Microcheck 313

Both commercial and backyard composting reduce the need for large landfills to dispose of solid waste. What are the advantages and disadvantages of landfills List the steps in successful composting. Developing plants that can take up and concentrate heavy metal pollutants in soil water is an active field of research. Would this approach effectively remove polluting metals from the environment Nester-Anderson-Roberts I V. Applied Microbiology I 31. Environmental I I The McGraw-Hill Microbiology,...

Microcheck

A prokaryotic species can be grouped as a psychrophile, psychrotroph, mesophile, thermophile, or hyperthermophile, according to its optimum temperature for growth. A species can also be grouped according to its oxygen requirements as an obligate aerobe, obligate anaerobe, facultative anaerobe, microaerophile, or aerotolerant anaerobe. Most species are neutrophiles and grow best near neutral pH acidophiles prefer acidic conditions, and alkalophiles grow best in alkaline conditions. All organisms...

Chemoorganoheterotrophs

Chemoorganoheterotrophs, commonly referred to as chemo-heterotrophs or chemoorganotrophs, use organic compounds for energy and as a carbon source. They are by far the most common group associated with humans and other animals. Some play beneficial roles such as providing a source of vitamin K in the gut, whereas others cause disease. Chapter 4 Dynamics of Prokaryotic Growth PERSPECTIVE 4.1 Can Prokaryotes Live on only Rocks and Water Prokaryotes have been isolated from diverse environments that...

Photoheterotrophs

Photoheterotrophs use the energy of sunlight and derive their carbon from organic compounds. Some are facultative in their nutritional capabilities. For example, some members of a group of bacteria called the purple nonsulfur bacteria can grow anaer-obically using light as an energy source and organic compounds as a carbon source (photoheterotrophs). They can also grow aerobically in the dark using organic sources of carbon and energy (chemoheterotrophs). purple nonsulfur bacteria, p. 277

Co2

Organic compounds (sugars, amino acids, etc.) amounts of these trace elements are found in most natural environments, including water. Some bacteria cannot synthesize some of their cell constituents, such as amino acids, vitamins, purines, and pyrimidines, from the major elements. Consequently, these organisms can only grow in environments where such compounds are available. Those low molecular weight compounds that must be provided to a particular bacterium are called growth factors. purines,...

Info

A plasmid that can replicate in E. coli and Pseudomonas is most likely a an. 10. The frequency of transfer of an F' DNA molecule by conjugation is closest to the frequency of transfer of. A. chromosomal genes by conjugation. B. an F plasmid by conjugation. C. an F plasmid by transformation. D. an F plasmid by transduction. E. an R plasmid by DNA transformation. 1. Some bacteria are more resistant to UV light than other bacteria. Discuss two reasons why this might be the case. What experiments...

Prevention and Treatment

Suspected cases of bacterial conjunctivitis are removed from school or day care settings for diagnosis and start of treatment. General preventive measures include handwashing, and avoidance of rubbing or touching the eyes and sharing towels. Use of pacifiers beyond the age of two years is associated with a substantial increase in otitis media. Viral infections and other conditions that cause inflammation of the nasal mucosa play a role in some cases. Nasal allergies and exposure to air...

Anaerobic Chemotrophs

For approximately the first 1.5 billion years that prokaryotes inhabited earth, the atmosphere was anoxic, or devoid of O2. In the anaerobic environment, some early chemotrophs probably used a pathway of anaerobic respiration, employing electron acceptors such as carbon dioxide or elemental sulfur, which were plentiful in the environment. Others may have used fermentation, passing the electrons to an organic molecule such as pyruvate. Table ll.l Prokaryotes Notable for Their Environmental...

Immunodeficiency Disorders

The immunologic disorders discussed up to now can be viewed as resulting from the overreaction of the body's immune systems. By contrast, in immunodeficiencies, the body is incapable of making or sustaining an adequate immune response. There are two basic types of immunodeficiency diseases primary, or congenital and secondary, or acquired. Primary immunodeficiency can be inborn as the result of a genetic defect or can result from developmental abnormalities. Secondary immunodeficiency can be...

Colony Blots and Southern Blots

The heart of both a colony blot and a Southern blot is the use of a probe to locate a specific nucleotide sequence. The probe is a single-stranded piece of nucleic acid that has been tagged, or labeled, with a detectable marker such as a radioactive isotope, a fluorescent dye, or biotin the probe is complementary to either of the two strands being detected. The DNA of the specimen being examined is affixed to a solid surface such as a nylon membrane and treated with an alkaline solution to...

Anatomy and Physiology

Microorganisms that colonize the respiratory system enter an environment quite different than the one faced by skin organisms. The dark caverns and tortuous passages of the respiratory system are relatively hot and humid, and the atmosphere contains less oxygen and more carbon dioxide than occurs in air. The eyes and the nose are the two gateways, or portals of entry, to the respiratory system. They are more than entrances respiratory infections often first establish themselves there and then...

Daily Life

Washing and scrubbing with soaps and detergents achieves routine control of undesirable microorganisms and viruses. In fact, simple handwashing with plain soap and water is considered the single most important step in preventing the spread of many infectious diseases. Plain soap itself generally does not destroy many organisms it simply aids in the mechanical removal of transient microbes, including most pathogens, as well as dirt, organic material, and cells of the outermost layer of skin....

Epidemiological Studies

Epidemiologists investigate a disease outbreak to determine the causative agent as well as its reservoir and route of transmission, so as to recommend ways to minimize the spread. They are concerned with emerging diseases such as that caused by Escherichia coli O157 H7, and also with diseases that have been recognized for centuries, such as tuberculosis and cholera. The studies that epidemiologists conduct are in many ways similar to criminal investigations. After a disease outbreak,...

