Microbiology

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Microbiology Study Guide 2nd Edition 11/6/2018

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Acknowledgements We would like to thank the authors for their patience, support, and expertise in contributing to this study guide; and for the editors for their invaluable efforts in reading and editing the text. We would also like to thank those at Achieve whose hard work and dedication to fulfilling this project did not go unnoticed. Lastly, we would like to thank the Achieve students who have contributed to the growth of these materials over the years.

Copyright © 2018 by Achieve All rights reserved. This book or any portion thereof may not be reproduced or used in any manner whatsoever without the express written permission of the publisher except for the use of brief quotations in a book review. Printed in the United States of America First Printing, 2015 Achieve PO Box 10188 #29831 Newark, NJ 07101-3188 Tel: 888.900.8380 Visit the Achieve website at http://www.achievetestprep.com/student

Microbiology Study Guide

Table of Contents Chapter 1: Introduction to Microbiology ..................................................................................................7 1.1 Early History of Microbiology........................................................................................................................... 7 Discovery of Microorganisms...............................................................................................................................................................7 Spontaneous Generation.........................................................................................................................................................................7 Germ Theory of Disease...........................................................................................................................................................................7 Discovery of Immunity.............................................................................................................................................................................8 Discovery of Viruses ..................................................................................................................................................................................9 Development of Chemotherapeutic Agents (Chemicals, Medications, and Drugs)...................................................9 1.2 Naming and Classifying Microorganisms....................................................................................................... 9 Nomenclature................................................................................................................................................................................................9 Place of Microorganisms in the World.......................................................................................................................................... 10 Differences between Prokaryotes and Eukaryotes ................................................................................................................ 10 Prokaryotes (Prokaryotae): Bacteria, Cyanobacteria, and Archaeobacteria............................................................ 10 Eukaryotes (Eukaryotae): Protozoa, Algae, and Fungi......................................................................................................... 10 1.3 Microbial Laboratory Techniques .................................................................................................................11 Microscopy .................................................................................................................................................................................................. 11 Stain Procedures....................................................................................................................................................................................... 11 Media Preparation and Growth ........................................................................................................................................................ 11 Categories..................................................................................................................................................................................................... 12 Pure Culture and Aseptic Techniques ........................................................................................................................................... 12 1.4 Chapter One Practice Exam.............................................................................................................................13 Chapter 2: Biology of Microorganisms ................................................................................................... 15 2.1 Anatomy................................................................................................................................................................15 Prokaryotic Cells....................................................................................................................................................................................... 15 Eukaryotic Cells: Protozoa, Algae, and Fungi (Yeasts and Molds).................................................................................. 17 2.2 Growth and Nutrition of Microorganisms ...................................................................................................20 Patterns of Nutrition .............................................................................................................................................................................. 20 Stages in Normal Growth Curve ....................................................................................................................................................... 20 Essential Nutrients.................................................................................................................................................................................. 20 Organisms and Energy Pathways .................................................................................................................................................... 20 Requirements for Growth.................................................................................................................................................................... 21 Cultivation.................................................................................................................................................................................................... 23 Dynamics of Populations...................................................................................................................................................................... 24 2.3 Metabolism: Basic Methods of Metabolism and Energy Conversion....................................................26 Enzymes ........................................................................................................................................................................................................ 26 Photosynthetic vs. Chemosynthetic Metabolism..................................................................................................................... 28 Cellular Respiration ................................................................................................................................................................................ 28 Photosynthesis .......................................................................................................................................................................................... 30 2.4 Genetics.................................................................................................................................................................31 Variations of Cells and Viruses.......................................................................................................................................................... 31

