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CHAPTER SUMMARY

Microbes in Our Lives (p. 2)

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. Some microorganisms live in humans and other animals and 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. 2–6)

Nomenclature (p. 2)

1. In a nomenclature system designed by Carolus Linnaeus (1735), each living organism is assigned two names.

2.The two names consist of a genus and a specific epithet, both of which are underlined or italicized.

Types of Microorganisms (pp. 3–6)

Bacteria (pp. 3–4)3. Bacteria are unicellular organisms. Because they have no nucleus, the cells are

described as prokaryotic.4. The three major basic shapes of bacteria are bacillus, coccus, and spiral.5. Most bacteria have a peptidoglycan cell wall; they divide by binary fission, and they

may possess flagella.6. Bacteria can use a wide range of chemical substances for their nutrition.

Archaea (p. 4)7. Archaea consist of prokaryotic cells; they lack peptidoglycan in their cell walls.8. Archaea include methanogens, extreme halophiles, and extreme thermophiles.

Fungi (p. 4)9. Fungi (mushrooms, molds, and yeasts) have eukaryotic cells (cells with a true

nucleus). Most fungi are multicellular. Have chitin cell wall.10. Fungi obtain nutrients by absorbing organic material from their environment.

Protozoa (pp. 4, 6)11. Protozoa are unicellular eukaryotes.12. Protozoa obtain nourishment by absorption or ingestion through specialized

structures. No cell wall, change shape easily (ameba).

Copyright © 2010 Pearson Education, Inc.

Algae (p. 6)13. Algae are unicellular or multicellular eukaryotes that obtain nourishment by

photosynthesis. Have other plant like properties too. 14. Algae produce oxygen and carbohydrates that are used by other organisms.But have

little medical importance, only one related to disease.

Viruses (p. 6)15. Viruses are noncellular entities that are parasites of cells.16. Viruses consist of a nucleic acid core (DNA or RNA) surrounded by a protein coat.

An envelope may surround the coat.

Multicellular Animal Parasites (p. 6)17. The principal groups of multicellular animal parasites are flatworms and

roundworms, collectively called helminths.18. The microscopic stages in the life cycle of helminths are identified by traditional

microbiological procedures.domain Single/

multi cell

Cell wall

food Genetic material

Living?

bacteria prokaryote

single Y photosynthesis or nutrients

DNA Y

algae eukaryote single or multi

Y photosynthesis DNA Y Little medical relevance; important for ecosystem.

fungi eukaryote single or multi

Y chitin

nutrients DNA Y plant like

protozoa eukaryote single N nutrients DNA Y amebaVirus (viroid, prion)

Not living no cell nocell parasitic; Can’t get food on its own.

DNA or RNA

N

Classification of Microorganisms (p. 6)

19. All organisms are classified into Bacteria, Archaea, and Eukarya. Eukarya include protists, fungi, plants, and animals.

A Brief History of Microbiology (pp. 6–16)

The First Observations (p. 7)

1. Robert Hooke observed that cork was composed of “little boxes”; he introduced the term cell (1665).


2. Hooke’s observations laid the groundwork for development of the cell theory, the concept that all living things are composed of cells.

3.Anton van Leeuwenhoek, using a simple microscope, was the first to observe microorganisms (1673).

The Debate over Spontaneous Generation (p. 8)

4. Until the mid-1880s, many people believed in spontaneous generation, the idea that living organisms could arise from nonliving matter.

5. Francesco Redi demonstrated that maggots appear on decaying meat only when flies are able to lay eggs on the meat (1668).

6. John Needham claimed that microorganisms could arise spontaneously from heated nutrient broth (1745).

7. Lazzaro Spallanzani repeated Needham’s experiments and suggested that Needham’s results were due to microorganisms in the air entering his broth (1765).

8. Rudolf Virchow introduced the concept of biogenesis: living cells can arise only from preexisting cells (1858).

9. Louis Pasteur demonstrated that microorganisms are in the air everywhere and offered proof of biogenesis (1861).

10. Pasteur’s discoveries led to the development of aseptic techniques used in laboratory and medical procedures to prevent contamination by microorganisms.

11. John Tyndall arranged sealed flasks of boiled infusion in air tight box. After dusk settled and carefully opened box, the liquid remain sterile.