Causative Agent

Gonorrhea is caused by Neisseria gonorrhoeae, the gonococcus, a Gram-negative diplococcus that can be cultivated on choco Figure 25.8 Appearance of Neisseria gonorrhoeae in Pus from the Urethra Figure 25.8 Appearance of Neisseria gonorrhoeae in Pus from the Urethra Figure 25.9 Electron Micrograph of Neisseria gonorrhoeae Showing Pili Figure 25.9 Electron Micrograph of Neisseria gonorrhoeae Showing Pili late agar medium. The organisms are typically found on and within the leukocytes in urethral...

Induced Mutations

Mutants are essential for studying and understanding most aspects of genetics. Consequently, geneticists spend much of their time isolating mutants. One reason why bacteria represent an excellent experimental system for genetic studies and why more is Figure 8.3 Transposition Detected by Color Changes Variegation in color observed in the kernels of corn is caused by the insertion of transposable elements into genes involved in the synthesis of different pigments, thereby altering the synthesis...

Chemical Mutagens

Any chemical treatment that alters the hydrogen-bonding properties of a purine or pyrimidine base already in the DNA will increase the frequency of mutations as the DNA replicates. Chemical Modification of Purines and Pyrimidines One powerful mutagen that modifies purines and pyrimidines in DNA is nitrous acid (HNO2). This chemical primarily converts amino ( NH2) to keto (C O) groups for example, converting cytosine to uracil. Uracil then pairs with adenine rather than guanine when the DNA is...

Serology

The proteins and polysaccharides that make up a bacterium are sometimes characteristic enough to be considered identifying markers. The most useful of these are the molecules that make up surface structures including the cell wall, glycocalyx, flagella, and pili. For example, some species of Streptococcus contain a unique carbohydrate molecule as part of their cell wall that can be used to distinguish them from other species. These carbohydrates, as well as any distinct proteins or polysaccha-...

Causative Agent And Immune Response Of Poliomyelitis

Quantifying Antigen-Antibody Reactions 1. Active immunity occurs naturally in response to infections or other natural exposure to antigens, and artificially in response to vaccination. 1. Passive immunity occurs naturally during pregnancy and through breast feeding, and artificially by transfer of preformed antibodies, as in immune serum globulin and hyperimmune globulin. 17.2 Vaccines and Immunization Procedures 1. A vaccine is a preparation of a disease-causing agent or its products used to...

Microcheck 211

Antimicrobials are chemotherapeutic agents that are effective in treating microbial infections. Antibiotics are antimicrobial chemicals naturally produced by particular microorganisms. How is the microbe that makes penicillin different from the one that makes streptomycin Define and contrast the terms chemotherapeutic agent antimicrobial, and antibiotic. How might Streptomycesgriseus cells protect themselv from the effects of streptomycin Figure 21.1 Family Tree of Penicillins All of the...

Gases

Production of gases can be monitored in several ways. A method used in clinical labs employs a fluorescent molecule to detect bacteria growing in blood taken from patients who are suspected of having a bloodstream infection. The slight Figure 4.16 Measuring Turbidity with a Spectrophotometer (a)The cloudiness, or turbidity, of the liquid in the tube on the left is proportional to the concentration of cells. (b)The percentage of light that reaches the detector is inversely proportional to the...

Immunofluorescence Tests

Fluorescent dyes such as fluorescein or rhodamine can be attached to known specific antibodies, which are then used to detect the presence of an antigen in serum or microorganisms in a sample. There are two basic versions of these quick and sensitive tests. In this test, the microorganism to be tested is fixed to a slide. Known antibodies labeled with fluorescein are added, the mixture is incubated, and the slide is washed. Antibody that binds to the microorganism will not wash away. The slide...

Future Challenges

Ouite likely, poliomyelitis will be among the next ancient scourges to follow smallpox down the road to eradication. However, with smallpox, for a variety of political and scientific reasons, the causative virus still exists many years after the last naturally acquired case of the disease. Will it be any easier to rid the world of the polioviruses after the last case of poliomyelitis occurs Dramatic progress toward polio eradication has mainly been accomplished using immunization days when the...

Symptoms

Streptococcal pharyngitis typically is characterized by redness of the throat, with patches of adhering pus and scattered tiny hemorrhages, and fever. The lymph nodes in the neck are enlarged and tender. Abdominal pain or headache may be prominent in older children and young adults. Not usually present are red, weepy eyes, cough, or runny nose. Most patients with streptococcal sore throat recover spontaneously after about a week. In fact, many infected people have only mild symptoms or no...

Microcheck 224

Chickenpox, measles, and rubella can be controlled by vaccines. Viral diseases that may only inconvenience a pregnant woman can be disastrous to her fetus. A viral infection acquired in childhood can remain latent for years only to reactivate in a different form. One group of viruses causes benign skin tumors. What important diagnosis sign is often present in the mouth of measles (rubeola) victims What is the epidemiological significance of shingles Why is it a good idea to immunize little boys...

Cheese Yogurt and Other Fermented Milk Products

In a cow's udder, milk is sterile, but it rapidly becomes contaminated with a variety of microorganisms during milking and handling. Various species of lactic acid bacteria commonly reside on the udder and are inevitably introduced into the milk. If the milk is not refrigerated, these bacteria readily ferment lactose, the predominant sugar in milk, producing lactic acid. The removal of the primary carbohydrate as a nutrient source, combined with Table 32.1 Foods Produced Using Lactic Acid...