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©2018 of 132 Mutations...................................................................................................................................................................................................... 31 Recombination........................................................................................................................................................................................... 32 Gene Manipulation .................................................................................................................................................................................. 33 2.5 Viruses...................................................................................................................................................................35 Structure....................................................................................................................................................................................................... 35 Multiplication of Viruses ...................................................................................................................................................................... 36 Effects of Viruses on Cells.................................................................................................................................................................... 37 2.6 Chapter Two Practice Exam ............................................................................................................................39 Chapter 3: Control of Microorganisms ................................................................................................... 41 3.1 Principles of Microbial Control ......................................................................................................................41 Factors Influencing the Success of Control Methods............................................................................................................. 41 General Methods of Control................................................................................................................................................................ 42 Physical Methods of Control............................................................................................................................................................... 43 Chemical Methods of Control............................................................................................................................................................. 45 3.2 Chemotherapeutic Agents and Antibiotics..................................................................................................46 Chemotherapeutic Agents ................................................................................................................................................................... 46 Antibiotics (Penicillin and Others).................................................................................................................................................. 47 3.3 Chapter Three Practice Exam .........................................................................................................................49 Chapter 4: Disease, Resistance, and the Immune System ................................................................. 51 4.1 The Disease Process ..........................................................................................................................................51 Host-Parasite Relationships ............................................................................................................................................................... 51 Progress of Disease ................................................................................................................................................................................. 52 Clinical and Subclinical Disease........................................................................................................................................................ 53 Types of Diseases ..................................................................................................................................................................................... 53 Establishment of Disease ..................................................................................................................................................................... 54 4.2 Nonspecific Resistance to Disease.................................................................................................................55 Mechanical and Chemical Factors ................................................................................................................................................... 55 Phagocytosis ............................................................................................................................................................................................... 56 Inflammation.............................................................................................................................................................................................. 57 Individual, Species, and Racial Immunities ................................................................................................................................ 57 4.3 Principles of Immunology................................................................................................................................58 Antigens ........................................................................................................................................................................................................ 58 The Immune System............................................................................................................................................................................... 58 Types of Immunity................................................................................................................................................................................... 62 Detecting Antibodies with Laboratory Tests............................................................................................................................. 63 4.4 Disorders of the Immune System...................................................................................................................64 Hypersensitivity Reactions ................................................................................................................................................................. 64 Type I Anaphylactic Hypersensitivity ........................................................................................................................................... 64 Type II Cytotoxic Hypersensitivity.................................................................................................................................................. 64 Type III Immune Complex Hypersensitivity.............................................................................................................................. 65 Type IV Cellular Hypersensitivity.................................................................................................................................................... 65 Immune Deficiency Disease................................................................................................................................................................ 65 4.5 Chapter Four Practice Exam............................................................................................................................67 Achieve Page 4

Microbiology Study Guide

Chapter 5: Biology of Infectious Diseases.............................................................................................. 69 5.1 Respiratory Tract Diseases .............................................................................................................................69 Bacterial Diseases .................................................................................................................................................................................... 69 Viral Diseases ............................................................................................................................................................................................. 71 Fungal Diseases......................................................................................................................................................................................... 73 Protozoan Diseases ................................................................................................................................................................................. 73 5.2 Gastrointestinal Tract Diseases and Intoxications...................................................................................74 Bacterial Diseases and Intoxications ............................................................................................................................................. 74 Viral Diseases ............................................................................................................................................................................................. 76 Protozoan Diseases ................................................................................................................................................................................. 77 5.3 Urogenital Tract Diseases................................................................................................................................77 Bacterial Diseases .................................................................................................................................................................................... 77 Viral Diseases ............................................................................................................................................................................................. 78 Fungal Diseases......................................................................................................................................................................................... 79 Protozoan Diseases ................................................................................................................................................................................. 79 5.4 Skin and Wound Diseases ................................................................................................................................79 Bacterial Diseases .................................................................................................................................................................................... 79 Viral Diseases ............................................................................................................................................................................................. 80 Fungal and Parasitic Disease s ............................................................................................................................................................ 81 5.5 Blood Diseases ....................................................................................................................................................82 Bacterial Diseases .................................................................................................................................................................................... 82 Viral Diseases ............................................................................................................................................................................................. 83 Protozoan Diseases ................................................................................................................................................................................. 85 5.6 Acquired Immunodeficiency Syndrome (AIDS).........................................................................................85 5.7 Chapter Five Practice Exam.............................................................................................................................87 Chapter 6: Environmental, Food, and Industrial Microbiology ....................................................... 89 6.1 Environmental (Ecological) Microbiology: .................................................................................................89 Terrestrial Environment (Soils)....................................................................................................................................................... 89 Aquatic Environment ............................................................................................................................................................................. 92 Water Quality Tests................................................................................................................................................................................. 94 6.2 Food Microbiology .............................................................................................................................................95 Foods from Microorganisms .............................................................................................................................................................. 95 Food Spoilage by Microorganisms .................................................................................................................................................. 96 Food Preservation ................................................................................................................................................................................... 98 6.3 Industrial Microbiology................................................................................................................................. 100 Fermentations......................................................................................................................................................................................... 100 Microbial Products ............................................................................................................................................................................... 101 Insecticides and Leaching Agents................................................................................................................................................. 101 6.4 Chapter Six Practice Exam............................................................................................................................ 103 Microbiology Final Exam..........................................................................................................................105 Answer Keys.................................................................................................................................................131

