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...

Info

Van Leeuwenhoek's engravings (1.5x), 1695 Microbiology as a science was born in 1674 when Antony van Leeuwenhoek (1632-1723), an inquisitive Dutch drapery merchant, peered at a drop of lake water through a glass lens that he had carefully ground. It was known for several centuries previous that curved glass would magnify objects, but it took the skillful hands of a craftsman coupled with the questioning mind of an amateur scientist to revolutionize the understanding of the world in which we...

IgA

The monomeric form of IgA accounts for about 10 to 13 of antibodies in the blood of healthy individuals. Most IgA antibodies, however, are the secreted form, called secretory IgA (sIgA). In fact, IgA is the most abundant immunoglobulin class produced, even though it makes up only a small fraction of the antibodies in blood. The secreted form is important in mucosal immunity and is found on the mucous membranes that line the gastrointestinal, genitourinary, and respiratory tracts and in...

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

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....

Microcheck 133

Bacterial genes from a donor can be transferred to recipient bacteria following the incorporation of bacterial genes in place of phage genes in the virion. After the phage lyse the donor bacteria and infect the recipient cells, the bacterial genes are integrated into the chromosome of the recipient cell, the process of transduction. There are two types of transduction generalized, in which any gene of the host can be transferred and specialized, in which only the gene near the site at which the...

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...

Pathogenesis

The normal skin is generally resistant to invasion by dermatophytes. Some species, however are relatively virulent and can even cause epidemic disease, especially in children. In conditions of excessive moisture, dermatophytes can invade keratinized structures, including the epidermis down to the level of the keratin-producing cells. A keratinase enables them to dissolve keratin and use it as a nutrient. Hair is invaded at the level of the hair follicle because the follicle is relatively moist....

Symptoms

Most people colonized by these molds have no symptoms at all. Others complain of itching, a bad odor, or a rash. In ringworm, a rash occurs at the site of the infection and consists of a scaly area surrounded by redness at the outer margin, producing irregular rings or a lacy pattern on the skin. On the scalp, patchy areas of hair loss can occur, with a fine stubble of short hair left behind. Involved nails become thickened and brittle and may separate from the nailbed. Sometimes, a rash...

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

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...

Causative Agent

Dental caries is caused principally by Streptococcus mutans and closely related species. The bacteria live only on the teeth and cannot colonize the mouth in the absence of teeth. They produce lactic acid as a by-product of their metabolism of sugars, and unlike many other bacteria, they thrive under acidic conditions below pH 5. Another important feature is that they produce insoluble extracellular glucans from sucrose, but not from other sugars. Glucans, polysaccharides composed of repeating...

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...

Microcheck

Direct microscopic counts and cell-counting instruments generally do not distinguish between living and dead cells. Plate counts determine the number of cells capable of multiplying membrane filtration can be used to concentrate the sample. The most probable number is a statistical assay based on the theory of probability. Turbidity of a culture is a rapid measurement that can be correlated to cell number. The total weight of a culture and the amount of certain cell constituents can be...

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.

Anatomy and Physiology

The alimentary tract, sometimes referred to as the gastrointestinal or GI tract, is the passageway running from the mouth to the anus. Like the skin, it is one of the body's boundaries with the environment, and it is one of the major routes into the body for invading microbial pathogens. The alimentary tract and its accessory organs, the saliva-producing glands, liver, and pancreas, together compose the alimentary system, the main purpose of which is to provide nourishment for the body. The...

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...

O

Introduce recombinant molecule into new host Figure 9.2 The Steps of a Cloning Experiment Figure 9.3 Cloning into a High-Copy-Number Plasmid When a gene is inserted into a high-copy-number plasmid, multiple copies of that gene will be present in a single cell, resulting in the synthesis of many more molecules of the encoded protein. Figure 9.3 Cloning into a High-Copy-Number Plasmid When a gene is inserted into a high-copy-number plasmid, multiple copies of that gene will be present in a single...

Type IV Hypersensitivities Delayed Cell Mediated

Harmful effects produced by the mechanisms of cell-mediated immunity are referred to as delayed hypersensitivity. The name reflects the slowly developing response to antigen reactions peak at 2 to 3 days rather than in minutes as in immediate hypersensitivity. As would be expected with cell-mediated responses, T cells are responsible and antibodies are not involved. Delayed hypersensitivity reactions can occur almost anywhere in the body. They are wholly or partly responsible for contact...