A 03 B 05 C 07 D 09 E

Which of the following is often added to wine to inhibit growth of the natural microbial population of grapes 10. In the brewing process, the sugar and nutrient extract obtained by soaking germinated grain in warm water is called 1. A small cheese-manufacturing company in Wisconsin is looking for ways to reduce the costs of disposing of the cheese byproduct whey. A company meeting was held to consider what to do with the thousands of liters of whey being produced per month. As a food...

The Complement Fixation Test and Neutralization Tests

Bacteria, red blood cells, or other cells may sometimes lyse as the result of complement activity. Recall that complement is a complex system of proteins they interact with antibody bound to antigenic components of cells (a process known as complement fixation) and cause the cells to lyse. This phenomenon is the basis for the complement fixation test, which is used to test for specific antibodies in a patient's serum. The test involves several steps (figure 17.12). For example, to test for...

Blood and Lymphatic Infections

SEM of the tip of the mouthparts of a female mosquito SEM of the tip of the mouthparts of a female mosquito lexandre Emile John Yersin (1863-1943) is one of the most interesting though relatively unknown contributors to the conquest of infectious diseases. He was born in 1863 in the Swiss village of Lavaux, where his family lived in a gunpowder factory. His father, director of the factory and a self-taught insect expert, died unexpectedly 3 weeks before Yersin's birth. Alexandre developed an...

Microcheck 152

Physical barriers that prevent entry of microorganisms into the body include the skin and mucous membranes. Various antimicrobial substances, including lysozyme, peroxidase enzymes, lactoferrin, and defensins are found on the body surfaces. The normal flora plays a protective role by excluding certain other microbes. What is the role of lactoferrin How would damage to the ciliated cells of the respiratory tract predispose a person to infection

Causative Agent Of Plaque

Poliomyelitis is caused by three types of polioviruses, designated 1, 2, and 3, which are distinguished by using antisera. These small, non-enveloped, single-stranded, positive sense RNA viruses are members of the enterovirus subgroup of the picor-navirus family. They can be grown in vitro in cell cultures, where they cause cell destruction. With low concentrations of virus, the areas of cell destruction, termed plaques, are separated from one another and are readily seen with the unaided eye...

Microbial Ecology

For centuries, farmers have understood that they could not continue growing the same crop on the same piece of land year after year without reducing the crop's yield. They knew that allowing afield to lie unplantedfor one or more seasons enables it to recover its productivity. The wild plants that grow on the field for a year or two appear to rejuvenate the soil. It was not until the late nineteenth century that scientists began to discover why this was so. They isolated soil microorganisms...

Virus Induced Tumors General Aspects

The word tumor, or neoplasm, indicates a swelling that results from the abnormal growth of cells. If the growth remains within a defined region and is not carried to other areas by the circulatory system, it is a benign tumor. If the abnormal growth spreads or metastasizes to other parts of the body, it is a malignant tumor or cancer. It is estimated that less than one in 10,000 tumor cells that escape the primary tumor survives to colonize another tissue. Because this discussion is concerned...

Streptobacillary Rat Bite Fever

Rat bites are fairly common among the poor people of large cities and among workers who handle laboratory rats. In the past, as many as one out of 10 bites resulted in rat bite fever. Currently, the disease is not reportable in any state and the incidence of the disease in the United States is unknown. Usually, the bite wound heals promptly without any problem noted. Two to 10 days later, however, chills and fever, head and muscle aches, and vomiting develop. The fever characteristically comes...

Mary

Organisms can be grouped as neutrophiles, acidophiles or alkalophiles based on their optimum pH. 1. All microorganisms require water for growth. 2. If the solute concentration is higher in the medium than in the cell, water diffuses out of the cell, causing plasmolysis. (Figure 4.5) 3. Halophiles have adapted to live in high salt environments. 4.4 Nutritional Factors that Influence Microbial Growth 1. The major elements make up cell constituents and include carbon, nitrogen, sulfur, and...

Anaerobic

Cultivation of obligate anaerobes presents a great challenge to the microbiologist, because the cells may be killed if they are exposed to O2 for even a short time. Obviously, special techniques excluding O2 are required for their cultivation. As techniques for cultivating anaerobes have improved in recent years, many more of these organisms are being isolated from various habitats, including wound and blood infections in which they had previously appeared to be absent. Anaerobes that can...

Immunoglobulin M IgM

IgM accounts for 5 to 13 of the circulating antibodies and is the first class produced during the primary response to an anti gen. It is the only class produced in response to T-independent antigens, a group of antigens that will be discussed later. IgM found circulating in the blood is a pentamer. Its large size prevents it from crossing from the bloodstream into tissues, so its role is primarily to control bloodstream infections. The five monomeric subunits give IgM a total of 10...

Microcheck 258

Trichomoniasis is a protozoan STD that involves the genital tract other protozoan STDs infect the intestine. Women itching, burning, swelling, vaginal redness, frothy, sometimes smelly, yellow-green discharge, and burning on urination. Men discharge from penis, burning on urination, painful testes, tender prostate. Many women, most men asymptomatic Trichomonas vaginalis, a protozoan with four anterior flagella, and a posterior flagellum attached to an undulating membrane a rigid rodlike...

H2n

Figure 2.17 Protein Structures (a)The primary structure is determined by the amino acid composition. (b)The secondary structure results from folding of the various parts of the protein into two major patterns helices and sheets. (c)The tertiary structure is the overall shape of the molecule, globular or fibrous. (d) Quaternary structure results from several polypeptide chains interacting to form the protein.This protein is hemoglobin and consists of two pairs of identical chains, a and b....