The Golden Age of Microbiology (pp. 9–11)

11. The science of microbiology advanced rapidly between 1857 and 1914.

Fermentation and Pasteurization (p. 9)12. Pasteur found that yeast ferment sugars to alcohol and that bacteria can oxidize the

alcohol to acetic acid, making the wine oily and sour. Later Pasteur’s contribution includes the silk worm industry, idetified 3 separate diseases caused by 3 microorganisms.

13. A heating process called pasteurization is used to kill bacteria in some alcoholic beverages and milk.

The Germ Theory of Disease (pp. 9, 11)14. Agostino Bassi (1835) and Pasteur (1865) showed a causal relationship between

microorganisms and disease.15. Agnaz Semmelweis recognized a connection between autopsies and puereral fever

due to not washing hands between the two activities. Joseph Lister introduced the use of a disinfectant to clean surgical wounds in order to control infections in humans (1860s).


16. Robert Koch proved that microorganisms cause disease. He used a sequence of procedures, now called Koch’s postulates (1876), that are used today to prove that a particular microorganism causes a particular disease.

1). The causative agent must be found in every case of the disease.2). The disease organism must be isolated and cultured in vitro.3). Inoculationof the same culture to healthy, susceptable animal must induce the

same disease.4). The disease organism must be isolated again from the inoculated animal.

Vaccination (p. 11)17. In a vaccination, immunity (resistance to a particular disease) is conferred by

inoculation with a vaccine.18. In 1798, Edward Jenner demonstrated that inoculation with cowpox material provides

humans with immunity to smallpox.19. About 1880, Pasteur discovered that avirulent bacteria could be used as a vaccine for

fowl cholera; he coined the word vaccine.20. Modern vaccines are prepared from living avirulent microorganisms or killed

pathogens, from isolated components of pathogens, and by recombinant DNA techniques.

21. Elie Metchinikoff discovered cellular immunity, phagocytes.

The Birth of Modern Chemotherapy: Dreams of a “Magic Bullet” (pp. 12–13)

21. Chemotherapy is the chemical treatment of a disease.22. Two types of chemotherapeutic agents are synthetic drugs (chemically prepared in the

laboratory) and antibiotics (substances produced naturally by bacteria and fungi to inhibit the growth of other microorganisms).

23. Paul Ehrlich introduced an arsenic-containing chemical called salvarsan to treat syphilis (1910).

24. Alexander Fleming observed that the Penicillium fungus inhibited the growth of a bacterial culture. He named the active ingredient penicillin (1928).

25. Penicillin has been used clinically as an antibiotic since the 1940s.26. Researchers are tackling the problem of drug-resistant microbes.

Modern Developments in Microbiology (pp. 13–16)

27. Bacteriology is the study of bacteria, mycology is the study of fungi, and parasitology is the study of parasitic protozoa and worms.

28. Microbiologists are using genomics, the study of all of an organism’s genes, to classify bacteria, fungi, and protozoa.

29. The study of AIDS, analysis of the action of interferons, and the development of new vaccines are among the current research interests in immunology.

30. New techniques in molecular biology and electron microscopy have provided tools for advancing our knowledge of virology.


31. The development of recombinant DNA technology has helped advance all areas of microbiology.

Microbes and Human Welfare (pp. 16–18)

1. Microorganisms degrade dead plants and animals and recycle chemical elements to be used 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 insect

pests. 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. Using recombinant 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 genes

into human cells.8. Genetically modified bacteria are used in agriculture to protect plants from frost and

insects and to improve the shelf life of produce.

Microbes and Human Disease (pp. 18–21)

1. Everyone has microorganisms in and on the body; these make up the normal microbiota, or flora.

2. The disease-producing properties of a species of microbe and the host’s resistance are important factors in determining whether a person will contract a disease.

3. Bacterial communities that form slimy layers on surfaces are called biofilms.4. An infectious disease is one in which pathogens invade a susceptible host.5. An emerging infectious disease (EID) is a new or changing disease showing an

increase in incidence in the recent past or a potential to increase in the near future.


