Solution Manual For Microbiology: An Introduction, 13th Edition

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1CHAPTER1The Microbial World and YouGlobal EditionLearning ObjectivesCheck Your Understanding1-1List several ways in which microbesaffect our lives.Describe some of the destructive and beneficialactions of microbes.1-2Definemicrobiome,normal microbiota,andtransient microbiota.What percentage of all cells in the human bodyare bacterial cells?1-3Recognize the system of scientificnomenclature that uses two names: agenus and a specific epithet.Distinguish a genus from a specific epithet.1-4Differentiate the major characteristics ofeach group of microorganisms.Which groups of microbes are prokaryotes?Which are eukaryotes?1-5List the three domains.What are the three domains?1-6Explain the importance of observationsmade by Hooke and van Leeuwenhoek.What is the cell theory?1-7Compare spontaneous generation andbiogenesis.What evidence supported spontaneousgeneration?1-8Identify the contributions to microbiol-ogy made by Needham, Spallanzani,Virchow, and Pasteur.How was spontaneous generation disproved?1-9Explain how Pasteur’s work influencedLister and Koch.Summarize in your own words the germ theoryof disease.1-10Identify the importance of Koch’spostulates.What is the importance of Koch’s postulates?1-11Identify the importance of Jenner’swork.What is the significance of Jenner’s discovery?1-12Identify the contributions to microbiol-ogy made by Ehrlich and Fleming.What was Ehrlich’s “magicbullet”?1-13Definebacteriology,mycology,parasit-ology,immunology,andvirology.Definebacteriology,mycology,parasitology,immunology, andvirology.1-14Explain the importance of microbialgenetics, molecular biology, andgenomics.Differentiate microbial genetics, molecularbiology, and genomics.

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2INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,GE, 13e1-15List at least four beneficial activities ofmicroorganisms.Name two beneficial uses of bacteria.1-16Name two examples of biotechnologythat use recombinant DNA technologyand twoexamples that do not.Differentiate biotechnology from recombinantDNA technology.1-17Defineresistance.Differentiate normal microbiota and infectiousdisease.1-18Definebiofilm.Why are biofilms important?1-19Defineemerging infectiousdisease.What factors contribute to the emergence of aninfectious disease?New in This Edition•The resurgence in microbiology is highlighted in sections on the Second and ThirdGolden Ages of Microbiology.•The Emerging Infectious Diseases section has been updated.•A discussion of normal microbiota and the human microbiome has been added.Chapter SummaryMicrobes in Our Lives (p.28)The Microbiome (pp.28–29)ASM 5.4: Microorganisms, cellular and viral, can interact with bothhuman and nonhuman hosts in beneficial, neutral, or detrimentalways.ASM 6.2: Microorganisms provide essential models that give usfundamental knowledge about life processes.1.Living things too small to be seen with the unaided eye are called microorganisms.2.Microorganisms are important in maintaining Earth’s ecological balance.3.Everyone has microorganisms in and on the body; these make up the normal microbiotaor human microbiome. The normal microbiota are needed to maintain good health.4.Some microorganisms are used to produce foods and chemicals.5.Some microorganisms cause disease.Naming and Classifying Microorganisms (pp.30–32)ASM 2.4: While microscopic eukaryotes (e.g., fungi, protozoa, andalgae) carry out some of the same processes as bacteria, many of thecellular properties are fundamentally different.Nomenclature (p.30)

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CHAPTER 1 The Microbial World and You31.In a nomenclature system designed by Carolus Linnaeus (1735), each living organism isassigned two names.2.The two names consist of a genus and a specific epithet, both of which are underlined oritalicized.Types of Microorganisms (pp.30–32)3.Bacteria are unicellular organisms. Because they have no nucleus, the cells are describedas prokaryotic.4.Most bacteria have a peptidoglycan cell wall; they divide by binary fission, and they maypossess flagella.5.Bacteria can use a wide range of chemical substances for their nutrition.6.Archaea consist of prokaryotic cells; they lack peptidoglycan in their cell walls.7.Archaea include methanogens, extreme halophiles, and extreme thermophiles.8.Fungi (mushrooms, molds, and yeasts) have eukaryotic cells (cells with a true nucleus).Most fungi are multicellular.9.Fungi obtain nutrients by absorbing organic material from their environment.10.Protozoa are unicellular eukaryotes.11.Protozoa obtain nourishment by absorption or ingestion through specialized structures.12.Algae are unicellular or multicellular eukaryotes that obtain nourishment by photosyn-thesis.13.Algae produce oxygen and carbohydrates that are used by other organisms.14.Viruses are noncellular entities that are parasites of cells.15.Viruses consist of a nucleic acid core (DNA or RNA) surrounded by a protein coat. Anenvelope may surround the coat.16.The principal groups of multicellular animal parasites are flatworms and roundworms,collectively called helminths.17.The microscopic stages in the life cycle of helminths are identified by traditionalmicrobiological procedures.Classification of Microorganisms (p.32)18.All organisms are classified into one of three domains: Bacteria, Archaea, and Eukarya.Eukarya include protists, fungi, plants, and animals.A Brief History of Microbiology (pp.32–40)ASM 7.4: Ability to understand the relationship between science andsocietyThe First Observations (pp.32–33)1.Hooke’s observations laid the groundwork for development of the cell theory, theconcept that all living things are composed of cells.2.Anton van Leeuwenhoek, using a simple microscope, was the first to observemicroorganisms (1673).

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4INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,GE, 13eThe Debate over Spontaneous Generation (pp.33–35)3.Until the mid-1880s, many people believed in spontaneous generation, the idea thatliving organisms could arise from nonliving matter.4.Francesco Redi demonstrated that maggots appear on decaying meat only when flies areable to lay eggs on the meat (1668).5.John Needham claimed that microorganisms could arise spontaneously from heatednutrient broth (1745).6.Lazzaro Spallanzanirepeated Needham’s experiments and suggested that Needham’sresults were due to microorganisms in the air entering his broth (1765).7.Rudolf Virchow introduced the concept of biogenesis: living cells can arise only frompreexisting cells (1858).8.Louis Pasteur demonstrated that microorganisms are in the air everywhere and offeredproof of biogenesis (1861).9.Pasteur’s discoveries led to the development of aseptic techniques used in laboratory andmedical procedures to prevent contamination by microorganisms.The First Golden Age of Microbiology (pp.35–37)10.The science of microbiology advanced rapidly between 1857 and 1914.11.Pasteur found that yeast ferment sugars to alcohol and that bacteria can oxidize thealcohol to acetic acid.12.A heating process calledpasteurizationis used to kill bacteria in some alcoholicbeverages and milk.13.Agostino Bassi (1835) and Pasteur (1865) showed a causal relationship betweenmicroorganisms and disease.14.Joseph Lister introduced the use of a disinfectant to clean surgical wounds in order tocontrol infections in humans (1860s).15.Robert Koch proved that microorganisms cause disease. He used a sequence ofprocedures, now called Koch’s postulates (1876), that are used today to prove that aparticular microorganism causes a particular disease.16.In 1798, Edward Jenner demonstrated that inoculation with cowpox material provideshumans with immunity to smallpox.17.About 1880, Pasteur discovered that avirulent bacteria could be used as a vaccine forfowl cholera; he coined the wordvaccine.18.Modern vaccines are prepared from living avirulentmicroorganisms or killed pathogens,from isolated components of pathogens, and by recombinant DNA techniques.The Second Golden Age of Microbiology (pp.37–40)19.The Second Golden Age began with the discovery of penicillin’s effectiveness againstinfections.20.Two types of chemotherapeutic agents are synthetic drugs (chemically prepared in thelaboratory) and antibiotics (substances produced naturally by bacteria and fungi to inhibitthe growth of other microorganisms).