Cat Scratch Disease

In the United States, cat scratch disease is the most common cause of chronic lymph node enlargement at one body site in young children (figure 27.15). Despite its name, this disease can be transmitted by bites, and probably other means. Typically the infection is mild and localized, lasting from several weeks to a few months. Of the estimated 24,000 annual cases, about 2,000 require hospitalization. In about half the cases, the disease begins within a week of a scratch or bite with the...

Viruses of Bacteria

M uring the late nineteenth century, many bacteria, M M fungi, and protozoa were identified as infectious A organisms. Most of these organisms could be readily seen with a microscope, and they generally could be grown in the laboratory. In the 1890s, D. M. Iwanowsky and Martinus Beijerinck found that a disease of tobacco plants, called mosaic disease, was caused by an agent different from anything that was known. About 10 years later, F. W. Twort in England and F. d'Herelle in France showed...

Virus HIV Infection and AIDS

Microorganisms such as Pneumocystis carinii are common, but of such low virulence that they only cause disease in individuals with immunodeficiency disorders. When such a disease appears, it strongly suggests that the victim is immunodeficient. In the United States in 1981, a number of cases of P. carinii pneumonia in previously healthy homosexual men first led to the recognition of AIDS. The acronym AIDS, for acquired immunodeficiency syndrome, was first used in 1982 by the Centers for Disease...

The Green Bacteria

The green bacteria are Gram-negative organisms that are typically green or brownish in color. Unlike the purple bacteria, their accessory pigments are located in structures called chloro-somes and their cytoplasmic membranes do not have extensive invaginations. accessory pigments, p. 156 The green sulfur bacteria are found in habitats similar to those preferred by the purple sulfur bacteria. Like the purple sulfur bacteria, they use hydrogen sulfide as a source of electrons for reducing power...

The Cyanobacteria

Nitrogen Fixation Enzyme

The cyanobacteria are a diverse group of more than 60 genera of Gram-negative bacteria. They inhabit a wide range of environments, including freshwater and marine habitats, soils, and the surfaces of rocks. In addition to being photosynthetic, many are able to convert nitrogen gas (N2) to ammonia, which can then be incorporated into cell material. This process, called nitrogen fixation, is an exclusive ability of prokaryotes. nitrogen fixation, p. 775 General Characteristics of Cyanobacteria...

Group Translocation

Group translocation is a transport process that chemically alters a molecule during its passage through the cytoplasmic membrane (figure 3.30). Consequently, uptake of that molecule does not alter the concentration gradient. As an example, glucose and several other sugars are phosphorylated during their transport into the cell by the phosphotransferase system. The energy expended to phosphorylate the sugar can be regained when that sugar is later broken down to provide energy. Figure 3.28...

Of Immunodeficiency

n 1981, five published reports described an illness in previously healthy young homosexual men, characterized by unusual JL opportunistic infections, certain malignant tumors, and immunodeficiency. The constellation of symptoms and signs associated with this illness came to be known as AIDS, an acronym for acquired immunodeficiency syndrome. Initially, there was wild speculation about what might be the cause of AIDS, but by 1982, the Centers for Disease Control had convincing epidemiological...

Structure and Arrangement of Flagella

Polar Flagella

Flagella are composed of three basic parts (figure 3.39). The filament is the portion extending into the exterior environment. It is composed of identical subunits of a protein called fla-gellin. These subunits form a chain that twists into a helical structure with a hollow core. Connecting the filament to the cell surface is a curved structure, the hook. The basal body anchors the flagellum to the cell wall and cytoplasmic membrane. The numbers and arrangement of flagella can be used to...

The Structure Of The Prokaryotic Cell

The overall structure of the prokaryotic cell is deceptively simple (figure 3.23). The cytoplasmic membrane surrounds the cell, acting as a barrier between the external environment and the interior of the cell. This membrane permits the passage of only certain molecules into and out of the cell. Enclosing the cytoplasmic membrane is the cell wall, a rigid barrier that functions as a tight corset to keep the cell contents from bursting out. Cloaking the wall may be additional layers, some of...

Proteins and Their Functions

Proteins constitute more than 50 of the dry weight of cells. Of all the macromolecules, they are the most versatile in what they do in cells. A typical bacterial cell contains 600 to 800 different kinds of proteins at any one time. In the microbial world, proteins are responsible for Catalyzing all reactions of the cell required for life. The structure and shape of certain structures such as ribosomes, the protein-building machinery in all cells. Cell movement by flagella. flagella, p. 63...

Viral Infections of the Upper Respiratory System

The average person in the United States suffers two to five episodes of viral upper respiratory infections each year. They generally subside without any treatment and rarely cause permanent damage. Most of the causative agents are highly successful parasites, using us to replicate themselves to astronomical numbers, then moving on without killing us or even leaving long-standing immunity. Although hundreds of kinds of viruses are involved, the range of symptoms they produce is similar. Their...

Atoms and Elements

Atoms, the basic units of all matter, are made up of three major components the negatively charged electrons positively charged protons and uncharged neutrons (figure 2.1). The protons and neutrons, the heaviest components, are found in the heaviest part of the atom, the nucleus. The very light electrons orbit the nucleus. The number of protons normally equals the number of electrons, and so the atom as a whole is uncharged. The relative sizes and motion of the parts of an atom can be...

Directed Movement of Molecules Across the Cytoplasmic Membrane

Nearly all molecules that enter or exit a cell must cross the otherwise impermeable cytoplasmic membrane through proteins that function as selective gates. Mechanisms allowing nutrients and other small molecules to enter the cell are called transport 3.5 Directed Movement of Molecules Across the Cytoplasmic Membrane 55 systems. Some of these same mechanisms are used to expel wastes and compounds that are otherwise deleterious to the cell. This function of transport systems is sometimes called...