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Chapter 1: Introduction to Microbiology Objectives 1. Know the history and evolution of microorganisms. 2. Understand germ theory of disease and ways to combat infectious diseases. 3. Identify different categories of microorganisms. 4. Explain microbial laboratory techniques. 1.1 Early History of Microbiology

Discovery of Microorganisms A long time ago, invisible living creatures were thought to exist. They were held responsible for disease long before they were observed. In the mid-1600s, Robert Hooke was the first person to observe strands of fungi. After a few decades, Antony van Leeuwenhoek observed microscopic organisms and named them animalcules. He was the first one who discovered and provided accurate descriptions of protozoa, bacteria, and fungi. He constructed over 400 microscopes as well. After he died in 1723, the theory of spontaneous generation was debated by many scientists. Spontaneous Generation Many scientists prior to the second half of the 1800s believed in spontaneous generation, claiming that living organisms could develop from nonliving or decomposing matter. Many people believed that animals were born of the dirt in the ground, and flies were created by the manure from which they fed. There were some scientists that disagreed with this theory for centuries before it was rejected, and in contrast, many scientists who believed in it and attempted to prove the theory. Some prominent scientists include: • Francesco Redi (1626-1697) challenged this concept by showing that maggots on decaying meat came from fly eggs deposited on the meat, and not from the meat itself. • John Needham (1713-1781) showed that mutton broth boiled in flasks and then sealed could still develop microorganisms, which supported the theory of spontaneous generation. • Lazzaro Spallanzani (1729-1799) showed that flasks sealed and then boiled had no growth of microorganisms, and he proposed that air carried germs to the culture medium. He also commented that external air might be needed to support the growth of animals already in the medium; the latter concept was appealing to supporters of spontaneous generation. Germ Theory of Disease Several events led to the development and proof that microbes cause disease, otherwise known as germ theory. Some of the theories propounded by early scientists include: • Hieronymus Fracastorius (Girolamo Fracastoro) wrote "On Contagion" in 1546, which is the first known discussion of the phenomenon of contagious infection.