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CHAPTER 1 The Microbial World and You521.Paul Ehrlich introduced an arsenic-containing chemical called salvarsan to treat syphilis(1910).22.Alexander Fleming observed that thePenicilliumfungus inhibited the growth of abacterial culture. He named the active ingredient penicillin (1928).23.Researchers are tackling the problem of drug-resistant microbes.24.Bacteriology is the study of bacteria, mycology is the study of fungi, and parasitology isthe study of parasitic protozoa and worms.25.The study of AIDS and analysis of the action of interferons are among the currentresearch interests in immunology.26.New techniques in molecular biology and electron microscopy have provided tools foradvancing our knowledge of virology.27.The development of recombinant DNA technology has helped advance all areas ofmicrobiology.The Third Golden Age of Microbiology (p.40)28.Microbiologists are using genomics, the study of all of an organism’s genes, to studymicrobiomes in different environments.Microbes and Human Welfare (pp.40–42)ASM 4.5: Cell genomes can be manipulated to alter cell function.ASM 6.1: Microbes are essential for life as we know it and theprocesses that support life (e.g., in biogeochemical cycles and plantand/or animal microflora).ASM 6.2: Microorganisms provide essential models that give usfundamental knowledge about life processes.ASM 6.3: Humans utilize and harness microorganisms and theirproducts.1.Microorganisms degrade dead plants and animals and recycle chemical elements to beused by living plants and animals.2.Bacteria are used to decompose organic matter in sewage.3.Bioremediation processes use bacteria to clean up toxic wastes.4.Bacteria that cause diseases in insects are being used as biological controls of insectpests. Biological controls are specific for the pest and do not harm the environment.5.Using microbes to make products such as foods and chemicals is called biotechnology.6.Usingrecombinant DNA, bacteria can produce important substances such as proteins,vaccines, and enzymes.7.In gene therapy, viruses are used to carry replacements for defective or missing genesinto human cells.

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6INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,GE, 13e8.Genetically modified bacteria are used in agriculture to protect plants from frost andinsects and to improve the shelf life of produce.Microbes and Human Disease (pp.42–45)ASM 5.4: Microorganisms, cellular and viral, can interact with bothhuman and nonhuman hosts in beneficial, neutral, or detrimentalways.1.The disease-producing properties of a species of microbe and the host’s resistance areimportant factors in determining whether a person will contract a disease.2.Bacterial communities that form slimy layers on surfaces are called biofilms.3.An infectious disease is one in which pathogens invade a susceptible host.4.An emerging infectious disease (EID) is a new or changing disease showing an increasein incidence in the recent past or a potential to increase in the near future.Contributions to the field of microbiology by the following individuals are noted in this chapter:Oswald AveryAgostino BassiFrançoise Barré-SinoussiGeorge BeadleMartinusBeijerinckFrancisCrickPaul EhrlichAlexander FlemingRobert HookeDmitri IwanowskiFrançois JacobEdward JennerRobert KochRebecca LancefieldAntoine LavoisierJoshua LederbergCarolus LinnaeusJoseph ListerColin MacLeodMaclyn McCartyCésar MilsteinJacques MonodJohn NeedhamLouis PasteurFrancesco RediIgnaz SemmelweisLazzaro SpallanzaniWendell StanleyEdward TatumYouyou TuAnton van LeeuwenhoekRudolf VirchowJames WatsonChaim WeizmannSergei WinogradskyCarl WoeseThe LoopThe chapter defines organisms studied in microbiology. Topics introduced in the overview ofmicrobiology can be covered in more depth by reading the following sections:Bioremediationp.41, Chapter 2 (p.57)ClassificationChapter 10Emerging infectious diseasespp.43–45Industrial microbiology/biotechnologyChapters 9 and 28Koch’s postulatesp.36, Chapter 14 (Figure 14.3)Vaccinespp.36–37, Chapter 18Biofilmsp.42, Chapter 6 (pp.183–184)Exploring the MicrobiomeHowDoes YourMicrobiome Grow?

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CHAPTER 1 The Microbial World and You, GE7This introductory chapter contains an introductory segment on how the microbiome of peoplemay vary depending on their diet.Discussion questions:•Is the ability to break down red algae a desirable trait (from the perspective ofhumans) or is it just beneficial to bacteroides?•If the ability to break down red algae is indeed beneficial, should the FDA considerallowing raw algae? What are the potential risks and benefits?•A related topic to discuss is how infants acquire their microbiome. A January 2017article discusses vertical transmission of microbes. Blum, K. (2017) Researchers UseInnovative Methods to Study Vertical Transmission of Microbes.https://www.asm.org/index.php/mbiosphere/item/5474-researchers-use-innovative-methods-to-study-vertical-transmission-of-mi-crobes?utm_source=TrendMD&utm_medium=cpc&utm_campaign=mBiosphere_TrendMD_0AnswersFigure QuestionsFigureQuestionAnswer1.1How do we benefit from the produc-tion of vitamin K by microbes?Vitamin K is necessary forblood clotting.1.2How are bacteria, archaea, fungi, pro-tozoa, algae, and viruses distinguishedon the basis of cellular structure?Bacteria are prokaryotic with peptidoglycancell walls.Archaea are prokaryotes lacking pepti-doglycan.Fungi are eukaryotes with chitin cell walls.Protozoa are unicellular eukaryotes withoutcell walls.Algae are unicellular eukaryotes withchloroplasts and cell walls.Viruses are not composed of cells. Theyconsist of a protein coat enclosing a nucleicacid.1.3Whywas van Leeuwenhoek’s discov-ery so important?It led the way to look for microbial causesof disease and changes in food.1.5Why do you think theFirstGoldenAge of Microbiology occurred when itdid?Technology (microscopes) combined withPasteur’s discovery that microbes cause“diseases” of food.1.6Why do you think penicillin is nolonger as effective as it once was?Overuse has selected for penicillin-resistantbacteria.1.7What advances occurred during theSecond Golden Age of Microbiology?Discovery and development of antibioticsand other antimicrobial agents, developmentof techniques for sequencing DNA and forproducing monoclonal antibodies.