Causative Agents

The causative agents are the Sin Nombre, Spanish for no name, virus and various related hantaviruses that exist at different locations in the Western Hemisphere. The hantaviruses are enveloped viruses of the bunyavirus family. Their genome consists of three Table 23.12 Respiratory Syncytial Virus (RSV) Infections Table 23.12 Respiratory Syncytial Virus (RSV) Infections Runny nose, cough, fever, wheezing, difficulty breathing, dusky color RSV, a paramyxovirus that produces syncytia Sloughing of...

The Purple Bacteria

The purple bacteria are Gram-negative organisms that appear red, orange, or purple due to their light-harvesting pigments. Unlike other anoxygenic phototrophs, the components of their photosynthetic apparatus are all contained within the cytoplas-mic membrane. Invaginations in this membrane effectively increase the surface area available for the photosynthetic processes. Purple sulfur bacteria can sometimes be seen growing as colored masses in sulfur-rich habitats such as sulfur springs (figure...

Phase of Prolonged Decline

The phase of prolonged decline is marked by a very gradual decrease in the number of viable cells in the population, lasting for months to years. Superficially, it might seem like a gradual march towards death of the population, but dynamic changes are actually occurring. Many members of the population are dying and releasing their nutrients, while a few fitter cells that are more able to cope with the deteriorating environmental conditions are actively multiplying. This dynamic process...

Morphology of Prokaryotic Cells

Prokaryotes come in a variety of simple shapes and often group together, forming chains or clusters. These characteristics, particularly the shape, are used to describe, classify, and identify microorganisms. Most common bacteria are one of two shapes spherical, called a coccus (plural cocci) and cylindrical, called a rod (figure 3.20). A rod-shaped bacterium is sometimes called a bacillus (plural bacilli). The descriptive term bacillus should not be confused with Bacillus, the name of a genus....

Review Q

Name two substances released by lactobacilli that help protect the vagina from potential pathogens. 2. List four things that predispose to the development of infection of the urinary bladder. 4. Name two genera of bacteria that infect the kidneys from the bloodstream. 5. What possible danger lurks in a spot on the ground where an animal has urinated 1 week earlier 6. What probably causes the Jarisch-Herxheimer reaction 7. What causes the characteristic odor of bacterial vaginosis 9. How does...

Group A Streptococcal Flesh Eaters

Strep Fasciitis

Streptococcus pyogenes was introduced in the chapters on skin and respiratory infections as the cause of strep throat, scarlet fever, and other conditions. It is also a common cause of wound infections, which have generally been easy to treat since the bacteria are consistently susceptible to penicillin. Occasionally, however, S. pyogenes infections can progress rapidly, even leading to death despite antimicrobial treatment. These more severe infections are called invasive and include...

What Is The Causitive Agent Of Bread Mold

Black Spores Mycelium Cakes

310 Chapter 12 The Eukaryotic Members of the Microbial World 310 Chapter 12 The Eukaryotic Members of the Microbial World Figure 12.16 Examples of a Mycelium on Various Foods (a)The cottony white mass inside the potato is an example of a mycelium. (b) Magnified hyphae of Rhizopus stolonifer, black bread mold, showing the hyphae and the spores. Figure 12.16 Examples of a Mycelium on Various Foods (a)The cottony white mass inside the potato is an example of a mycelium. (b) Magnified hyphae of...

Surface Layers External to the Cell Wall

Bacteria may have one or more layers outside of the cell wall. The functions of some of these are well established, but that of others are unknown. Many bacteria envelop themselves with a gel-like layer called a glycocalyx that generally functions as a mechanism of either protection or attachment (figure 3.37). If the layer is distinct and gelatinous, it is called a capsule. If, instead, the layer is diffuse and irregular, it is called a slime layer. Colonies of bacteria that form either of...

Role Of Co2 As The Main Causative Agent

Consumed is employed to create biomass, however some is used as an energy source, generating carbon dioxide as a product. As plants lose their leaves, and members of the food web die, various decomposers degrade the resulting detritus, using it both as an energy source and to create biomass. The type of organic material helps dictate which species are involved in the degradation. For example, a wide variety of organisms utilize the more readily decomposable organic substances such as sugars,...

Csd

Figure 25.3 Leptospira interrogans, the Cause of Leptospirosis Note the hooked ends of this spirochete. Figure 25.3 Leptospira interrogans, the Cause of Leptospirosis Note the hooked ends of this spirochete. the site of entry, but the organisms multiply and spread throughout the body by way of the bloodstream, penetrating all tissues including the eyes and the brain. Severe pain is characteristic of this first (septicemic) phase, and it may lead to unnecessary surgery for suspected appendicitis...

Epidemiology

About 30 of women develop cystitis at some time during their life. Factors involved in urinary infections in women include A relatively short urethra. The position of the urethra makes it subject to fecal contamination and colonization with potentially pathogenic intestinal bacteria that have only a few centimeters to traverse to the bladder. Sexual intercourse. About one-third of urinary tract infections in sexually active women are associated with sexual intercourse. Bladder infections in...

Pathogenesis

Generally, the causative agents reach the bladder by ascending from the urethra. The process is aided by motility of the organisms. Urine is a good growth medium for many species of bacteria. Species of E. coli that infect the urinary system possess pili that attach specifically to receptors on the cells that line the bladder. Experimental evidence indicates that attachment is followed by death and sloughing of the superficial layer of epithelium, followed by penetration of newly exposed cells...