The Anatomical Barriers As Ecosystems

The skin and mucous membranes provide anatomical barriers against invading microorganisms, but they also supply the foundation for a complex ecosystem, an interacting biological community. The microbial community that resides on humans is important from a medical standpoint because it offers protection from some disease-causing organisms. At the same time, members of the normal flora are a common cause of infection in people who are immunocompromised. The intimate interactions between the...

Protozoan Diseases

Protozoa infect the blood vascular and lymphatic systems of millions of people worldwide. One example, discussed in an earlier chapter, is Trypanosoma brucei, fundamentally a bloodstream parasite of African animals and cause of African sleeping sickness in humans. Another trypanosome, T. cruzi, causes chagas disease (American trypanosomiasis), often manifest as a chronic heart infection. Protozoans of the genus Leishmania cause visceral leishmaniasis, with enormous splenic enlargement, and a...

Crocheck 193

A primary pathogen can cause disease in an otherwise healthy individual an opportunist causes disease in an immunocompromised host. The course of infectious disease includes an incubation period, illness, and a period of convalescence. Infections may be acute or chronic, latent, localized, or systemic. Why are opportunists causing disease more frequently Give an example of a latent disease. What factors might contribute to a long incubation period

Viruses Prions and Viroids Infectious Agents of Animals and Plants

Transmission electron micrograph (TEM) of rotavirus (x575,000) Ithough scientific reports as early as the eighteenth century suggested that invisible agents might cause * * tumors, not until the early twentieth century did this idea gain strong experimental support. At that time, Dr. Peyton Rous of the Rockefeller Institute caused tumors in healthy chickens by injecting them with a filtered suspension of ground-up cells from tumors of other chickens. These studies were not taken very seriously,...

Mary

An abscess is composed of a collection of pus, which is composed of leukocytes, components of tissue breakdown, and infecting organisms. 2. Abscess formation localizes an infection within tissue to prevent its spread inflammatory cells and clotted blood vessels separate the abscesses from normal tissue. (Figure 27.2) 712 Chapter 27 Wound Infections Anaerobic Wounds 1. Anaerobic conditions are likely to occur in wounds containing dead tissue or foreign material, and those with a narrow opening...

That Complicate Acquired Immunodeficiencies

Certain malignant tumors are associated with HIV disease, organ transplantation, and other acquired immunodeficiency states. Most of these malignancies fall into one of only three types Kaposi's sarcoma, lymphomas, and carcinomas arising from anal or cervical epithelium. They tend to metastasize, meaning jump to new areas, and be difficult to treat. Evidence indicates that viruses are a factor in their causation. A popular theory is that certain viral antigens, perhaps with the aid of...

The Role of Dendritic Cells in TCell Activation

Naive T cells slowly circulate among the secondary lymphoid organs as a means of encountering antigens. Immature dendritic cells, meanwhile, reside in peripheral tissues, such as beneath the skin, gathering various materials from those areas (figure 16.20). The dendritic cells use both phagocytosis and pinocy-tosis to take up particulate and soluble material that could potentially contain foreign protein. After collecting substances from the periphery, the dendritic cells travel to the...

U E S T I O N S

Staphylococcus aureus can be responsible for which of these following conditions A. Impetigo B. Food poisoning C. Toxic shock syndrome D. Scalded skin syndrome E. All of the above 3. The main effect of staphylococcal protein A is to A. interfere with phagocytosis. B. enhance the attachment of the Fc portion of antibody to phagocytes. 4. Which of the following is essential for the virulence of Streptococcus pyogenes A. Protease B. Hyaluronidase C. DNase D. All of the above E. None of the above...

Microcheck 253

Situations that interfere with the normal flow of urine predispose to urinary system infections. Bladder infections are common, especially in women, caused by bowel bacteria ascending from the urethra. Pyelonephritis is a feared complication. Leptospirosis is a widespread zoonosis spread by urine, in which the kidneys are infected from the bloodstream. Usually Wafer or animal urine contaminated with Leptospira sp. splashes onto mucous membrane or abraded skin (2) The bacteria infect the...

Putrefying Agents

Figure 30.4 Growth of Microbial Populations in Unpasteurized Raw Milk at Room Temperature Production of acid causes souring and encourages growth of fungi. Eventually bacteria digest the proteins, causing putrefaction. Figure 30.4 Growth of Microbial Populations in Unpasteurized Raw Milk at Room Temperature Production of acid causes souring and encourages growth of fungi. Eventually bacteria digest the proteins, causing putrefaction. and then a third. An example of such a microbial succession...