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8INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,13e, GE1.8How do you think parasitic wormssurvive and live off a human host?Worms could activelyingest human tissueor could absorb nutrients from the host’sintestinal contents.1.9Why is it important to identify strepto-cocci quickly?Streptococci include several importantpathogens includingStreptococcuspyogenes,Streptococcus agalactiae, andStreptococcus pneumoniae.1.10How does a biofilm’s protective barriermake it resistant to antibiotics?The barrier makes it difficult for the antibi-otics to penetrate the biofilm and access themicroorganisms.Review1.Rudolf Virchow’s concept ofbiogenesis, stating that living cells arise only from preexist-ing ones, challenged the case for spontaneous generation.2.a.Certain microorganisms cause diseases in insects. Microorganisms that kill insects canbe effective biological control agents because they are specific for the pest and do notpersist in the environment.b.Carbon, oxygen, nitrogen, sulfur, and phosphorus are required for all living organisms.Microorganisms convert these elements into forms that are useful for other organisms.Many bacteria decompose material and release carbon dioxide into the atmospherethat plants use. Some bacteria can take nitrogen from the atmosphere and convert itinto a form that can be used by plants and other microorganisms.c.Normal microbiota are microorganisms that are found in and on the human body.They do not usually cause disease and can be beneficial.d.Organic matter in sewage is decomposed by bacteria into carbon dioxide, nitrates,phosphates, sulfate, and other inorganic compounds in a wastewater treatment plant.e.Recombinant DNA techniques have resulted in insertion of the gene for insulinproduction into bacteria. These bacteria can produce human insulin inexpensively.f.Microorganisms can be used as vaccines. Some microbes can be geneticallyengineered to produce components of vaccines.g.Biofilms are aggregated bacteria adhering to each other and to a solid surface.3.a.1,3d.2g.6b.8e.5h.7c.1, 4, 5f.34.a.7d.2g.1b.4e.6c.3f.55.a.11g.10m.7b.14h.2n.5c.15i.1o.6d.17j.12p.8

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CHAPTER 1 The Microbial World and You, GE9e.3k.18q.13f.9l.4r.166.No.E. colican be beneficial for health as they aid in digestion and vitamin production.However, infection by a strain calledE. coliO157:H7 causes bloody diarrhea. Certainspecies of bacteria of the generaPseudomonasandBacillusare among the mostcommonly used microbes for cleaning up pollutants.7.Virus8.Multiple Choice1.b6.c2.a7.c3.d8.a4.c9.d5.b10.aAnalysis1.Pasteur showed that life comes from preexisting life. The microorganisms that producedchemical and physical changes in beef broth and wine came from a few cells that enteredthe liquids from dust, containers, or the air. After showing that microorganisms couldboth grow on and change organic matter, Pasteur and others began to suspect thatdiseases were the result of microorganisms growing on living organic matter.2.Semmelweis had observed an increased incidence of fever when medical studentsworked in obstetrics, as compared to the incidence during the students’ summer break.The medical students were carrying bacteria from the autopsy room. Lister observed thatcompound bone fractures could result in death, whereas recovery from simple fracturesoccurred without incident.3.Erwinia amylovorais the correct way to write this scientific name. Scientific names canbe derived from the names of scientists. In this case,Erwiniais derived from Erwin F.Smith, an American plant pathologist. Scientific names also can describe the organism,its habitat, or its niche.E. amylovorais a pathogen of plants (amylo= starch,vora= eat).4.There are many! Check the dairy section for fermented products, such as sour cream,yogurt, and cheese. Protein supplements often are yeasts. Bread, wine, and beer areproducts of yeasts and some bacteria. Sauerkraut is cabbage that has been fermented bylactobacilli. Vinegar is produced by bacterial growth on ethyl alcohol (wine). Xanthan, athickener in many foods, is made byXanthomonasbacteria.

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10INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,13e, GE5.Factors contributing to infectious disease include mutations in existing organisms, spreadof diseases to new areas, ecological disturbances such as deforestation, lack of immun-ization, pesticide resistance, and antibiotic resistance.Clinical ApplicationandEvaluation1.a.Antibiotic treatment (e.g., penicillin, ampicillin).b.The warm and humid environment of tropical regions during the rainy season is veryconducive to the growth ofLeptospira.Also, when rain water contaminated byLepto-spiramixes with sources of drinking water, the incidence of leptospirosis increases.2.Pasteur showed that microbes were omnipresent and were responsible for “diseases”(i.e., spoilage) of food; Lister reasoned that these microbes might be responsible fordiseases of people. Neither Lister nor Pasteur proved that microbes caused diseases.Koch provided a repeatable proof to demonstrate that a microbe causes a disease.3.According to the U.S. FDA there is not enough evidence that use antibacterial soaps anddetergent in the home is better than plain soap and water. Questions persist regardinglong-term safety of antibacterial products and laboratory studies suggest that householduse may contribute to bacterial resistance.Case Study: Are Ulcers an Infectious Disease?BackgroundIn 1981, the following information came to the attention of Barry Marshall, a gastroenterolo-gist at the Royal Perth Hospital in Australia. Household members of ulcer patients do notdevelop antibodies againstHelicobacter.However, clinical staff involved in obtaining biopsysamples from ulcer patients developed antibodies againstHelicobacter.If acid-suppressivetherapy is combined with antibiotics, ulcers usually do not recur. Marshall concluded thatulcers are an infectious disease.QuestionsWhat caused Marshall to reach his conclusion? What additional proof would be needed?The SolutionThe presence of antibodies againstHelicobacteris evidence of current or prior infection bythe organism. Exchange of bacteria of the intestinal and skin microbiota, which is normalamong household members, does not transmitHelicobacter,but direct contact with stomachcontents does. Marshall collected the additional proof by demonstrating Koch’s postulates.Healthy volunteers were inoculated withHelicobacter; they developed symptoms of thedisease; and theHelicobacterwas recovered from them.