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• Rudolf Virchow was a German scientist who first proposed the theory of biogenesis, which is the claim that cells arise from other cells. However, he was unable to prove his theory. • John Tyndall (1820-1893) demonstrated that dust did carry microbes and that if dust was absent, the broth remained sterile, even if it was directly exposed to air. Tyndall also provided evidence for the existence of heat-resistant forms of bacteria. • Agostino Bassi de Lodi (1835) showed that fungus was responsible for the disease affecting silkworms. This discovery marked the first microorganism to be identified responsible for a disease. • Louis Pasteur (1822-1895) played a major role in proving germ theory. He set up an experiment involving beef broth and open-ended, long neck flasks. All the flasks were filled with beef broth and boiled. After boiling, some were left open to air and others were sealed. Those that were sealed did not have microbes, while those left open contained microbes. He proved that the air contained microorganisms. He is credited for forming the basis for aseptic techniques. Pasture is also the founder of pasteurization, which heats a liquid to a specific temperature that will kill unwanted microbes and render the liquid safe to consume. This is a milestone accomplishment for the field of microbiology and allowed a direct link between microbes and the potential for causing disease. In addition, Pasteur identified a protozoan in 1865 that was responsible for silkworm disease. This was important at that time because silkworms were dying and the silk industry in Europe was suffering. Not only did he identify the protozoan, but he developed a method to determine which worms were afflicted. • Ignaz Semmelweis (1818-1865), a noted Hungarian physician, showed that doctors in Vienna hospitals were responsible for spreading puerperal (childbed) fever while delivering babies. He introduced infection control in the 1840s by having the doctors under his supervisionwash their hands between patient contacts. • In the 1860s Joseph Lister (1827-1912), an English surgeon, introduced antiseptics in surgery through the use of carbolic acid to clean and kill the bacteria on surgical instruments, wounds, and dressings. His success reduced surgical mortality due to bacterial infection and resulted in this practice being adopted by other surgeons. • Robert Koch (1843-1910) was a German bacteriologist. He was the first to cultivate the rod- shaped anthrax bacteria, Bacillus Anthrais, outside the body using blood serum (1876) and subsequently injected these bacteria into healthy cattle, resulting in the disease state. He subsequently published “Koch's Postulates” in 1884, which formed the critical test method for proof that a microorganism is the cause of a disease, although it should be noted that there are a few diseases that fall outside the postulates. “Koch's Postulates” states: o The pathogen must be present in every case of the disease. o The pathogen must be isolated and cultured in vitro. o The disease must be reproduced when a pure culture of the pathogen is inoculated into a susceptible host. o The pathogen must be recoverable from the experimentally-infected host. Discovery of Immunity Smallpox was endemic in China by 1000 B.C. With the understanding that survivors of smallpox were

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subsequently immune from re-infection, prevention was undertaken through the practice of variolation , which is an induction of a mild form of the disease. This involved the inhalation and sniffing of dried crusts from a smallpox lesion. Later this practice changed to inoculation through the use of the pus from a lesion scratched into the skin. In 1796 after hearing from a milkmaid that she could not contract smallpox because she had already had cowpox, Edward Jenner took scrapings from cowpox lesions then used these scrapings when scratching the arm of a young child. A small bump appeared in a few days, followed by the mild illness of cowpox. He then directly exposed that same boy to smallpox, with the result of no smallpox disease development, thus confirming vaccination. Discovery of Viruses The very first virus discovered is credited to the St. Petersburg Academy of Science in 1892 by Dmitri Iwanowsk (1864-1920), a Russian botanist. While studying mosaic tobacco disease, he found that the agent causing the disease was small enough to pass through a ceramic filter small enough to trap bacteria. This is generally accepted as the beginning of virology. During the 1940s the electron microscope was invented, which allowed microbiologists a more in-depth observation of viruses. Development of Chemotherapeutic Agents (Chemicals, Medications, and Drugs) Once microbiologists were knowledgeable on the relationship between microbes and disease, scientists wanted to find substances to destroy the microbes that caused disease. Chemotherapy is the treatment of diseases with the use of chemical substances. Antibiotics and synthetic drugs are chemotherapy agents. Antibiotics are derived from naturally existing bacteria and fungi, while synthetic drugs are developed as chemicals in a laboratory. The first chemotherapy drugs were quinine, a bark extract used to treat malaria and salvarsan, and were developed in 1910 by Paul Ehrlich. Salvarsan contained arsenic and was used to treat syphilis. 1.2 Naming and Classifying Microorganisms Nomenclature The system of nomenclature (naming) for organisms used today was established in 1735 by Carlos Linnaeus. Scientific names are in Latin. Scientific nomenclature assigns two names: the Genus is the first name and is always capitalized; the specific epithet (species) is the second name and is not capitalized. The organism is referred to by both names and is always underlined or italicized . Once the scientific name has been mentioned completely, it can then be abbreviated with the initial of the first name followed by the second name. Scientific names can describe an organism, honor a researcher, or identify the habitat of a species. For example, Staphylococcus aurens is the scientific name for a bacterium found on skin. Staphylo describes the clustered arrangement of cells; coccus means that they are shaped like spheres. The specific epithet (second name), aurens is Latin for golden, which is the color of many colonies of these