Microcheck 252

Normally the urine and urinary tract are free of microorganisms above the entrance to the bladder, but the lower urethra hosts a number of genera of bacteria. During the child-bearing years, a woman's hormones are important in the vagina's resistance to infection, because estrogen promotes growth of lactobacilli and acidic conditions. Which parts of the genitourinary system are normally sterile Name two species of pathogenic bacteria to which the vagina is especially susceptible during...

Applications of Genetic Engineering

Genetic engineering brought biotechnology into a new era by providing a powerful tool for manipulating E. coli and other microorganisms for medical, industrial, or research uses (table 9.2). More recently, techniques that permit the genetic engineering of plants and animals have been developed. Genetic engineering relies on DNA cloning, a process that involves isolating the DNA from one organism, using restriction enzymes to cut the DNA into fragments called restriction fragments, and then...

Apc

Blistery Rash From Test

(d) Antigen-presenting cells present the hapten-peptide complex to sensitized Th1 cells, which secrete cytokines and attract macrophages the macrophages are activated and secrete mediators of inflammation that cause skin lesions. Figure 18.7 Poison Oak Dermatitis Is an Example of Type IV Hypersensitivity Delayed Cell-Mediated (e) Characteristic skin lesions appear after 24 hours, reaching their peak at 48-72 hours after exposure to the plant. cytokines when they come into contact again with the...

Food Spoilage

Food spoilage encompasses any undesirable changes in food. Spoilage microorganisms and their microbial metabolites that cause repugnant tastes and odors, although aesthetically disagreeable, generally are not harmful. This is not surprising when their growth requirements are considered. Most human pathogens grow best at temperatures near 37 C, whereas most foods are usually stored at temperatures well below the normal body temperature. Similarly, the nutrients available in fruits, vegetables,...

Plate Counts

Plate counts measure the number of viable cells in a sample by exploiting the fact that an isolated cell on a nutrient agar plate will give rise to one colony. A simple count of the colonies determines how many cells were in the initial sample (figure 4.13). The two different plating methods, pour-plate and spread-plate, differ in how the suspension of bacteria is applied to the agar plate. As the ideal number of colonies to count is between 30 and 300, and samples frequently contain many more...

X174

*ds, double-stranded ss, single-stranded. *ds, double-stranded ss, single-stranded. Lytic Phage Replication by Double-Stranded DNA Phages In all lytic phage infections, the phage nucleic acid enters the bacterium while its protein coat remains on the outside. Since only nucleic acid enters the cell, the nucleic acid must code for the protein in the phage coat. The nucleic acid is replicated along with phage proteins, resulting in the formation of many virions. At the end of the replication...

Temperature and Disease

Wide variations exist in the temperature of various parts of the human body. Although the heart, brain, and gastrointestinal tract are near 37 C, the temperature of the extremities may be much lower. For these reasons, some microorganisms can cause disease in certain body parts but not in others. For example, Hansen's disease (leprosy) typically involves the coolest regions of the body (ears, hands, feet, and fingers) because the causative organism, Mycobacterium leprae, grows best at these...

Principles of Bacterial Growth

Bacteria generally multiply by the process of binary fission. After a bacterial cell has increased in size and doubled all of its parts, it divides (figure 4.3). One cell divides into two, those two divide to become four, those four become eight, and so on. In other words, the increase in cell numbers is exponential. Because it is Nester-Anderson-Roberts I I. Life and Death of I 4. Dynamics of Prokaryotic I I The McGraw-Hill 4.2 Principles of Bacterial Growth 85 (8) Isolated colonies develop...

Antigenic Shift

Figure 23.22 Influenza Virus Antigenic Drift and Antigenic Shift With drift, repeated mutations cause a gradual change in the antigens composing the hemagglutinin, so that antibody against the original virus becomes progressively less effective. With shift, there is an abrupt, major change in the hemagglutinin antigens because the virus acquires a new genome segment, which in this case codes for hemagglutinin. Changes in neuraminidase could occur by the same mechanism. Nester-Anderson-Roberts I...

N

Why is it important for a cell that allosteric inhibition be reversible The three central metabolic pathways glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle modify organic molecules in a step-wise fashion to form Intermediates with high-energy bonds that can be used to synthesize ATP by substrate-level phosphorylation Intermediates that can be oxidized to generate reducing power Intermediates and end products that function as...

Alcohols

Aqueous solutions of 60 to 80 ethyl or isopropyl alcohol rapidly kill vegetative bacteria and fungi. They do not, however, reliably destroy bacterial endospores and some naked viruses. Alcohol probably acts by coagulating enzymes and other essential proteins and by damaging lipid membranes. Proteins are more soluble and denature more easily in alcohol mixed with water, which is why aqueous solutions are more effective than pure alcohol. Solutions of alcohol are commonly used as antiseptics to...

Archaea that Thrive in Extreme Conditions

Members of the Archaea that have been characterized typically thrive in extreme environments that are otherwise devoid of life. These include conditions of high heat, acidity, alkalinity, and salinity. An exception to this attribute is the methanogens, which inhabit anaerobic niches shared with members of the Bacteria. Because of their intimate association with bacteria, the methanogens were discussed earlier in the chapter. The Archaea fall into two broad phylogenetic groups the Euryarchaeota...

Mucous Membranes

The cells of the mucous membranes, or mucosa, are constantly bathed with mucus and other secretions that help wash microbes from the surfaces. Some mucous membranes have mechanisms that propel microorganisms and viruses, directing them toward areas where they can be eliminated more easily. For example, peristalsis, the rhythmic contractions of the intestinal tract that propels food and liquid, also helps expel microbes. The respiratory tract is lined with ciliated cells the hairlike cilia...