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11CHAPTER2Chemical PrinciplesGlobal EditionLearning ObjectivesCheck Your Understanding2-1Describe the structure of an atom and itsrelation to the physical properties ofelements.How does146Cdiffer from126C?What is theatomic number of each carbon atom? Theatomicmass?2-2Defineionicbond,covalent bond,hydro-gen bond,molecular weight,andmole.Differentiate an ionic bond from a covalentbond.2-3Diagram three basic types of chemicalreactions.This chemical reaction below is used toremove chlorine from water. What type ofreaction is it?HClO + Na2SO3→Na2SO4+ HCl2-4List several properties of water that areimportant to living systems.Why is the polarity of a water moleculeimportant?2-5Defineacid,base,salt, andpH.Antacids neutralize acid by the followingreaction.Mg(OH)2+ 2HCl→MgCl2+ H2OIdentify the acid, base, and salt.2-6Distinguish organic and inorganiccompounds.Defineorganic.2-7Definefunctional group.Add the appropriate functional group(s) tothe ethyl group below to produce each of thefollowing compounds: ethanol, acetic acid,acetaldehyde, ethanolamine, diethyl ether.2-8Identify the building blocks of carbohy-drates.Give an example of a monosaccharide, adisaccharide, and a polysaccharide.2-9Differentiate simple lipids, complexlipids, and steroids.How do simple lipids differ from complexlipids?2-10Identify the building blocks and structureWhat two functional groups are in all amino

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12INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,GE, 13eof proteins.acids?2-11Identify the building blocks of nucleicacids.How do DNA and RNA differ?2-12Describe the role of ATP in cellularactivities.Which can provide more energy for a cell andwhy: ATP or ADP?New inThis Edition•A discussion of the relationship between starch and normal microbiota has been added.Chapter SummaryIntroduction (p.50)ASM3.2: The interactions of microorganisms among themselves andwith their environment are determined by their metabolic abilities(e.g., quorum sensing, oxygen consumption, nitrogentransformations).ASM 6.2: Microorganisms provide essential models that give usfundamental knowledge about life processes.1.The science of the interaction between atoms and molecules is called chemistry.2.The metabolic activities of microorganisms involve complex chemical reactions.3.Microbes break downnutrients to obtain energy and to make new cells.The Structure of Atoms (pp.51–52)1.An atom is the smallest unit of a chemical element that exhibits the properties of thatelement.2.Atoms consist of a nucleus, which contains protons and neutrons, and electrons, whichmove around the nucleus.3.The atomic number is the number of protons in the nucleus; the total number of protonsand neutrons is the atomicmass.Chemical Elements (p.51)4.Atoms with the same number of protons and the same chemical behavior are classified asthe same chemical element.5.Chemical elements are designated by abbreviations called chemical symbols.6.About 26 elements are commonly found in living cells.7.Atoms that have the same atomic number (are of the same element) but different atomicmassesare called isotopes.Electronic Configurations (p.52)8.In an atom, electrons are arranged around the nucleus in electron shells.

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CHAPTER 2 Chemical Principles139.Each shell can hold a characteristic maximum number of electrons.10.The chemical properties of an atom are due largely to the number of electrons in itsoutermost shell.How Atoms Form Molecules: Chemical Bonds (pp.53–55)1.Molecules are made up of two or more atoms; molecules consisting of at least twodifferent kinds of atoms are called compounds.2.Atoms form molecules in order to fill their outermost electron shells.3.Attractive forces that bind two atomstogether are called chemical bonds.4.The combining capacity of an atom—the number of chemical bonds the atom can formwith other atoms—is its valence.Ionic Bonds (p.53)5.A positively or negatively charged atom or group of atoms is called an ion.6.A chemical attraction between ions of opposite charge is called an ionic bond.7.To form an ionic bond, one ion is an electron donor, and the other ion is an electronacceptor.Covalent Bonds (pp.53–54)8.In a covalent bond, atoms share pairs of electrons.9.Covalent bonds are stronger than ionic bonds and are far more common in organicmolecules.Hydrogen Bonds (pp.54–55)10.A hydrogen bond exists when a hydrogen atom covalently bonded to one oxygen ornitrogen atom is attracted to another oxygen or nitrogen atom.11.Hydrogen bonds form weak links between different molecules or between parts of thesame large molecule.MolecularMassand Moles (p.55)12.The molecularmassis the sum of the atomicmassesof all the atoms in a molecule.13.A mole of an atom, ion, or molecule is equal to its atomic or molecularmassexpressed ingrams.Chemical Reactions (pp.56–57)1.Chemical reactions are the making or breaking of chemical bonds between atoms.2.A change of energy occurs during chemical reactions.3.Endergonic reactions require more energy than they release; exergonic reactions releasemore energy.4.In a synthesis reaction, atoms, ions, or molecules are combined to form a largermolecule.

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14INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,GE, 13e5.In a decomposition reaction, a larger molecule is broken down into its componentmolecules, ions, or atoms.6.In an exchange reaction, two molecules are decomposed, and their subunits are used tosynthesize two new molecules.7.The products of reversible reactions can readily revert to form the original reactants.Important Biological Molecules (pp.57–73)Inorganic Compounds (pp.57–59)1.Inorganic compounds are usually small, ionically bonded molecules.Water (pp.57–58)2.Water is the most abundant substance in cells.3.Because water is a polar molecule, it is an excellent solvent.4.Water is a reactant in many of the decomposition reactions of digestion.5.Water is an excellent temperature buffer.Acids, Bases, and Salts (p.58)6.An acid dissociates into H+and anions.7.A base dissociatesintoOHandcations.8.A salt dissociates into negative and positive ions,neither of which is H+or OH.Acid–Base Balance: The Concept of pH (pp.58–59)9.The termpHrefers to the concentration of H+in a solution.10.A solution of pH 7 is neutral; a pH value below 7 indicates acidity; pH above 7 indicatesalkalinity.11.The pH inside a cell and in culture media is stabilized with pH buffers.Organic Compounds (pp.59–73)1.Organic compounds always contain carbon and hydrogen.2.Carbon atoms form up to four bonds with other atoms.3.Organic compounds are mostly orentirely covalently bonded.Structure and Chemistry (pp.60–61)4.A chain of carbon atoms forms a carbon skeleton.5.Functional groups of atoms are responsible for most of the properties of organicmolecules.6.The letterRmay be used to denote the remainder of an organic molecule.7.Frequently encountered classes of molecules are R—OH (alcohols) and R—COOH(organic acids).8.Small organic molecules may combine into very large molecules called macromolecules.