Rabies

In the United States, immunization of dogs against rabies has practically eliminated them as a source of human disease. The rabies virus remains rampant among wildlife, however, a constant threat to non-immunized domestic animals and humans. Many questions remain about the pathogenesis of rabies, and no effective treatment exists for the disease. Rabies is one of the most feared of all diseases because its terrifying symptoms almost invariably end with death. Like many other viral diseases, it...

The Nature of Antigens

The term antigen was initially coined in reference to compounds that elicited the production of antibodies it is derived from the descriptive expression antibody generator. The compounds observed to induce the antibody response are recognized as being foreign to the host by the adaptive immune system. They include an enormous variety of materials, from invading microbes and their various products to plant pollens. Today, the term antigen is used more broadly to describe any molecule that reacts...

Transmissible Spongiform Encephalopathy in Humans

Transmissible spongiform encephalopathy is rare in humans, occurring in only 0.5 to 1 case per million people. Most cases occur sporadically as Creutzfeld-Jakob disease, although there are other forms of the disease that run in families. Another form, kuru, is associated with cannibalism, as formerly practiced by some New Guinea natives. Early symptoms include vague behavioral changes, anxiety, insomnia and fatigue, which progress over weeks or months to the hallmarks of the disease, muscle...

Prevention and Treatment

Acyclovir and similar medications inhibit HSV DNA polymerase and halt the progress of herpes simplex, but they do not affect the latent virus and thus cannot rid the body of HSV infection. These medications are useful for treating severe cases and for preventing disabling recurrences. Since the ultraviolet portion of sunlight can trigger recurrent disease, sunscreens are sometimes a helpful preventive. DNA polymerase, p. 171 Some of the main features of herpes simplex are shown in table 24.3....

Hsv2

Varicella-zoster virus (herpesvirus family) Cytomegalovirus (CMV herpesvirus family) Usually subclinical except in fetus or immunocompromised host CMV pneumonia, eye infections, mononucleosis-like symptoms Salivary glands, kidney epithelium, leukocytes Epstein-Barr virus (herpesvirus family) B cells, which are involved in antibody production Chapter 14 Viruses, Prions, and Viroids Infectious Agents of Animals and Plants Chapter 14 Viruses, Prions, and Viroids Infectious Agents of Animals and...

Biogeochemical Cycling and Energy Flow

Biogeochemical cycles are the cyclical paths that elements take as they flow through living (biotic) and non-living (abiotic) components of ecosystems. These cycles are important, because a fixed and limited amount of the elements that make up living cells exists on the earth and in the atmosphere. Thus, in order for an ecosystem to sustain its characteristic life forms, elements must continuously be recycled. For example, if the organic carbon that animals use as an energy source and exhale as...

Summary

26.1 Anatomy and Physiology (Figure 26.1) 1. The brain and spinal cord make up the central nervous system (CNS) the peripheral nervous system is composed of motor nerves and sensory nerves. 2. Cerebrospinal fluid is produced by structures in cavities inside the brain and flows out over the brain and spinal cord. 3. Meninges are the membranes that cover the surface of the brain and spinal cord. Pathways to the Central Nervous System 1. Infectious agents can reach the CNS by way of the...

Using Phenotypic Characteristics to Classify Prokaryotes

Traditionally, relatedness of different prokaryotes has been decided by comparing their phenotypic characteristics. Numerical taxonomy determines relatedness based on the percentage of characteristics that two groups have in common. In this approach, the investigator conducts a large number of tests to determine whether certain features are present or absent in an organism. These tests include such characteristics as the ability to degrade lactose, the ability to form endospores, and the...

Aquatic Habitats

Oceans, covering more than 70 of the earth's surface, are the most abundant aquatic habitat, representing about 95 of the global water. They are the marine environment. Although lakes and rivers, the fresh water environments, represent only a small fraction of the total water, they are important sources of fresh water. Deep lakes and oceans have characteristic zones that influence the distribution of microbial populations. The uppermost layer, where sufficient light penetrates, supports the...