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bacteria. Once the full name, Staphylococcus aurens, as S. aurens when used later. Place of Microorganisms in the World The major groups of microorganisms are bacteria, fungi, protozoa, and viruses. All microorganisms are very small . Most microbes are only one cell. Viruses do not have cells and are dead outside a living host. Viruses become alive inside a host. All microbes range in size from small viruses (20 nm) to protozoans (>5mm). Differences between Prokaryotes and Eukaryotes Prokaryotic organisms (before nucleus) have no true nucleus and no internal membrane-bound structures (organelles). This group includes bacteria and archaea. Eukaryotic organisms (true nucleus) do have true nucleus and do have internal membrane-bound structures (organelles). This group includes organisms like protistans, fungi, animals (including helminths or worms), and plants. Prokaryotes (Prokaryotae): Bacteria, Cyanobacteria, and Archaeobacteria Bacteria (single-bacterium) are single celled with spherical, rod, or spiral shapes. These organisms have no nucleus and no membrane-enclosed intracellular structures (no organelles). They have a cell wall that contains a protein-carbohydrate complex. Bacteria replicate by a process known as binary fusion, in which they divide into two equal cells. Many of these organisms absorb nutrients from their environment, while some make their own nutrients using photosynthesis or other synthetic processes. Widely distributed in nature, bacteria can be stationary or mobile and certain species can cause human and animal diseases (pathogenic bacteria). Cyanobacteria is a type of bacteria that get their energy from photosynthesis. They are called “cyanobacteria” because of their color (cyan blue). Archaeobacteria are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon (sometimes spelled “archeon”). They have no cell nucleus or any other membrane-bound organelles within their cells. They also have no cell wall and no membrane-bound organelles. Eukaryotes (Eukaryotae): Protozoa, Algae, and Fungi Protozoa are a diverse group of single-cell eukaryotic organisms, many of which are motile. Protozoa are defined as single-cell protists with animal like movement. They move through the use of flagella, cilia, or pseudo-pods. Many are parasites but they can live as single entities. Simple algae (protophyta) are single-celled protists (eukaryotic organisms) that have plant-like behavior (get their energy from photosynthesis). Simple algae grow in fish tanks, pools, and ponds. Fungi are unicellular or multi-cellular (yeasts are unicellular, molds are multi-cellular) heterotrophs (depending on outside energy sources). They are scavenger; they live off dead matter and thus, decompose it. Viruses are dead on the outside of host cells and are alive on the inside of host cells. A virus is a small has been mentioned, it can then be abbreviated

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infectious agent that can replicate only inside the living cells of other organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants, and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898, about 5000 viruses have been described in detail, although there are millions of different types. Viruses are found in almost every ecosystem on Earth and are the most abundant type of biological entity. The study of viruses is known as virology , a sub- specialty of microbiology. 1.3 Microbial Laboratory Techniques Microscopy Microscopy is the use of microscopes to view samples and objects that cannot be seen with the unaided eye. The three branches of microscopy are optical, electron, and scanning probe. Optical and electron microscopy involve the diffraction, reflection, or refraction of electromagnetic radiation/electron beams interacting with the specimen, and the subsequent collection of this scattered radiation or another signal in order to create an image. Scanning probe microscopy involves the interaction of a scanning probe with the surface of the object of interest. Stain Procedures Because microbial cytoplasm is usually transparent, it is necessary to stain microorganisms before they can be viewed with the light microscope. In some cases, staining is unnecessary, such as when microorganisms are very large or when motility is to be studied. A drop of the microorganisms can be placed directly on the slide and observed. A preparation such as this is called a wet mount. A wet mount can also be prepared by placing a drop of culture on a cover-slip (a glass cover for a slide) and then inverting it over a hollowed-out slide. This procedure is called the hanging drop. In preparation for staining, a small sample of microorganisms is placed on a slide and permitted to air dry. The smear is heat fixed by quickly passing it over a flame. Heat fixing kills the organisms, makes them adhere to the slide, and permits them to accept the stain. Media Preparation and Growth Microorganisms need nutrients, a source of energy, and certain environmental conditions in order to grow and reproduce. In the environment, microbes have adapted to the habitats most suitable for their needs, in the laboratory, however, these requirements must be met by a culture medium. This is basically an aqueous solution to which all the necessary nutrients have been added. Depending on the type and combination of nutrients, different categories of media can be made.