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CHAPTER 2 Chemical Principles159.Monomers usually bond together by dehydration synthesis, or condensation reactions,that form water and a polymer.10.Organic molecules may be broken down by hydrolysis, a reaction involving the splittingof water molecules.Carbohydrates (pp.61–62)11.Carbohydrates are compounds consisting of atoms of carbon, hydrogen, and oxygen,with hydrogen and oxygen in a 2:1 ratio.12.Monosaccharides contain from three to seven carbon atoms.13.Isomers are two molecules with the same chemical formula but different structures andproperties—for example, glucose (C6H12O6) and fructose (C6H12O6).14.Monosaccharides may form disaccharides andpolysaccharides by dehydration synthesis.Lipids (pp.62–66)15.Lipids are a diverse group of compounds distinguished by their insolubility in water.16Simple lipids (fats) consist of a molecule of glycerol and three molecules of fatty acids.17.A saturated lipid has no double bonds between carbon atoms in the fatty acids; an unsatu-rated lipid has one or more double bonds. Saturated lipids have higher melting pointsthan unsaturated lipids.18.Phospholipids are complex lipids consisting of glycerol, two fatty acids, and a phosphategroup.19.Steroids have carbon ring structures; sterols have a functional hydroxyl group.Proteins (pp.66–70)20.Amino acids are the building blocks of proteins.21.Amino acids consist of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur.22.Twenty amino acids occur naturally in proteins.23.By linking amino acids, peptide bonds (formed by dehydration synthesis) allow theformation of polypeptide chains.24.Proteins have four levels of structure: primary (sequence of amino acids), secondary(helices or pleated), tertiary (overall three-dimensional structure of a polypeptide), andquaternary (two or more polypeptide chains).25.Conjugated proteins consist of amino acids combined with inorganic or other organiccompounds.Nucleic Acids (pp.70–72)26.Nucleic acids—DNA and RNA—are macromolecules consisting of repeatingnucleotides.27.A nucleotide is composed of a pentose, a phosphate group, and anitrogen-containingbase. A nucleoside is composed of a pentose and a nitrogen-containing base.28.A DNA nucleotide consists of deoxyribose (a pentose) and one of the following nitrogen-containing bases: thymine or cytosine (pyrimidines) or adenine or guanine (purines).

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16INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,GE, 13e29.DNA consists of two strands of nucleotides wound in a double helix. The strands are heldtogether by hydrogen bonds between purine and pyrimidine nucleotides: AT and GC.30.Genes consist of sequences of nucleotides.31.An RNA nucleotide consists of ribose (a pentose) and one of the following nitrogen-containing bases: cytosine, guanine, adenine, or uracil.Adenosine Triphosphate (ATP) (p.72)32.ATP stores chemical energy for various cellular activities.33.When the bond to ATP’s terminal phosphate group is hydrolyzed, energy is released.34.The energy from oxidation reactions is used to regenerate ATP from ADP and inorganicphosphate.The Loop1.Have students study Chapter 2 and use the Study Questions as a self-test.2.Have students study Chapter 2 and take a pretest for Chapter 5. Pretests can be adminis-tered individually during office hours,inopen laboratories,duringstudy sessions, oronline. Students who score at least 9 points out of 15 questions from the Chapter 2 TestBank show mastery. A student who does not achieve mastery can study and take asecond chapter test.3.Students with some chemistry but less than one year of college chemistry may find ituseful to have the last half of this chapter, “Important Biological Molecules,” whichbegins on page57, used as an introduction to Chapter 5, “Microbial Metabolism.”Exploring the MicrobiomeFeed Our IntestinalBacteria, Feed Ourselves: A Tale of Two StarchesThis chapter includes coverage of the role that carbohydrates play in the cell. The Exploringthe Microbiome segment suggeststhat specific carbohydrates in conjunction withcertainmicrobesproduce short-chain fatty acids, which may play a role in electrolyte absorption andprevention ofcolorectal cancer.Discussion questions:•Are there other (possibly) more efficient ways to obtain these short-chain fatty acids?•Does research performed on mice translate to people?•Could the same benefit of short-chain fatty acids be achieved bysimply consumingthose directly?•Relevant publication:Sivaprakasam S., Prasad P.D., and Singh N. (2016) Benefits ofshort-chain fatty acids and their receptors in inflammation and carcinogenesis.Pharmacology & Therapeutics, 164: 144-151.

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CHAPTER 2 Chemical Principles17AnswersFigure QuestionsFigureQuestionAnswer2.1What is the atomic number of this atom?Six. It is carbon.2.2What is an ionic bond?An ionic bondis anattractionbetweenatoms that have lost or gained electrons(ions).2.3What is a covalent bond?A covalent bond is formed by thesharingof electrons between atoms.2.4Which chemical elements are usuallyinvolved in hydrogen bonding?Hydrogen and oxygen or nitrogen.A hydrogen bondis an attraction betweena hydrogen atom that is covalently bondedto one oxygen or nitrogen atom andanother oxygen or nitrogen atom.2.5What happens during ionization?An atom or molecule gains or loseselectrons.2.6How do acids and bases differ?Acids dissociate into an anion and ahydrogen ion (H+). Bases dissociate intoa cation and a hydroxide ion (OH–).2.7At what pH are the concentrations ofH+and OHequal?72.8What is the difference between apolymer and a monomer?Apolymer consists of smaller moleculescalled monomers.2.9How do saturated and unsaturated fattyacids differ?Unsaturated lipids have one or moredouble bonds between carbon atoms.2.10Where are phospholipids found in cells?Membranes2.11Where are sterols found in cells?Membranes2.12What distinguishes one amino acid fromanother?Side groups called R groups.2.13Which isomer is always found inproteins?L-isomers2.14How are amino acids related to proteins?Proteins arecomposed of amino acids.2.15What property of a protein enables it tocarry out specific functions?The three-dimensional shape2.17How are DNA and RNA similar instructure?Both are polymers of nucleotides.2.18How is ATP similar to anucleotide inRNA? In DNA?Ribose is the sugar in the adenosinenucleotides in ATP and RNA. Deoxyri-bose is thesugar in the adenosine in DNA.

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18INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,GE, 13eReview1.Isotopes are atoms that have the same number of protons but different number ofneutrons.2.3.a.Ionicb.Single covalent bondc.Double covalent bondsd.Hydrogen bond4.a.False. It is an endergonic reaction, meaning that energy isdirected inward.b.False. Exchange reactions are part synthesis and part decomposition.5.The H+concentration of the broth is 10−6moles/liter, so its pH is −log10[10−6] =−(−6) =6. To maintain the pH of a medium, pH buffers are used.6.a.Lipidb.Proteinc.Carbohydrated.Nucleic acid7.a.Amino acidsb.Right to leftc.Left to right

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CHAPTER 2 Chemical Principles198.9.10.CelluloseMultiple Choice1.c6.c2.b7.a3.b8.a4.e9.b5.b10.cAnalysis1.a.Synthesis reactionb.H2CO3is an acid.2.ATP and DNA have 5-carbon sugars. ATP has ribose, and DNA has deoxyribose; ATPand DNA contain the purine, adenine.3.To maintain the proper fluidity, the percentage of unsaturated lipids decreases at thehigher temperature.4.These animals have cellulose-degrading bacteria in specialized structures in theirdigestive tracts.