Microcheck 159

Fever results when macrophages release pro-inflammatory cytokines this occurs when the toll-like receptors on the macrophages are engaged by microbial products. What is an endogenous pyrogen What is an exogenous pyrogen How does fever inhibit the growth of pathogens Syphilis was once treated by intentionally infecting the patient with the parasite that causes malaria, a disease characterized by repeated bouts of fever, shaking, and chills. Why would this treatment cure syphilis

Causative Agent In Morbid Pregnancy-related Outcomes

Figure 16.6 Protective Outcomes of Antibody-Antigen Binding Figure 16.6 Protective Outcomes of Antibody-Antigen Binding is recognized by receptors in the placenta, permitting transport across to the fetus. Since IgG production is not optimal until the secondary response, women who have not been exposed to certain disease-causing agents that can infect and damage the fetus are warned to take extra precautions during pregnancy. For example, pregnant women are advised not to eat raw meat or become...

Viruses and Animal Tumors

As pointed out in the Glimpse of History, viruses were implicated in causing tumors in chickens in the early twentieth century. Retroviruses are the most important tumor viruses in animals, whereas in humans, DNA viruses are the most important. Tumor Viruses and Cell Transformation An understanding of the mechanism by which viruses cause tumors in animals was given a big boost when it was observed that tumor viruses could rapidly change the properties of human cells growing in cell culture....

Using Chemicals to Destroy Microorganisms and Viruses

Germicidal chemicals can be used to disinfect and, in some cases, sterilize. Most chemical germicides react irreversibly with vital enzymes and other proteins, the cytoplasmic membrane, or viral envelopes, although their precise mechanisms of action are often not completely understood (figure 5.6). Although generally less reliable than heat, these chemicals are suitable for treating large surfaces and many heat-sensitive items. Some are sufficiently non-toxic to be used as antiseptics. Those...

Microcheck 146

Most human tumors are not caused by viruses but by mutations in certain genes. The most common viral cause of tumors in humans is DNA tumor viruses. One retrovirus is known to cause a rare human tumor. Name three viruses that cause tumors in humans. Name a tumor common in AIDS patients and the virus that causes it. Why is it not surprising that AIDS patients frequently suffer a viral-induced tumor

Microcheck 215

Mutations and transfer of genetic information have enabled microorganisms to develop resistance to each new antimicrobial drug that has been developed. Drug resistance affects the cost, complications, and outcomes of medical treatment. Slowing the emergence and spread of bacteria involves the cooperation of health care personnel, educators, and the general public. Explain how using a combination of two antimicrobial drugs helps prevent the development of spontaneously resistant mutants. Explain...

Concerns Regarding DNA Technologies

Advent of any new technology should bring scrutiny over the safety and efficacy of the procedures. When recombinant DNA technologies first allowed the cloning of genes over two decades ago, controversies swirled about their use and possible abuse. Even the scientists who developed the technologies were concerned about potential dangers in gene cloning. In response, the National Institutes of Health (NIH) formed the Recombinant DNA Advisory Committee (RAC) to develop a set of guidelines for...

Using Microorganisms to Nourish the World

The world's steadily increasing population mandates the efficient use of finite natural resources and the development of new protein supplies to nourish that growing populace. One potential solution that addresses both of these needs is to cultivate microorganisms as a protein source, employ- ing industrial by-products currently considered wastes as the growth medium. The term single-cell protein or SCP was coined in the 1960s to describe the use of unicellular organisms such as yeast and...

The Cells of the Immune System

The cells of the immune system can move from one part of the body to another, traveling through the body's circulatory systems like vehicles on an extensive interstate highway system. They are always found in normal blood, but their numbers usually increase during infections, recruited from reserves of immature cells that develop in the bone marrow. Some cells play dual functions, having crucial roles in both innate and adaptive immunity. The formation and development of blood cells is called...

Genetically Engineering Eukaryotic Cells

Transferring genes into most eukaryotic cells is considerably more difficult than transferring them into prokaryotic cells. This is particularly true with plant and animal cells. Vectors Used to Transfer DNA into Eukaryotic Cells Like the vectors used for cloning DNA in bacterial cells, vectors used to transfer DNA into eukaryotic cells generally have a selectable marker and a unique restriction enzyme site. Frequently, they also have a characteristic that allows the Bacterial cells plated on...

Micrococcus Species Status Epilepticus

Obligate aerobes generate energy exclusively by respiration. Micrococcus species are Gram-positive cocci found in soil and on dust particles, inanimate objects, and skin. (Figure 11.12) Mycobacterium species are widespread in nature. Although they have a Gram-positive type of cell wall, they stain poorly they are acid-fast. Mycobacterium species cause tuberculosis and Hansen's disease (leprosy). Pseudomonas species are Gram-negative rod-shaped bacteria that are widespread in nature and have...