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Categories Complex media are rich in nutrients and contain water soluble extracts of plant or animal tissue (e.g., enzymatically digested animal proteins such as peptone and tryptone). Often, glucose is added to serve as the main carbon and energy source. The combination of extracts and sugar creates a medium that is rich inminerals and organic nutrients, but since the exact composition is unknown, themedium is called complex. Defined media are media composed of pure ingredients in carefully measured concentrations dissolved in double distilled water, that is, the exact chemical composition of the medium is known. Typically, they contain a simple sugar as the carbon and energy source, an inorganic nitrogen source, various mineral salts, and if necessary, growth factors (purified amino acids, vitamins, purines, and pyrimidines). Selective/differential media are media based on either of the two categories above supplemented with growth-promoting or growth-inhibiting additives. The additives may be species or organism selective [e.g., a specific substrate, or an inhibitor, such as cyclohexamide, which inhibits all eucaryotic growth and is typically used to prevent fungal growth in mixed cultures). Media Purpose Complex Grow most heterotrophic organisms Defined Grow specific heterotrophs and are often mandatory for chemoautotrophs, photoautotrophs, and microbiological assays Selective Suppress unwanted microbes or encourage desired microbes Differential Distinguish colonies of specific microbes from others Enrichment Similar to selective media but designed to increase the numbers of desired microorganisms to a detectable level without stimulating the rest of the bacterial population Reducing Growth of obligate anaerobes The mixture of necessary nutrients can be used as a liquidmedium or a solidifying agent can be added. “Agar agar” is a natural polysaccharide produced by marine algae and is the most commonly used solidifying agent added to media (end concentration is usually 1.5% w/v). If hydrolysis of the agar is suspected, a silica gel is used as a replacement solidifying agent. Pure Culture and Aseptic Techniques Before inoculation with the desired microorganisms, microbiological media and all materials coming into contact with it must be sterile. During any subsequent handling of the bacterial cultures, unwanted or contaminant organisms must be excluded employing aseptic techniques. Sterilization implies the complete destruction of all microorganisms, including spores, which is accomplished by the use of heat, chemicals, radiation, and filtration.

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1.4 Chapter One Practice Exam 1. Which of the following bacterium is commonly found on skin? a. Staphylococcus aurens b. Acetobacter aceti c. Actinobacillus lignieresii d. Mycoplasma cynos 2. Who propounded the theory of pasteurization, under which the unwanted microbes are killed from a liquid when heated to a specific temperature? a. Agostino Bassi de Lodi b. Louis Pasteur c. Ignaz Semmelweis d. Joseph Lister 3. Which of the following organisms is not a type of eukaryotic organism? a. Fungus b. 4. Who introduced antiseptics in surgery through the use of carbolic acid to clean and kill bacteria on surgical instruments, wounds, and dressings? a. 5. Which of the following statements is false in regard to the assumptions made in the publication “Koch Postulates” propounded by Robert Koch? a. The pathogen must be present in every case of the disease b. The pathogen must be isolated and cultured in vitro c. The disease must be reproduced when a pure culture of the pathogen is inoculated into a susceptible host d. The pathogen must not be recoverable from the experimentally-infected host Helminths c. Protistans d. Bacteria Joseph Lister b. Louis Pasteur c. John Tyndall d. Lazzaro Spallanzani

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6. Which among the following organisms have no true nucleus and no internal membrane-bound structures? a. Plants b. Worms c. Archaea d. Fungi 7. Which of the following statements is not true about cyanobacteria? a. They get the energy from photosynthesis b. They are single cell eukaryotic organisms c. They have no nucleus d. They are cyan blue in color 8. Which branch of microscopy involves the interaction of a scanning probe with the surface of the object of interest? a. Optical b. Electron c. Scanning probe d. All of these 9. In which of the following cases is undertaking stain procedures not necessary? a. When microorganisms are very large b. When motility is not to be studied c. When microorganisms are very small d. When observation cannot be made directly by dropping a drop of microorganism on the slide 10. Which of the following procedures implies the complete destruction of all microorganisms, including spores, and is accomplished by the use of heat, chemicals, radiation, and filtration? a. Agar agar b. Sterilization c. Treatment with defined media Pasteurization Answer Keys found on page 131