Jex

Phagolysosome

(a) Chemoattractants, such as C5a, attract phagocyte to organisms to be ingested (b) C3b coats organisms and attaches to C3b receptors on phagocyte (b) C3b coats organisms and attaches to C3b receptors on phagocyte (g) Contents of phagolysosome eliminated by exocytosis (c) Organism is engulfed into a phagosome fuses with lysosome to produce phagolysosome (e) Organism is killed within the phagolysosome (f) Digestion and breakdown of organism within phagolysosome (c) Organism is engulfed into a...

Selective Media

Selective media inhibit the growth of organisms other than the one being sought. For example, Thayer-Martin agar is used to isolate Neisseria gonorrhoeae from clinical specimens. This is chocolate agar to which three or more antimicrobial drugs have been added. The antimicrobials inhibit fungi, Gram-positive bacteria, and Gram-negative rods. Because these drugs do not inhibit most strains of N. gonorrhoeae, they allow growth with little competition from other organisms. Table 4.6 Ingredients in...

Review Questions

Describe why a microbial mat has green, pink, and black layers. 2. Why do lakes in temperate regions stratify during the summer months 3. Why is there a high concentration of microbes in the rhizosphere 4. What dictates whether a form of an element is suitable for use as an energy source versus a terminal electron acceptor 5. Why does wood resting at the bottom of a bog resist decay 6. What is the importance of nitrogen fixation 7. Describe the relationship between ammonia oxidizers and nitrite...

Nosocomial Infections

A hospital can be seen as a high-density population made up of unusually susceptible people where the most antimicrobial-resistant and virulent pathogens can potentially circulate. Considering this, it is not surprising that hospital-acquired infections, or nosocomial infections, have been a problem since hospitals began (nosocomial is derived from the Greek word for hospital). Modern medical practices, however, including the extensive use of antimicrobial drugs and invasive therapeutic...

Causative Agent For Instrument Error Measurement

Microscopic observation all cells in large square counted. Sample added here. Whole grid has 24 large squares, a total area of 1 sq mm and a total volume of 0.02 mm3. 4.6 Methods to Detect and Measure Bacterial Growth 97 Table 4.7 Methods Used to Measure Bacterial Growth Direct microscopic count Cell-counting instruments Membrane filtration Most probable number Total weight Chemical constituents Measuring Cell Products Used to determine total number of cells can be used for those bacteria that...

Viral Diseases of the Lower Alimentary System

Viral infections of the lower alimentary system represent a major illness burden on all age groups. Both the intestine and accessory organs such as the liver can be affected. At least five different groups of viruses can cause epidemic gastroenteritis, resulting in millions of cases each year in the United States. More than six different viruses can cause hepatitis, meaning inflammation of the liver. Hepatitis A virus (HAV), hepatitis B virus (HBV), and hepatitis C virus (HCV) account for most...

Mechanisms of Eukaryotic Pathogenesis

Pathogenesis of eukaryotic cells including fungi and protozoa include the same basic scheme as that of bacterial pathogens colonization, evasion of host defenses, and damage to the host. The mechanisms, however, are generally not well understood. Most fungi, such as yeasts and molds, are saprophytes, meaning that they acquire nutrients from dead and dying material those that can cause disease are generally opportunists, although notable exceptions exist. A group of fungi referred to as...

Causative Agent Of Cytomegalovirus

Cytomegalovirus (CMV) is a member of the herpesvirus family, which includes herpes simplex virus, Epstein-Barr virus, and varicella-zoster virus, any of which can cause troublesome symptoms in patients with immunodeficiency. CMV, like other her-pesviruses, is commonly acquired early in life and then remains latent. With impairment of the immune system, the infection activates and can cause severe symptoms. Symptoms of cytomegalovirus disease follow a pattern similar to that of toxoplasmosis....

Aids

Map Ofworld And Laitude

AIDS, acquired immunodeficiency syndrome, unquestionably the most important sexually transmitted disease of the twentieth century, is covered briefly here and more fully in chapter 29. The AIDS epidemic was first recognized in the United States in 1981. Figure 25.20 The AIDS Pandemic Continues Without Letup During 1998 alone an estimated 5.8 million people became newly infected with the human immunodeficiency virus, and most of them will ultimately die of AIDS. Figure 25.20 The AIDS Pandemic...

Gccggaaugcugcuggc

Aspartic acid threonine leucine glycine 6. Allolactose induces the lac regulon by binding to a(n) A. operator. B. repressor. 7. Under which of the following conditions will transcription of the lac operon occur A. Lactose present glucose present B. Lactose present glucose absent C. Lactose absent glucose present D. Lactose absent glucose absent 8. Which of the following statements about gene expression is false A. More than one RNA polymerase can be transcribing a specific gene at a given time....

The Ecology of Lyme Disease

Yme disease is often referred to as one of the emerging diseases. Unrecognized in the United States before 1975, it is ' now the most commonly reported vector-borne disease. Because of the seeming explosion in the numbers of Lyme disease cases, and its apparent extension to new geographical areas, the ecology of Lyme disease is under intense study. In the northeastern United States, large increases in white-footed mouse populations occur in oak forests during years in which there is a heavy...

Bacterial Infections of the Upper Respiratory System

A number of different species of bacteria can infect the upper respiratory system. Some, such as Haemophilus influenzae and -hemolytic streptococci of Lancefield group C, can cause sore throats but generally do not require treatment because the bacteria are quickly eliminated by the immune system. Other infections require treatment because they are not so easily eliminated and can cause serious complications. Strep Throat (Streptococcal Pharyngitis) Sore throat is one of the most common reasons...

