 0 Ethanol NADH AcetaldeiisltJi39DH 6 e l Formate I H2 C02 Acetyl AcetyICoA ADP 00A Pi AcetoacetylCOA WP co2 ButyrylCoA w Butyryi CoA Pi GOA ADP NADH Butyraldehyde NADH r isuwrate lsopropanol E quot 1 Lactic acid bacteria Streptococcus Lactobacillus Bacillus enteric bacteria Escherichia Enterobacter Salmonella Proteus Acetone NADH Enteric bacteria Enteric bacteria 2 Yeast Zymomonas Clostridium 3 Propionic acid bacteria Propionibacterium Enteric bacteria cooowmoi 4 Enterobacter Serratia Bacillus Enteric bacteria Chapter 71 73 74 76 77 34 Describe the growth of bacterial cells binary fission binary fission two cells arise from one Process of Binarv Fission 1 Elongation 2 Invagination 35 3 Formation of a Transverse wall 4 Separation of daughter cells Elongation The cell grows longer it39s DNA is replicated Invagination Cell Membrane and cell wall start grow inward Formation of a transverse wall The Two chromosomes are separated by cell wall and cell membrane layers Separation of daughter cells The two offspring detach from one another Before binary fission occurs the cell must copy its genetic material DNA and segregate these copies to opposite ends of the cell Then the many types of proteins that comprise the cell division machinery assemble at the future division site Copyright The McGrawHill Companies Inc Permission required for reproduction or display Cell wall a A young cell at early phase of cycle 3 Cell membrane 0 Chromosome 1 O Chromosome 2 0 Ribosomes b A parent cell prepares for division by enlarging its cell wall cell membrane and overall volume c The septum begins to grow inward as the chromosomes move toward opposite ends of the cell Other cytoplasmic components are distributed to the two developing cells d The septum is synthesized completely through the cell center and the cell membrane patches itself so that there are two separate cell chambers e At this point the daughter cells are divided Some species separate completely as shown here while others remain attached forming chains doublets or other cellular arrangements Describe in detail the four phases of bacterial growth observed in a batch culture Batch culture culture incubated in a closed vessel with a single batch of medium 1 Lag phase When a microorganism is introduced into the fresh medium it takes some time to adjust with the new environment This phase is termed as Lag phase in which cellular metabolism is accelerated cells are increasing in size but the bacteria are not able to replicate and therefore no increase in cell mass The length of the lag phase depends directly on the previous growth condition of the organism When the microorganism growing in a rich medium is inoculated into nutritionally poor medium the organism will take more time to adapt with the new environment The organism will start synthesising the necessary proteins coenzymes and vitamins needed for their growth and hence there will be a subsequent increase in the lag phase Similarly when an organism from a nutritionally poor medium is added to a nutritionally rich medium the organism can easily adapt to the environment it can start the cell division without any delay and therefore will have less lag phase it may be absent 2 Exponential or Logarithmic log phase During this phase the microorganisms are in a rapidly growing and dividing state Their metabolic activity increases and the organism begin the DNA replication by binary fission at a constant rate The growth medium is exploited at the maximal rate the culture reaches the maximum growth rate and the number of bacteria increases logarithmically exponentially and finally the single cell divide into two which replicate into four eight sixteen thirty two and so on That is 20 21 22 23 2n n is the number of generations This will result in a balanced growth The time taken by the bacteria to double in number during a specified time period is known as the generation time The generation time tends to vary with different organisms Ecoli divides in every 20 minutes hence its generation time is 20 minutes and for Staphylococcus aureus it is 30 minutes 3 Stationary phase As the bacterial population continues to grow all the nutrients in the growth medium are used up by the microorganism for their rapid multiplication This result in the accumulation of waste materials toxic metabolites and inhibitory compounds such as antibiotics in the medium This shifts the conditions of the medium such as pH and temperature thereby creating