Interactions of Animal Viruses with Their Hosts

For bacterial viruses, the host organism is a single cell, and so other kinds of cells do not affect the course of the infection. In the case of animals, however, the outcome of viral infection depends on many factors that are independent of the infected cell. Of special importance are the defense mechanisms of the host, such as the presence of protective antibodies that can confer immunity against a virus ordinarily lethal to an individual without such immunity. Devastating epidemics of...

Bacteria that Derive Nutrients from Other Organisms

Bacteria Cycle Atacting

Some bacteria obtain nutrients directly from other organisms. Bdellovibrio species do this by preying on other bacteria, attacking them and digesting their contents, eventually killing them. Bioluminescent bacteria use another tactic they have established relationships with fish and squid in which the animal provides nutrients and protection while the bacterium provides a source of luminescence. Legionella species can live intracellularly within the protected confines of protozoa. Bdellovibrio...

Sterilization Using Pressurized Steam

Pressure cookers and their commercial counterpart, the autoclave, heat water in an enclosed vessel that achieves temperatures above 100 C (figure 5.3). As heated water in the vessel forms steam, the steam causes the pressure in the vessel to increase beyond atmospheric pressure. The higher pressure, in turn, increases the temperature at which steam forms. Whereas steam produced at atmospheric pressure never exceeds 100 C, steam produced at an additional 15 psi (pounds square inch) is 121 C, a...

Microcheck 246

Rotaviruses are the leading cause of viral gastroenteritis in infants and children, and they also are a common cause of traveler's diarrhea. Norwalk viruses cause almost half the viral gastroenteritis in children and adults. Hepatitis A is transmitted by the fecal-oral route and is preventable by gamma globulin and an inactivated vaccine. Hepatitis B, transmitted by exposure to blood and by sexual intercourse, is preventable by a vaccine produced in yeast. A combination hepatitis A and...

Microcheck 245

Vibrios, Campylobacter jejuni, and enterobacteria account for most intestinal bacterial infections. Pathogenic mechanisms include attachment, toxin production, cell invasion, and destruction of microvilli. Gastroenteritis can be caused either by infectious microorganisms consumed with the food or by toxic products of microbial growth in food. Some microbial toxins alter the secretory function of cells in the small intestine without killing or visibly damaging them. Unsuspected human carriers...

Gram Negative Septicemia

Septicemia is a common nosocomial illness, with an estimated 400,000 cases occurring in the United States each year. Approximately 30 of of the cases are caused by Gram-negative bacteria. Endotoxin release by Gram-negative bacteria can lead to shock and death. The symptoms of septicemia include violent shaking chills and fever, often accompanied by anxiety and rapid breathing. If septic shock develops, urine output drops, the respirations and pulse become more rapid, and the arms and legs...

Overview of the Innate Defenses

First-line defenses are the barriers that separate and shield the interior of the body from the surrounding environment they are the initial obstacles that microorganisms must overcome to invade the tissues. The anatomical barriers, which include the skin and mucous membranes, not only provide physical separation, but they are often bathed in secretions containing substances that have antimicrobial properties (figure 15.1). Characteristics of the components of innate immunity, including the...

Characteristics to Identify Prokaryotes

Increasingly, genotypic characteristics are being used to identify microorganisms, particularly those that are difficult to cultivate. DNA probes and polymerase chain reaction (PCR) can both be used to detect nucleotide sequences that are unique to a given organism. DNA sequencing has made identification possible of organisms that cannot be grown in culture. nucleic acid probe, pp. 225,236 polymerase chain reaction, pp. 229,239 sequencing, pp. 229,237 Nucleic Acid Probes to Detect Specific...

Membrane Bound Organelles

The presence of membrane-bound organelles is an important feature that sets eukaryotic cells apart from their prokaryotic counterparts. The predominant distinguishing feature of the eukaryotic cell is the nucleus, which contains the DNA. Enclosing this structure are two concentric lipid bilayer membranes the inner membrane and the outer membrane. These membranes make up the nuclear envelope. Spanning the membranes are complex protein structures that form nuclear pores, allowing large molecules...