HIV Disease

Hairy Leukoplakia

Almost everyone who becomes infected with HIV develops HIV disease, marked by slow destruction of their immune system, eventually ending in AIDS. The first symptoms of HIV disease appear after an incubation period of 6 days to 6 weeks and usually consist of fever, headache, sore throat, muscle aches, enlarged lymph nodes, and a generalized rash. Some subjects develop central nervous system symptoms ranging from moodiness and confusion to seizures and paralysis. These symptoms constitute the...

O N S

Name three food products produced with the aid of microorganisms. 8. In photosynthesis, what is encompassed by the term light-independent reactions 9. Unlike the oxygenic phototrophs, the anoxygenic phototrophs do not evolve oxygen (O2). Why not 10. What is the role of transamination in amino acid biosynthesis 166 Chapter 6 Metabolism Fueling Cell Growth Multiple Choice 1. Which of these environmental factors does not affect general enzyme activity A. Temperature B. Inhibitors C. Coenzymes D....

Chanchroid Causative Agent

Most of the bacteria that cause STDs survive poorly in the environment and require intimate contact for transmission. 1. Gonorrhea is caused by Neisseria gonorrhoeae, has been generally declining in incidence, but it is still one of the most commonly reported bacterial diseases. (Figures 25.8,25.9) 2. Men usually develop painful urination and thick pus draining from the urethra women may have similar symptoms, but they tend to be milder and are often overlooked. 3. Expression of different...

Chipmunks In Medical Research

During epidemic viral encephalitis, only a minority of those infected develop encephalitis. Others develop viral meningitis, fever and headache only, or no symptoms at all. These diseases are all zoonoses maintained in nature in birds or rodents, humans being an accidental host. In the United States, LaCrosse encephalitis virus usually causes most of the reported encephalitis cases. In its natural cycle (figure 26.13), the LaCrosse virus infects Aedes mosquitoes, which pass it directly from one...

Viral Diseases of the Nervous System

Many different kinds of viruses can infect the central nervous system, including the Epstein-Barr virus of infectious mononucleosis the mumps, rubeola, varicella-zoster, and herpes simplex viruses and more commonly, human enteroviruses and the viruses of certain zoonoses. In most cases, nervous system involvement occurs in only a very small percentage of people infected with the viruses. The next section discusses four kinds of illness resulting from viral central nervous system infections...

Branched Cells That Gather Antigen From Tissues Bring To Lymphctyes

Lobed nucleus granules in cytoplasm ameboid appearance Large eosinophilic granules non-segmented or bilobed nucleus Lobed nucleus large basophilic granules Single nucleus little cytoplasm before differentiation Account for most of the circulating leukocytes few in tissues except during inflammation and in reserve locations Few in tissues except in certain types of inflammation and allergies Basophils in circulation mast cells present in most tissues In circulation they differentiate into either...

Regulating Gene Expression

To cope with changing conditions in their environment, microorganisms have evolved elaborate control mechanisms to synthesize the maximum amount of cell material from a limited supply of energy. This is critical, because generally a microorganism must reproduce more rapidly than its competitors in order to be successful. Consider the situation of Escherichia coli. For over 100 million years, it has successfully inhabited the gut of mammals, where it reaches concentrations of 106 cells per...

Case Presentation

The patient was a 35-year-old man who consulted his physician because of upper abdominal pain.The pain was described as a steady burning or gnawing sensation, like a severe hunger pain. Usually it came on 1 1 2 to 3 hours after eating, and sometimes it woke him from sleep. Generally, it was relieved in a few minutes by food or antacid medicines. On examination, the patient appeared well, without evidence of weight loss.The only positive finding was tenderness slightly to the right of the...

R Plasmid

Figure 8.22 Two Regions of an R Plasmid The R (resistance) genes code for resistance to various antimicrobials the RTF (resistance transfer factor) region codes for plasmid replication and the transfer of the plasmid to other bacteria. Figure 8.22 Two Regions of an R Plasmid The R (resistance) genes code for resistance to various antimicrobials the RTF (resistance transfer factor) region codes for plasmid replication and the transfer of the plasmid to other bacteria.

Terrestrial Habitats

Although microbes may adhere to and grow on a variety of objects on land, the focus in this section will deal with soil, as it is a critical component of terrestrial ecosystems. Extreme terrestrial habitats, such as volcanic vents and fissures, and the extremophiles that inhabit them are described in chapter 11. extreme thermophiles, p. 293 thermophilic extreme acidophiles, p. 294 Human interest in the microbiology of soil stems partly from the ability of microbes to synthesize a variety of...

Biotechnology and Recombinant DNA

n September of 1976, Argentinean newspapers reported a violent shootout that had occurred between soldiers and the JL. occupants of a house in suburban Buenos Aires, leaving the five extremists inside dead. Conspicuously absent from those reports was the identity of the extremists a young couple and their three children, ages six years, five years, and six months. Over the next seven years, similar scenarios recurred as the military junta that ruled Argentina eliminated thousands of its...

The Plasma Membrane

All eukaryotic cells have a cytoplasmic membrane, or plasma membrane, which is similar in chemical structure and fUnction to that of prokaryotic cells. It is a typical phospholipid bilayer embedded with proteins. The lipid and protein composition of the leaflet that faces the cytoplasm, however, differs significantly from that facing the outside of the cell. The same is true for membranes that surround the organelles. The leaflet facing the lumen of the organelle is similar to its counterpart...