Units of Measurement (p. 55)

1. The standard unit of length is the meter (m).2. Microorganisms are measured in micrometers, µm (10–6 m), and in nanometers, nm

(10–9 m). 1m = 103 mm = 106 m =109 nm = 1012 pm = 1015Å

Microscopy: The Instruments (p. 55)

1. A simple microscope consists of one lens; a compound microscope has multiple lenses.

Light Microscopy (pp. 56, 58–62)

Compound Light Microscopy (pp. 56, 58–59)2. The most common microscope used in microbiology is the compound light

microscope (LM).3. The total magnification of an object is calculated by multiplying the magnification of

the objective 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

a compound light microscope is 0.2 µm; maximum magnification is 2000x.6. Specimens are stained to increase the difference between the refractive indexes of the

specimen and the medium.7. Immersion oil is used with the oil immersion lens to reduce light loss between the

slide and the lens. Refraction is the bending of light as it passes through from one medium to another of different density. The index of refraction is a measured of the speed at which light pases through the material. Immersion oil has the same index of refraction as glass, not air.

8. Brightfield illumination is used for stained smears or sections.9. Unstained cells are more productively observed using darkfield, phase-contrast, or

DIC(Differential Interference Contrast, Nomarski) microscopy.

Darkfield Microscopy (p. 59)10. The darkfield microscope shows a light silhouette of an organism against a dark

background. Light does not transmitted directly through the specimen, rather, it reflect off the specimen at an angle.

11. It is most useful for detecting the presence of extremely small organisms.

Phase-Contrast Microscopy (pp. 59–60)12. 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. Has a special condemser and objective lens that accentuate the differences in the refractive index of various structures within the organism.

13. It allows the detailed observation of living organisms.


Differential Interference Contrast (DIC) Microscopy (p. 60)14. The DIC microscope provides a colored, three-dimensional image of the object being

observed. A refined phase contrast scope.15. It allows detailed observations of living cells.

Fluorescence Microscopy (pp. 61–62)16. In fluorescence microscopy, specimens are first stained with fluorochromes and then

viewed through a compound microscope by using an ultraviolet light source.17. The microorganisms appear as bright objects against a dark background.18. Fluorescence microscopy is used primarily in a diagnostic procedure called

fluorescent-antibody (FA) technique, or immunofluorescence.

Confocal Microscopy (p. 62)19. In confocal microscopy, a specimen is stained with a fluorescent dye and illuminated

with short-wavelength light.20. Using a computer to process the images, two-dimensional and three-dimensional

images of cells can be produced.

Two-Photon Microscopy (p. 62)

21. In TPM, a live specimen is stained with a fluorescent dye and illuminated with long-wavelength light.

Scanning Acoustic Microscopy (p. 63)

22. Scanning acoustic microscopy (SAM) is based on the interpretation of sound waves through a specimen.

23. It is used to study living cells attached to surfaces such as cancer cells, artery plaque, and biofilms.

Electron Microscopy (pp. 63–65)

24. Instead of light, a beam of electrons is used with an electron microscope. Shorter the wave length, bettr the resolution.

25. Instead of glass lenses, electromagnets control focus, illumination, and magnification.26. Thin sections of organisms can be seen in an electron micrograph produced using a

transmission electron microscope (TEM). Magnification: 10,000–100,000x. Resolving power: 2.5 nm.

27. Three-dimensional views of the surfaces of whole microorganisms can be obtained with a scanning electron microscope (SEM). Magnification: 1000–10,000x. Resolving power: 20 nm. It usually used with the freeze – fracture technique, producing a natural surface. Metal can be sparayed on.

Scanned-Probe Microscopy (p. 65)


28. Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) produce three-dimensional images of the surface of a molecule.

Preparation of Specimens for Light Microscopy (pp. 68–72)

Preparing Smears for Staining (pp. 68–69)

1. Staining means coloring a microorganism with a dye to make some structures more visible.

2. 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 stain

bacterial 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. 69)

6. A simple stain is an aqueous or alcohol solution of a single basic dye.7. It is used to make cellular shapes and arrangements visible.8. A mordant may be used to improve bonding between the stain and the specimen.

Differential Stains (pp. 69–71)

9. Differential stains, such as the Gram stain and acid-fast stain, differentiate bacteria according to their reactions to the stains.

10. The Gram stain (after Danish physician Hans gram) procedure uses a purple stain (crystal violet), iodine as a mordant, 95% alcohol or ethanol-acetone solution decolorizer, and a red safranin counterstain.

11. Gram-positive bacteria retain the purple stain after the decolorization step; gram-negative bacteria do not and thus appear pink from the counterstain.