an unfavourable environment for the bacterial growth The reproduction rate will slow down the cells undergoing division is equal to the number of cell death and finally bacterium stops its division completely The cell number is not increased and thus the growth rate is stabilised If a cell taken from the stationary phase is introduced into a fresh medium the cell can easily move on the exponential phase and is able to perform its metabolic activities as usual 4 Decline or Death phase The depletion of nutrients and the subsequent accumulation of metabolic waste products and other toxic materials in the media will facilitates the bacterium to move on to the Death phase During this the bacterium completely loses its ability to reproduce Individual bacteria begin to die due to the unfavourable conditions and the death is rapid and at uniform rate The number of dead cells exceeds the number of live cells Some organisms which can resist this condition can survive in the environment by producing endospores Log or exponential growth phase 2 It 8 3 Lag g phase E 3 B 6 8 l 0 5 Time hr Copyright 2004 Pearson Education Inc piblishing as Ben39amin Cummings 36 Be able to label a growth curve see picture in 35 and be able to label this 37 Define generation time and be able to calculate it 1 N t N 0 X 2 Nt is the population at time t N0 is the initial population number 11 number of generations for t n 33 log Nt log N0 g tn look at this example n 33 log Nt log NO Nt 10 X 108 N0 50 X 107 n 338 77 n 1 generation during t t 2 time interval g tn 2 h generation 1x108 gt 8x107 6x107 4x107 3x107 Cellsml lt 2x107 I L 1x107 0 1 2 3 4 5 Time h Figure 67b Brock Biology of Microorganisms 1 lie 2006 Pearson Prentice Hall Inc 38 Explain the methods of measuring the growth number of microbes microscopic count plating methods turbidity measurements Direct Total cell count count the number of cells that are observed in the medium Counting chamber Electronic counter Viable cell counts count the number of CFUS that are culturable from the medium Plating techniques count colonies each colony 1 bacteria Membrane filter for dilute samples like drinking water Indirect Dry weight bacteria gets water all out of it and weigh the bacteria Turbidity absorbance of light to see how much bacteria is there You don t actually get a number from indirect though Microscopic counting To calculate number per milliliter of sample 12 cells x 25 large squares x50x 103 15x 107 Number mm2 I Number mm3 b Sample added here care must Microscopic observation all be taken not to allow overflow cells are counted in large square N b 3 I space between coverslip and 12 cells in practice several um er cm m slide is 002 mm 51 0 mm Whole squares are counted and grid has 25 large squares a total the numbers averaged area of 1 mm2 and a total volume of 002 mm3 Figure 69 Brock Biology of Microorganisms 11e 2006 Pearson Prentice Hall Inc Plating method plate dilutions of population on suitable solid medium9 count number of colonies9calculate number of cells in original population Population size expressed as colony forming units CFUmL Usually underestimate of the real number you re counting because the CFU could have cells stuck together or counting errors 1 w 7 Sampleto quot 7 r be counted Dilution gt 1 ml 1 ml 1 ml 1 ml 1 ml VF WF VF WF W zl39 i39h H H l fl 110 1100 113903 110 0s via6 10 102 103 104 105 106 Plate 1 ml samples l l 2 0 Too many colonies colonies colonies colonies colonies tocount 159 x 103 159 x 105 Plate Dilution Cells colonyforming count factor units per milliliter of original sample Figure 61 1 Brock Biology of Microorganisms 1 1e D 2006 Pearson Prentice Hall Inc Turbidity Incident quot l39 htl Filter or l39ght39 0 Sample 399 Photocell measures Recorder prism 540 nm containing unscattered light I units cells 0 I Spectrophotometer Klett photometer optical density OD KIett units O 0 0002 Log I Figure 61 2a Brock Biology of Microorganisms 11e 2006 Pearson Prentice Hall Inc More cells9 more absorbed scattered light less transmitted unscattered light detected that comes on the other side 39 Describe how water activity pH temperature and oxygen affect microbial growth Water activity amount of water available to organisms aw values range from 0 to 1 pure water available to the organism water associated with solutes is unavailable to microorganisms higher solute 9 lower aw adaptations hypotonic solutions most bacteria likes this solution use mechanosensitive MS