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Chapter 2: Biology of Microorganisms

Objectives 1. Identify the anatomy of different types of cells. 2. Understand the basis of nutrients and growth of microorganisms. 3. Analyze the mechanism of metabolism and conversion of energy. 4. Discuss genetics in regard to variations in population, mutations, recombination, and gene manipulation. 5. Explain the structure and multiplication of viruses and their effects on cells. 2.1 Anatomy Prokaryotic Cells Prokaryotic cells are those cells that do not have a cell nucleus or any membrane-bound organelles, such as mitochondria. There are basically two types of prokaryotic cells: bacteria and archaea. Bacteria Gross morphology: size, shape, and arrangement • Prokaryotes are among the smallest of all organisms; they are usually from 0.5 to 2.0 mm in diameter and have a large surface to volume ratio; they typically display three basic shapes: o Spherical (coccus) o Rod-like (bacillus) o Spiral (vibrio, spirillum, or spirochete) • They can be found in distinctive arrangements: o Division in one plane produces cells in pairs (indicated by the prefix diplo-) o In chains (strepto-) o Division in two planes produces cells in tetrads o Division in three planes produces sarcinae o Random division planes produce grape-like clusters (staphylo-) Overview of structure: • Structurally, prokaryotic cells consist of the following: o Capsule: The outer slimy covering of the cell, often known as slime capsule, helps to protect the cell from outside microorganisms and helps maintain the moist habitat so that the bacteria can stay in their colonies. o Cell membrane o Internal cytoplasm

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o o Cell wall: The semi-rigid cell wall maintains the characteristic shape of the prokaryotic cell and prevents the cell from bursting when fluids flow into the cell. Its single most important component is peptidoglycan. § Other components include the outer membrane and the periplasmic space. Certain properties of cell walls result in different staining reactions. On the basis of these reactions, you can distinguish between gram-positive, gram-negative, and acid-fast bacteria. Gram-positive bacteria have a thick peptidoglycan layer and teichoic acid polymers. Gram-negative bacteria have a thin peptidoglycan layer and an outer bilayer membrane with endotoxins. The cell membrane, otherwise known as the plasma membrane, is a living membrane that forms the boundary between a cell and its environment. It is selectively permeable and is made up of seven lipid proteins. The internal structure found in bacterial cells includes: • Ribosomes: Serve as sites for protein synthesis • Nuclear region or nucleoid: Consists mainly of DNA (usually contains a single, long, continuous, and frequently circularly arranged thread of double stranded DNA called the bacterial chromosome); has some RNA and protein associated with it (plasmids- extrachromosomal genetic elements that are not connected to the main bacterial chromosome and replicate independently of chromosomal DNA) • Internal membrane systems: Sometimes known as chromatophores or mesosomes • Inclusions: Small bodies in the cytoplasm • Endospores: Help the organism survive The external structure includes: • Flagella: Help bacteria to move in processes like chemotaxis or phototaxis • Axial filaments: Cause rigid spirochetes to rotate like a corkscrew • Pili: Used to attach bacteria to surfaces • Glycocalyx substances: Include capsules and slime layers The bacterial endospore is a special, resistant, dormant structure formed by some bacteria, which enables them to resist harsh environmental conditions. Endospore formation (sporulation) normally commences when growth ceases because of lack of nutrients; it is a complex, multistage process. Transformation of dormant endospores into active vegetative cells is also a complex, multistage process that includes activation (preparation) of the endospore, germination (breaking of the endospore’s dormant state), and outgrowth (emergence of the new vegetative cell). Cyanobacteria Cyanobacteria are the aquatic, gram-negative oxygenic phototrophic bacteria in which the Variety of external structures