12. Acid-fast microbes, such as members of the genera Mycobacterium and Nocardia, retain carbolfuchsin after acid-alcohol (3% HCl in 95% ethanol) decolorization and appear red; non–acid-fast microbes take up the methylene blue counterstain and appear blue.

13. A good way to check Gram reaction is to use 3% KOH solution. G+ cells will be lysed.

Special Stains (pp. 71–72)

13. Negative staining is used to make microbial capsules visible. Background is filled with stain such as Indian Ink or nigrosin. A second stain, crystal violet or methelene blue, shows up the cell inside the capsular material.

14. The endospore stain and flagella stain are special stains that color only certain parts of bacteria. Schaeffer-Fulton spore stain makes spore easy to visualize. Applying


malachite green with heat and then counterstaining with safranin, the endospore will be green against pink cell.

THE PROKARYOTIC CELL (pp. 77–98)

1. Bacteria are unicellular, and most of them multiply by binary fission.2. Bacterial species are differentiated by morphology, chemical composition, nutritional

requirements, biochemical activities, and source of energy.

The Size, Shape, and Arrangement of Bacterial Cells (pp. 77–79)

1. Most bacteria are 0.2 to 2.0 µm in diameter and 2 to 8 µm in length.2. The three basic bacterial shapes are coccus (spherical), bacillus (rod-shaped), and

spiral (twisted).3. Pleomorphic bacteria can assume several shapes.

Structures External to the Cell Wall (pp. 79–84)

Glycocalyx (pp. 79–81)

1. The glycocalyx (capsule, slime layer, or extracellular polysaccharide) is a gelatinous polysaccharide and/or polypeptide covering.

2. Capsules may protect pathogens from phagocytosis.3. Capsules enable adherence to surfaces, prevent desiccation, and may provide

nutrients.4. Cell removed of cell wall is called protoplast.

Flagella (pp. 81–82)

4. Flagella are relatively long filamentous appendages consisting of a filament, hook, and basal body.

5. Prokaryotic flagella rotate to push the cell.6. Motile bacteria exhibit taxis; positive taxis is movement toward an attractant, and

negative taxis is movement away from a repellent.7.Flagellar (H) protein is an antigen.

Axial Filaments (pp. 82–83)

8. Spiral cells that move by means of an axial filament (endoflagellum) are called spirochetes.

9.Axial filaments are similar to flagella, except that they wrap around the cell.


Fimbriae and Pili (pp. 83–84)

10. Fimbriae help cells adhere to surfaces.11. Pili are involved in twitching motility and DNA transfer.

The Cell Wall (pp. 84-89)

Composition and Characteristics (pp. 85-87)

1. The cell wall surrounds the plasma membrane and protects the cell from changes in water pressure.

2. The bacterial cell wall consists of peptidoglycan, a polymer consisting of N-acetylglucosamine (gluNAc), N-acetylmuramic acid (mur NAc) and short chains of amino acids.

3. Penicillin interferes with peptidoglycan synthesis.4. Gram-positive cell walls consist of many layers of peptidoglycan and also contain

teichoic acids wich consists of glycerol, phosphate, sugar alcohol ribitol.5. Gram-negative bacteria have a lipopolysaccharide-lipoprotein-phospholipid outer

membrane surrounding a thin peptidoglycan layer.6. The outer membrane protects the cell from phagocytosis and from penicillin,

lysozyme, and other chemicals.7. Porins are proteins that permit small molecules to pass through the outer membrane;

specific channel proteins allow other molecules to move through the outer membrane.8.The lipopolysaccharide component of the outer membrane consists of sugars (O

polysaccharides), which function as antigens, and lipid A, which is an endotoxin.

Cell Walls and the Gram Stain Mechanism (p. 87)

9. The crystal violet–iodine complex combines with peptidoglycan.10. The decolorizer removes the lipid outer membrane of gram-negative bacteria and

washes out the crystal violet.

Atypical Cell Walls (pp. 87–88)

11. Mycoplasma is a bacterial genus that naturally lacks cell walls.12. Archaea have pseudomurein; they lack peptidoglycan.13. Acid-fast cell walls have a layer of mycolic acid outside a thin peptidoglycan layer.

Damage to the Cell Wall (pp. 88–89)

14. In the presence of lysozyme, gram-positive cell walls are destroyed, and the remaining cellular contents are referred to as a protoplast.