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20INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,GE, 13eClinical Applicationsand Evaluation1.PHB is a fatty acid used as an energy storage molecule byRalstonia.2.T. ferrooxidanscan oxidize sulfur (“thio”) as well as iron (“ferro”). The oxidation ofsulfide in pyrite produces sulfuric acid, which dissolves the limestone. Gypsum forms ina subsequent exchange reaction.222242S3O2H O2SO4H−−+++→++2+34432CaCO+ 4H+ 2SO2CaSO+ 2H+ 2HCO−−→3.a.Amino acidb.Phenylalanine is not present in the baby’s blood.c.The phenylalanine from the aspartame (see Review question 7) will accumulate intheir bodies.4.Amphotericin B would not work against most bacteria because they lack sterols.Fungihave sterols and are generally susceptible to amphotericin B. Human cells have sterols.5.Methionine and cysteineCase Study:A Fussy BabyBackgroundThe alarm clock was set to go off at 6:00 am. Staring at it, Harold saw it change from 5:58to 5:59am. He reached over and turned it off, gently shook Naomi awake, then grabbed thevideo monitor to check on Amica. He was relieved to see his daughter was still asleep. Amicahad passed a rough night, waking up on multiple occasions. Two weeks earlier, Naomi hadnoticed small, irregular, white patches inside of Amica’s mouth. She had become increasinglyirritable, only breastfeeding or taking the bottle for short periods. Naomi experienced discom-fort while nursing Amica, so she purchased some over-the-counter ointment.Five days ago, the patches in Amica’s mouth returned and both Naomi and Amica weremore irritable. Amica kept on spitting out the pacifier that Harold gave her. At his wits’end,Harold searched the Internet for answers after he returned Amica to her crib for the fifth timethat night. He came across pictures of similar-looking patches in the mouths of babies. Couldit be thrush?It had been two weeks; it was definitely time to bring Amica to the pediatrician. Dr. KellyWarner examined a fussy Amica. Her vitals were normal: her temperature was 36.9°C(98.4°F), pulse 120 bpm (beats per minute), and blood pressure 75/55. However, Dr. Warnernoticed a reddish rash in Amica’s diaper area. Harold told her they were treating it with zincointment and that it had shown improvement. Harold also mentioned the increased discomfortthat Naomi had experienced during breastfeeding recently.“You are right, this is thrush,” said Dr. Warner. “Everybody has microbes in their mouth,including the organism that causes thrush. In healthy people the growth of the yeast,Candidaalbicansthat causes thrush is kept in check by other microbes living in the mouth.”“Also,” continued Dr. Warner, “milk is such a rich source of organic compounds such ascarbohydrates and proteins, the very nutrients that the yeast uses to grow.”

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CHAPTER 2 Chemical Principles21“So why did the microbes in Amica’s mouth not prevent this overgrowth?” asked Harold.“Is she sick?”“No, she is not sick. Infants just have an underdeveloped microbiome in their mouth. It takestime for the balance to be established. If Naomi experiences discomfort during breastfeeding,she probably has the yeast on her skin and it gets passed back and forth between Naomi andAmica. Both should be treated at the same time.”“Naomi has been using ointments” said Harold.“I know” said Dr. Warner. “She should stop for now. Most of the time thrush disappears onits own, but since you say it’s been going on for two weeks now, I will prescribe somethingand give you instructions for both Naomi and Amica so they can both get better.”“And what about the diaper rash?” asked Harold. “The diaper rash is caused by the samemicrobe. Make sure to keep the diaper area as dry as possible and wash your hands thorough-ly before and after diaper changes. You may use a wet wash cloth to wipe Amica’s tonguegently after feeding to remove excess milk.” replied the Dr. Warner.Questions1.Could the patches in Amica’s mouth, and Noami’s discomfort be related?2.What is the role of carbohydrates and proteins in cells?Answers1.Yes, the fungus that causes thrush can also cause irritation of the breast.2.Carbohydrates and proteins are nutrients. Carbohydratesarea source of energy,proteins provide amino acids.

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22CHAPTER3Observing Microorganismsthrough a MicroscopeGlobal EditionLearning ObjectivesCheck Your Understanding3-1List the units usedto measuremicroorganisms.How many nanometers is 10 μm?3-2Diagram the path of light through acompound microscope.Through what lenses does light pass in acompound microscope?3-3Definetotal magnificationandresolution.What does it mean when a microscope hasa resolution of 0.2 nm?3-4Identify a use for darkfield, phase-contrast,differential interference contrast, fluores-cence, confocal, two-photon, and scanningacoustic microscopy, and compare eachwith brightfield illumination.How are brightfield, darkfield, phase-contrast, and fluorescence microscopysimilar?3-5Explain how electron microscopy differsfrom light microscopy.Why do electron microscopes have greaterresolution than light microscopes?3-6Identify usesfor thetransmission electronmicroscope(TEM),scanning electronmicroscope(SEM), and scanned-probemicroscopes.For what is TEM used? SEM? Scanned-probe microscopy?3-7Differentiate an acidic dye from a basic dye.Why doesn’t a negative stain color a cell?3-8Explain the purpose of simple staining.Why is fixing necessary for most stainingprocedures?3-9List Gram stainsteps, and describe theappearance of gram-positive and gram-negative cells after each step.Why is the Gram stain so useful?3-10Compare and contrast the Gram stain andthe acid-fast stain.Which stain would be used to identifymicrobes in the generaMycobacteriumandNocardia?3-11Explain why each of the following is used:capsule stain, endospore stain, flagella stain.How do unstained endospores appear?Stained endospores?

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CHAPTER 3 Observing Microorganisms through a Microscope23New inThis Edition•Coverage of super-resolution light microscopy has been added.Chapter SummaryUnits of Measurement (p.78)1.Microorganisms are measured in micrometers, μm (106m), and in nanometers,nm (109m).Microscopy: The Instruments (pp.78–87)ASM2.1: The structure and function of microorganisms have beenrevealed by the use of microscopy (including bright field, phasecontrast, fluorescent, and electron).1.A simple microscope consists of onelens; a compound microscope has multiple lenses.Light Microscopy (pp.78–84)2.The most common microscope used in microbiology is the compound lightmicroscope (LM).3.The total magnification of an object is calculated by multiplying the magnification of theobjective lens by the magnification of the ocular lens.4.The compound light microscope uses visible light.5.The maximum resolution, or resolving power (the ability to distinguish two points) of acompound light microscope is 0.2μm; maximum magnification is1,500.6.Specimens are stained to increase the difference between the refractive indexes of thespecimen and the medium.7.Immersion oil is used with the oil immersion lens to reduce light loss between theslideand the lens.8.Brightfield illumination is used for stained smears.9.Unstained cells are more productively observed using darkfield, phase-contrast, or DICmicroscopy.10.The darkfield microscope shows a light silhouette of an organism against a darkbackground.It is most useful for detecting the presence of extremely small organisms.11.A phase-contrast microscope brings direct and reflected or diffracted light rays together(in phase) to form an image of the specimen on the ocular lens.It allows the detailedobservation of living organisms.12.The DIC microscope provides a colored, three-dimensional image ofliving cells.13.In fluorescence microscopy, specimens are first stained with fluorochromes and thenviewed through a compound microscope by using an ultraviolet light source. The micro-organisms appear as bright objects against a dark background.