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deoxyribonucleic acid (DNA) is not delimited by the nuclear membrane. The DNA, in fact, has been dispersed to some magnitude throughout the cell. Cyanobacteria are omnipresent and are generally present in all kind of habitats. Chlorophyll a, P-carotene, Antheraxanthin, Aphanicin, Aphanizophyll, Flavacin, Lutein, Myxoxanthophyll, Oscilloxanthin, Zeaxanthin, Allophycocyanin, Phycocyanin, and Phycoerythrin are the major pigments found in these microorganisms. The storage products in cyanobacteria are cyanophycean starch and protein and they do not have flagella. They may be unicellular, colonial, and filamentous. Eukaryotic Cells: Protozoa, Algae, and Fungi (Yeasts and Molds) Cell Structure Eukaryotic cells are generally larger and more complex than prokaryotic cells. They also contain a variety of cellular bodies called organelles . The organelles function in the activities of the cell and are compartments for localizing metabolic function. Microscopic protozoa, unicellular algae, and fungi have eukaryotic cells. Plasma membrane is similar to the cell membranes of prokaryotic cells but is less versatile and contains a greater variety of lipids. The internal structure includes: • Cytoplasm: Semi-fluid substance consisting mainly of water • Cell nucleus: Contains DNA, some RNA, and some proteins • Mitochondria: Powerhouses of eukaryotic cells • Chloroplasts: Carry out photosynthesis • Ribosomes: Provide sites for protein synthesis • Endoplasmic reticulum: Forms the vesicles that transport lipids and proteins to the Golgi apparatus • Lysosomes: Contain digestive enzymes that digest the substances in vacuoles • Peroxisomes: Oxidize amino acids in animal cells and fats in plant cells • Vacuoles: Stores materials to be used for energy • Cytoskeleton: Supports and gives rigidity and shape to the cell The external structure includes: • Flagella: Helps cells to move • Cilia: Allows organisms to move rapidly • Pseudopodia: Helps cells move and ingests nutrients

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Microbiology Study Guide

Types of Eukaryotes Fungi A fungus is a member of a large group of eukaryotic organisms that includes microorganisms, such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria. One major difference is that fungal cells have cell walls that contain chitin, unlike the cell walls of plants, which contain cellulose. The growth of fungi as hyphae on or in solid substrates or as single cells in water environments is adapted for the efficient extraction of nutrients because these growth forms have high surface area to volume ratios. Hyphae (fungi “feet”) are specifically adapted for growth on solid surfaces and to invade substrates and tissues. Most fungi grow as hyphae, which are cylindrical, thread-like structures 2–10 µm in diameter and up to several centimeters in length. Hyphae grow at their tips (apices); new hyphae are typically formed by emergence of new tips along existing hyphae by a process called branching, or occasionally growing hyphal tips bifurcate (fork) giving rise to two parallel-growing hyphae. The combination of apical growth and branching/forking leads to the development of a mycelium, an interconnected network of hyphae. Fungal reproduction is complex, reflecting the differences in lifestyles and genetic makeup within this kingdom of organisms. It is estimated that one-third of all fungi reproduce by different modes of propagation; for example, reproduction may occur in two well-differentiated stages within the life cycle of a species, the teleomorph and the anamorph. Environmental conditions trigger genetically determined developmental states that lead to the creation of specialized structures for sexual or asexual reproduction. These structures aid reproduction by efficiently dispersing spores or spore- containing propagules. Asexual reproduction via vegetative spores (conidia) or through mycelial fragmentation is common. Sexual reproduction with meiosis exists in all fungi. Algae Algae are a large and diverse group of simple, typically autotrophic (make their own food) organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and “simple” because their tissues are not organized into the many distinct organs found in land plants. The largest and most complex marine forms are called seaweeds. Some species of algae form symbiotic relationships with other organisms. In these symbioses, the algae supply photosynthates (organic substances) to the host organism, providing protection to the algal cells. The host organism derives some or all of its energy requirements from the algae. Examples are lichens, coral reefs, and sea sponges. Almost all forms of algae have chloroplasts. These contain chlorophylls a and b, giving them a bright green color (as well as the accessory pigments beta carotene and xanthophylls), and have stacked thylakoids. All green algae have mitochondria with flat cristae. When present, flagella are typically anchored by a cross-shaped system of microtubules and fibrous strands, but these are absent among the higher plants and charophytes, which instead have a raft of microtubules, known as the spline. Flagella are

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