channels in membrane to allow solutes to leave less water comes into cell The MS makes the cell swell and the channel will open so that the solutes can leave through the channels the amount of solutes go down and water in the cell hypertonic solutions increase internal solute concentration with compatible solutes9 more water comes into cell bc if they raise solutes concentration For more understanding of what these are refer to the picture below Nonhalophile exEcoli does not require NaCl can grow if lt 1 NaCl Halotolerant9don t have to have salt but can withstand it ex staph Halophiles9 exzocean requires NaCl for growth grOW optimally at gt02 M 1 15 NaCl extreme halophiles9ex great salt lakearchaeons in the dead sea require 2 62 M 15 30 NaCl mm Mum Example Example llllo 39 Staphylococcus Vibrio fischeri Example aureus Halobacterium salinarum Growth rate llonlmlophile Example Escherichia coli 0 NaCl Figure 623 Brock Biology of Microorganisms We 399 2006 Pearson Prentice Hall Inc pH pH is the measure of the relative acidity of a solution and it is a negative logarithm of the hydrogen ion concentration Acidophiles growth optimum between pH 0 and pH 55 Neutrophils growth optimum between pH 5 5 and pH 7 Alkailophiles alkalophiles growth optimum between pH 85 and pH 115 Ex organism living in the oceansome can be neutrophils but many like oceans response to pH most microbes maintain an internal pH near neutrality Acid shock proteins many microbes change the pH of their habitat by producing acidic or basic waste products Acid shock protects enzymes from acid to a certain point and can renature enzymes and prevents denaturation if they go in acid Temperature microbes cant regulate internal temperature exhibit distinct cardinal growth temperatures Minimumenzymes work slowermembrane starts to gel and everything slows down saturated levels Maximumenzymes work faster Optimum closer to max than minimum over optimum denature and collapse of membrane psychrophiles lt 0 20 C optimum lt 150 C Psvchrotoph overlaps mesophile range and can grow in the refrigerator 9 0 35 C optimum 20 30 C mesophiles middle temp 9 15 45 C optimum 20 45 C thermophiles 9 45 85 C optimum 55 65 C hyperthermophiles9 65 113 C optimum 85 113 C Oxygen Affect aerobe grows in presence of atmospheric oxygen which is z 20 02 Obligate strict aerobe requires 02 Anaerobe grows in the absence of 02 obligate strict anerobe usually killed in presence of 02 Microaerophile water columns requires 2 10 02 Facultative aerobeanaerobe does not require 02 but grows better in its presence aerotolerant anaerobe grows with or without 02 40 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 Table 64 Oxygen relationships oi microorganisms Group Relationship to 02 Type of metabolism Example Habitat Aerobes Obligate Required Aerobic respiration M icrococcus luteus B Skin dust Facultative Not required but growth Aerobic respiration anaerobic Escherichia coli B Mammalian large better with 02 respiration fermentation intestine Microaerophilic Required but at levels Aerobic respiration Spirilhmz volutans B Lake water lower than atmospheric Anaerobes Aerotolerant Not required and growth Fermentation Streptococcus pyogenes B Upper respiratory tract no better when 02 present Obligate Harmful or lethal Fermentation or anaerobic Methanobacterium A Sewage sludge digestors respiration formicicmn anoxic lake sediments quot Letters in parentheses indicate phylogenetic status 8 Bacteria A Archaaa Representatives of either domain of prokaryotes are known in each category Most eukaryotes are obligate aerobes but facultative aerobes for example yeast and obligate anaerobes for example certain protozoa and fungi are known 1 Listed are typical habitats of the example organism Table 64 Brock Biology of Microorganisms lle 2006 Pearson Prentice Hall Inc 41 Explain how microorganisms protect themselves from the toxic products of oxygen reduction a c Figure 625 Brock Biology of Microorganisms 1 1e 2006 Pearson Prentice Hall Inc a Obligate aerobe b Obligate anerobe c Facultative d Microaerophile e Aerotolerant anaerobe oxygen easily reduced to toxic reactive oxygen species ROS superoxide radical oxygen with 1 unpaired e hydroxide hydroxy1 radicalmost lethalneutral hydroxide Aerobes produce protective enzymes superoxide dismutase SOD catalase peroxidase 02 e39 gt 02 Superoxide 0239e39 2 H gt H202 Hydrogen peroxide H202e H gt H20 OH Hydroxyl radical OHe H gt H20 Water Overall 02 4equot 4H gt2 H20 Figure 