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24INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,GE, 13e14.Fluorescence microscopy is used primarily in a diagnostic procedure called fluorescent-antibody (FA) technique, or immunofluorescence.15.In confocal microscopy, a specimen is stained with a fluorescent dye and illuminatedwith short-wavelength light.Two-Photon Microscopy (p.84)16.In TPM, a live specimen is stained with a fluorescent dye and illuminated withlong-wavelength light.Super-Resolution Light Microscopy (pp.84–85)17.Super-resolution light microscopy uses two lasers to excite fluorescent molecules.18.When a computer is used to process the images, two-dimensional and three-dimensionalimages of cells can be produced.Scanning Acoustic Microscopy (p.85)19.Scanning acoustic microscopy (SAM) is based on the interpretation of sound wavesthrough a specimen.20.It is used to study living cells attached to surfaces such as biofilms.Electron Microscopy (pp.85–87)21.Instead of light, a beam of electrons is used with an electron microscope.22.Instead of glass lenses, electromagnets control focus,illumination, and magnification.23.Thin sections of organisms can be seen in an electron micrograph produced using atransmission electron microscope (TEM). Magnification: 10,000–10,000,000.Resolving power: 10 pm.24.Three-dimensional views of the surfaces of whole microorganisms can be obtained witha scanning electron microscope (SEM). Magnification: 1,000–500,000.Resolution: 10 nm.Scanned-Probe Microscopy (p.87)25.Scanning tunnelingmicroscopy (STM) and atomic force microscopy (AFM) producethree-dimensional images of the surface of a molecule.Preparation of Specimens for Light Microscopy (pp.87–95)ASM 8.1: Properly prepare and view specimens for examination usingmicroscopy (bright field and, if possible, phase contrast).ASM 8.5: Use appropriate microbiological and molecular labequipment andmethods.Preparing Smears for Staining (pp.87–91)1.Staining means coloring a microorganism with a dye to make some structures morevisible.

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CHAPTER 3 Observing Microorganisms through a Microscope252.Fixing uses heat or alcohol to kill and attach microorganisms to a slide.3.A smear is a thin film of material used for microscopic examination.4.Bacteria are negatively charged, and the colored positive ion of a basic dye will stainbacterial cells.5.The colored negative ion of an acidic dye will stain the background of a bacterial smear;a negative stain is produced.Simple Stains (p.91)6.A simple stain is an aqueous or alcohol solution of a single basic dye.7.A mordant may beused to improve bonding between the stain and the specimen.Differential Stains (pp.91–92)8.Differential stains, such as the Gram stain and acid-fast stain, differentiate bacteriaaccording to their reactions to the stains.9.The Gram stain procedure uses a purple stain,iodine as a mordant, an alcoholdecolorizer, and a red counterstain.10.Gram-positive bacteriaremainpurple after the decolorization step; gram-negativebacteria do not,and appear pink from the counterstain.11.Acid-fast microbes, such as members of the generaMycobacteriumandNocardia, retaincarbolfuchsin after acid-alcohol decolorization and appear red; non-acid-fast microbestake up the methylene blue counterstain and appear blue.Special Stains (pp.92–95)12.Negative staining is used to make microbial capsules visible.13.The endospore stain and flagella stain are special stains that are used to visualize specificstructures in bacterial cells.The LoopChapter 3 should provide a good reference for laboratory exercises on microscopy andstaining. The test questions can be used as laboratory quizzes.Exploring the MicrobiomeObtaining a More Accurate Picture ofOurMicrobiotaThissegment explains how the microscopy techniques described in thischaptercan be usedto visualize the diversity of microbiota.Discussion questions:•How can microscopy results be interpreted correctly, ifgram-positive bacteriasometimes staingramnegative?•What are the possible reasons thatgram-positive bacteria staingramnegative?

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26INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,GE, 13e•Does the presence of certain bacteria mean that they play an important role in ourmicrobiota?•Knowing thatour assumptions about the predominant bacteria in the microbiota maynot be accurate, which other experiments should be performed?AnswersFigure QuestionsFigureQuestionAnswer3.1What is the total magnification of acompound light microscope with objectivelens magnification of 40and ocular lensof 10?4003.3Why is immersion oil necessary at 1,000but not with the lower power objective?The oil prevents refraction oflightaway from the specimen, because it hasa similar refraction index to the glass ofthe lens.3.4What are the advantages of brightfield,darkfield, and phase-contrast microscopy?Brightfield: Easy to see stained cellsquickly.Darkfield: Looking at the silhouette ofunstained cells.Phase-contrast: Looking at intracellularstructures in live, unstained cells.3.5Whyisa DIC microscope appear brightlycolored?Prisms split light into componentwavelengths.3.6Why won’t other bacteria fluoresce in theFTA-ABS test?The antibody is specific for a particularorganism.3.7What are the advantages of confocalmicroscopy?Images can be made into athree-dimensional view.3.8What are the differences between TPM andconfocal microscopy?TPM uses long wavelengths to illumi-nate the specimen. Confocal uses shortwavelengths to illuminate the specimen.3.9What is the advantage of super-resolutionmicroscopy?Improved resolution as the image isprepared 1 nm at a time.3.10What is the principal use of SAM?SAM is used to study living cellsattached to another surface, such ascancer cells, arterial plaque, andbacterial biofilms.3.11How do TEM and SEM images of thesame organism differ?TEM images are flat, while SEMimages are three-dimensional.3.12What is the principle employed in scanned-Electric current is used to detect surface

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CHAPTER 3 Observing Microorganisms through a Microscope27probe microscopy?structures.3.13How can the Gram reaction be useful inprescribing antibiotic treatment?Gram-positive bacteria are notnecessarily susceptible to the sameantibiotics as gram-negative bacteria.3.14Why isMycobacterium tuberculosiseasilyidentified by the acid-fast stain?Mycobacteriumis acid-fast, and normalmicrobiota are not acid-fast.3.15Of what value are capsules, endospores,and flagella to bacteria?Capsules: Adherence, protectionagainst phagocytes.Endospores: Survive adverse environ-ments.Flagella: Motility allows finding newfood source.Review1.a.10–6mb.nmc.103nm2.a.Compound light microscopeb.Darkfield microscopec.Phase-contrast microscoped.Fluorescencemicroscopee.Electron microscopef.Differential interference contrast microscope3.4.Ocular lens magnificationoil immersion lens magnification=total magnification ofspecimen10100=1,0005.a.1,500c.0.2 μme.Seeingthree-dimensional detailb.10,000,000d.10pm