15. In the presence of lysozyme, gram-negative cell walls are not completely destroyed, and the remaining cellular contents are referred to as a spheroplast.

16. L forms are gram-positive or gram-negative bacteria that do not make a cell wall.


17. Antibiotics such as penicillin interfere with cell wall synthesis.

Structures Internal to the Cell Wall (pp. 89–98)

The Plasma (Cytoplasmic) Membrane (pp. 89–91)

1. The plasma membrane encloses the cytoplasm and is a lipid bilayer with peripheral and integral proteins (the fluid mosaic model).

2. The plasma membrane is selectively permeable.3. Plasma membranes contain enzymes for metabolic reactions, such as nutrient

breakdown, energy production, and photosynthesis.4. Mesosomes, irregular infoldings of the plasma membrane, are artifacts, not true cell

structures.5. Plasma membranes can be destroyed by alcohols and polymyxins.

The Movement of Materials across Membranes (pp. 91–94)6. Movement across the membrane may be by passive processes, in which materials

move from areas of higher to lower concentration and no energy is expended by the cell.

7. In simple diffusion, molecules and ions move until equilibrium is reached.8. In facilitated diffusion, substances are transported by transporter proteins across

membranes from areas of high to low concentration.9. Osmosis is the movement of water from areas of high to low concentration across a

selectively permeable membrane until equilibrium is reached.10. In active transport, materials move from areas of low to high concentration by

transporter proteins, and the cell must expend energy.11. In group translocation, energy is expended to modify chemicals and transport them

across the membrane.

Cytoplasm (p. 94)

12. Cytoplasm is the fluid component inside the plasma membrane.13. The cytoplasm is mostly water, with inorganic and organic molecules, DNA,

ribosomes, and inclusions.

The Nucleoid (pp. 94–95)

14. The nucleoid contains the DNA of the bacterial chromosome.15. Bacteria can also contain plasmids, which are circular, extrachromosomal DNA

molecules.

Ribosomes (p. 95)

16. The cytoplasm of a prokaryote contains numerous 70S ribosomes; ribosomes consist of rRNA and protein.


17. Protein synthesis occurs at ribosomes; it can be inhibited by certain antibiotics.

Inclusions (pp. 95–96)

18. Inclusions are reserve deposits found in prokaryotic and eukaryotic cells.19. Among the inclusions found in bacteria are metachromatic granules (inorganic

phosphate), polysaccharide granules (usually glycogen or starch), lipid inclusions, sulfur granules, carboxysomes (ribulose 1,5-diphosphate carboxylase), magnetosomes (Fe3O4), and gas vacuoles.

Endospores (pp. 96–98)

20. Endospores are resting structures formed by some bacteria; they allow survival during adverse environmental conditions.

21. The process of endospore formation is called sporulation; the return of an endospore to its vegetative state is called germination.


Review Ountline:

1. Main contribution of the following scientists.EhrlichJennerKochPasteurLeeuwenhoekListerFlemingSemmelweis

2. Term: Microbial ecology Normal microbiotaMicrobial physiology PathogenImmunology ChemotherapyVirology VaccineBacterology Antibiotics / penicillinParasitology

3. Recognize scientific name. e.g. Strptococcus pyogenes; Genus – specific epithet

4. The 3 domains of living organisms: ___________, _____________, ______________.

5. Which domains are single celled?

6. Features of viruses? Features of bacteria, algae, protozoa, fungi and helminths/ arthropods?

7. How was Spontaneous Generation disapproved?

8. Basis of using microbe to control insects?

9. What is biofilm?

10. Unit conversion of meter system

11. Optical path of compound light microscope; effect of wave length? Occular lens?


12. Light properties: resolusion, magnification, wave length, reflection, refraction, transmission, absorption, index of refraction

13. Reagents: Crystal violetMethylene blueIodineEthanol-acetoneAcid-alcoholCarbolfuchsinSafraninIndian inkNegrosinSchaaeffer-Fulton stain

14. MordantDecolorizerSimple StainCounter stain

15. To determine cell sizeTo determine cell shapeTo see endosporesTo determine Gram reaction

16. Microscope types:Compound lightDarkfieldPhase contrastFluorescentConfucalDIC (Nomarsky)Electron transmissionElectron scanningScanning Tunneling (STM)Atomic Force (AFM)Acoustic (AEM)


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