627 Brock Biology of Microorganisms Ile O 2006 Pearson Prentice Hall Inc Oxic zone Anoxic zone a Caioluse H202 H202 2 H20 02 b Peroxidase H202 H gt 2 H20 NAD c Superoxide dismuiuse 02 02 2 02 d Superoxide dismuiusecutoluse in combination 402 4H2 H20 3 02 e Superoxide reduciose 02 2 H cyt Creduced I4202 cyt coxidized Figure 628 Brock Biology of Microorganisms 11Ie 3 2006 Pearson Prentice Hall Inc aCatalase can be used to get rid of hydrogen peroxide produces oxygen b Peroxidases can get rid of hydrogen peroxide but it needs NADH c Makes hydrogen peroxide d Get rid of both most combo used by aerobes facultative e Gets rid of superoxide radical to make hydrogen peroxide used in obligate anaerobes DISEASES 42 For each of the microbial diseases listed below be able to brie y describe the following a cause name of bacterium or virus b general characteristics of the microbe bacteria Gram reaction and shape viruses type of genome and shape 0 route of transmission d characteristic symptoms Strep Throat Streptococcal pharyngitis Cause Strep throat is caused by infection with Group A Streptococcus GAS bacteria specifically Streptococcus pyogenes The streptococcal infection invades the pharyngeal tissue and causes a localized in ammatory reaction of the throat and tonsils These bacterial organisms are often found in the throat or on the skin and are responsible for other illnesses as well such as impetigo a skin infection Characteristics aerobic gram positive Route of transmission The bacteria are spread through contact with droplets after an infected person coughs or sneezes Characteristic symptoms fever tiny red sports in the back of your thorat headaches vomiting body aches Cholera Cause Eating fooddrinks that are contaminated with Vibrio Cholerae Characteristics gram negative motile Route of transmission through the mouth Characteristic symptoms leg cramps diarrhea vomintting losing a rapid rate of body uids Bacterial Meningitis Meningococcal caused by N meningitides Cause Meningococcal disease is caused by the bacterium Neisseria meningitidis Characteristics gram negative nonspore forming nonmotile Route of transmission spread by person to person by exchanging respiratorythroat secretions during close contact but it is not spread by casual contact Characteristic symptoms nausea vomiting increased sensitivity to light altered mental status Pregnant women need to be careful because it can be passed along to their babies Lyme Disease Cause Lyme disease is caused by the bacterium Borrelia burgdorferi carried primarily by blacklegged or deer ticks The ticks are brown and when young often no bigger than a poppy seed which can make them nearly impossible to spot To contract Lyme disease an infected deer tick must bite you Characteristics spirochete parasite gram negative Route of transmission bites Characteristic symptoms rash memory problems pain and weakness in arms and legs Infectious Mononucleosis Cause quotmonoquot quotkissing diseasequot and glandular fever are all terms popularly used for the very common infection caused by the EpsteinBarr virus EBV Characteristics capsid with spikes Route of transmission person to person contact Characteristic symptoms fever fatigue malaise and sore throat Gas Gangrene Clostridial Mvonecrosis caused by C perfringens Cause Gas gangrene is caused by bacteria called Clostridium perfringens C perfringens In some cases it can be caused by Group A Streptococcus Characteristics gram positive spore forming Route of transmission food poisoning Characteristic symptoms swelling blisters that contain gas bubbles near the infection increase heart rate and skin turns from pale to brownishred gt Even if we do not cover these diseases in class you are still responsible for the information NOTE Unless otherwise stated you are responsible for all of the unit objectives even if they are not covered in lecture see textbook UNIT 2 ANIMATIONS TO WATCH httphigheredmheducationcomsites0073375268student viewOindexhtml Chapter 3 Bacterial Locomotion Chemotaxis in E coli first part only omit the part discussing the chemoreceptors involved Bacterial Endo Spore Formation httphigheredmheducationcomsites0073402400student viewOindexhtml Cha ter 11 Electron Transport System and ATP Synthesis Electron Transport System and Formation of ATP How Glycolysis Works How NAD Works How the Krebs Cycle Works just watch for an overview Chapter 7 Binary Fission Biofilms


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