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28INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,GE, 13e6.Alcohol wash disrupts the outer lipopolysaccharide layer of gram-negative bacteria,washing out the CV–I complex through the thin layer of peptidoglycan and making itcolorless to be couterstained pink or red with safranin. Without alcohol wash, the gramnegative will retain the purple color and would falsely appear to be gram positive.7.A simple stain is an aqueous or alcohol solution of a single basic dye. Methylene blue,carbolfuchsin, crystal violet, and safranin are a few commonly used simple stains.8.Staining makes it possible for a cell to be distinguished from its surroundings underbrightfield illumination, while in darkfield microscopy, staining is unnecessary as onlylight reflected by a specimen enters the objective lens, making the specimen visibleagainst a dark background without the presence of staining.9.a.Purpled.Purpleg.Colorlessb.Purplee.Purpleh.Redc.Purplef.Purple10.An acid-fast bacterium (Mycobacterium)Multiple Choice1.c6.e2.c7.d3.c8.b4.d9.a5.a10.bAnalysis1.The counterstain safranin can be omitted. Gram-positive bacteria will appear purple, andgram-negative bacteria will be colorless.2.You would be able to discern two objects when they are separated by 2 μm but not whenthey are separated by 0.2 μm or 200 nm because in these two cases (0.2 μm and 200 nm),the distance between the objects is less than the resolving power of the microscope.3.The high lipid content of acid-fast cell walls makes them impermeable to most stains.If the primary stain penetrates, the Gram stain decolorizer will not decolorize the cell.Therefore, acid-fast bacteria would be gram-positive if they could be Gram stained.TheGram reaction of non-acid-fast bacteria may be positive or negative, depending on thebacterial cell wall structure.4.Inclusions as well as endospores may not stain in a Gram stain. The endospore stain willidentify the unstained structure as an endospore.Clinical Applicationsand Evaluation1.Ehrlich observed thatmycobacteria could not be decolorized with acid-alcohol, so hereasoned that an acidic disinfectant would not be able to penetrate the cell wall.2.N. gonorrhoeaebacteria are gram-negative (red) diplococci, often found in the largehuman cells (phagocytes).3.The cells are gram-positive and possess endospores.

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30INSTRUCTOR'S GUIDE FORMICROBIOLOGY: AN INTRODUCTION,GE, 13eCase Study:Preparing Bacterial SmearsBackgroundMason was a bit nervous. After all, today was the first day at his new job. Granted, it was justan internship, but he thought of it as his first official job. Since he would be working in amicrobiological diagnostics lab, everything he did would be important. Even if he was justassigned to clean the benches in the laboratory, if he didn’t do it right, he might be responsi-ble for contaminating cultures from patient samples. He had been shown around the lab lastweek, completed all the safety training, and he had spent the whole weekend reviewing hisMicrobiology notes.Once he was settled, the laboratory manager told him that his first assignment would be toprepare bacterial smears from patient samples. There were three groups of samples, Group 1contained sputum samples from patients tentatively diagnosed with pneumonia; Group 2contained sputum samples from patients tentatively diagnosed with tuberculosis; and Group 3contained samples of cerebrospinal fluid from patients tentatively diagnosed with meningitis.The laboratory manager mentioned that Mason should prepare bacterial smear for each of thesamples. A Gram stain and capsule stain were to be performed on the samples in Groups 1and 3, and an acid-fast stain was ordered on the samples inGroup 2.“Remember,” said the laboratory manager, “you will prepare two separate bacterial smearsfor the samples in Groups 1 and 3. One for the Gram stain, and one for the capsule stain. Donot heat-fix the bacterial smears for the capsule stain. And be extra careful with thosesamples. You should treat those smears very gently.”“Sure, I remember how to do this,” thought Mason, “but why do I have to be extra careful?”Questions1.What is the purpose of heat-fixing bacterial smears?2.Why does Mason need to be extra careful with the smears prepared for performing acapsule stain?3.What is an acid-fast stain used for? Why is it necessary to perform a different type ofstain than the Gram stain or the capsule stain in suspected cases of tuberculosis?Answers1.Heat-fixing kills the bacteria and adheres them to the glass slide so that they do not washoff easily.2.Since the slide will not be heat-fixed, the bacteria will be alive (and therefore potentiallyinfectious) and can wash off easily.3.An acid-fast stain is used to stain bacteria belonging to the genusMycobacterium, whichhave a thick layer of the waxy lipid mycolic acid outside their cell wall. Mycolic aciddoes not take up the dyes used in the Gram stain. Tuberculosis is caused by a bacteriumbelonging to the genusMycobacterium, so an acid-fast stain is necessary.

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30CHAPTER4Functional Anatomy ofProkaryotic and Eukaryotic CellsGlobal EditionLearning ObjectivesCheck Your Understanding4-1Comparethecell structure of prokaryotesand eukaryotes.What is the main feature that distinguishesprokaryotes from eukaryotes?4-2Identify the three basic shapes ofbacteria.Howcanyou be able to identify streptococciwitha microscope?4-3Describe the structure and function of theglycocalyx.Why are bacterial capsules medicallyimportant?4-4Differentiate flagella, axial filaments,fimbriae, and pili.How do bacteria move?4-5Compare and contrast the cell walls ofgram-positive bacteria, gram-negativebacteria, acid-fast bacteria, archaea, andmycoplasmas.Why are drugs that target cell wall synthesisuseful?4-6Compare and contrast archaea and myco-plasmas.Why are mycoplasmas resistant to antibioticsthat interfere with cell wall synthesis?4-7Differentiateprotoplast,spheroplast,andL form.How do protoplasts differ from L forms?4-8Describe the structure, chemistry, andfunctions of the prokaryotic plasmamembrane.Which agents can cause injury to the bacterialplasma membrane?4-9Definesimple diffusion,facilitated diffu-sion,osmosis,active transport, andgrouptranslocation.How are simple diffusion and facilitateddiffusion similar? How are they different?4-10Identify the functions of the nucleoid andribosomes.Where is the DNA located in a prokaryoticcell?4-11Identify the functions of four inclusions.What is the general function of inclusions?4-12Describe the functions of endospores,sporulation, and endospore germination.Under what conditions do endospores form?

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