Examples of Emerging Antimicrobial Resistance

Some of the problems associated with the increasing resistance of bacteria to antimicrobial drugs are highlighted by the following examples. One of the most dramatic examples of antimicrobial resistance is the enterococci, a group of bacteria that are part of the normal intestinal flora and a common cause of nosocomial infections. Enterococci are intrinsically less susceptible to many common antimicrobials. For example, their penicillin-binding proteins have low affinity for certain b-lactam...

Methanogens Often Grow In Association With

Methanogens are found in anaerobic environments where hydrogen gas and carbon dioxide are available. Because these gases are generated by chemoorganotrophs during the fermentation of organic material, methanogens often grow in association with these microorganisms. Methanogens, however, are generally not found in environments that contain high levels of sulfate, nitrate, or other inorganic electron acceptors. This is because microorganisms that oxidize hydrogen gas using these electron...

Review Q

Describe three types of symbiotic relationships. 2. Describe two situations that can lead to changes in the composition of the normal flora. 3. What is the difference between acute, chronic, and latent disease 4. Why are Koch's Postulates not sufficient to establish the cause of all infectious diseases 5. Describe the four general mechanisms by which microorganisms cause disease. 6. Describe two mechanisms that bacteria use to invade mucous membranes. 7. Explain how capsules enable an organism...

A B C D E

370 Chapter 14 Viruses, Prions, and Viroids Infectious Agents of Animals and Plants Applications 1. You are a scientist at a pharmaceutical company in charge of developing drugs against HIV. Discuss four possible targets for drugs that might be effective against this virus. 2. Researchers debate the evolutionary value to the virus of its ability to cause disease. Many argue that viruses accidentally cause disease and only in animals that are not the natural host. They state that this strategy...

Anaerobic Chemoorganotrophs Anaerobic Respiration

Chemoorganotrophs oxidize organic compounds such as glucose to obtain energy. Like the chemolithotrophs, chemoorgan-otrophs that grow anaerobically employ a terminal electron acceptor other than O2. Sulfur and sulfate are common inorganic compounds used as a terminal electron acceptor by these organisms. Sulfur- and Sulfate-Reducing Bacteria When sulfur compounds are used as a terminal electron acceptor, they become reduced to form hydrogen sulfide, the compound responsible for the rotten-egg...

Approaches to Control

The processes used to control microorganisms are either physical or chemical, though a combination of both may be used. Physical methods include heat treatment, irradiation, filtration, and mechanical removal (washing). Chemical methods use any one of a variety of antimicrobial chemicals. The method chosen depends on the circumstances and resulting degree of control required. Definitions related to microbial control are summarized in table 5.1. The process of removing or destroying all...

Dynamics of Prokaryotic Growth

M he greatest contributor to methods of culturing bacte-t ria was Robert Koch (1843-1910), a German physician who combined a medical practice with a productive research career for which he received a Nobel Prize in 1905. Koch was primarily interested in identifying disease-causing bacteria. To do this, however, he soon realized it was necessary to have simple methods to isolate and grow these particular species. He recognized that a single bacterial cell could multiply on a solid medium in a...

The Microbial World

The microbial world includes the kinds of cells that van Leeuwenhoek observed looking through his simple microscope (figure 1.4). Although he could not realize it at the time, the microbial world, in fact all living organisms, can be classified into one of three major groups called domains. Organisms in each domain share properties of their cells that distinguish them from members of the other domains. Many properties, however, are shared among members of different domains because genes were...

The Blueprint of Life from DNA to Protein

T n 1866, the Czech monk Gregor Mendel showed that traits rn are inherited by means of physical units, which we now call * genes. It was not until 1941, however, that the precise function of genes was revealed when George Beadle, a geneticist, and Edward Tatum, a chemist, published a scientific paper reporting that genes determine the structure of enzymes. Biochemists had already shown that enzymes catalyze the conversion of one compound into another in a biochemical pathway. Beadle and Tatum...

Algae

The algae are a diverse group of eukaryotic organisms that share some fundamental characteristics but are not related on the phy-logenetic tree. These organisms are studied by algologists in a field known as algology. Algae are organisms that use light energy to convert CO2 and H2O to carbohydrates and other cellular products with the release of oxygen. Algae contain chlorophyll a, which is necessary for photosynthesis. In addition, many algae contain other pigments that extend the range of...

Reviewers of the Fourth Edition

Gene Nester, Evans Roberts, and Nancy Pearsall shared a vision many years ago to write a new breed of microbiology textbook especially for students planning to enter nursing and other health-related careers. Today there are other books of this type, but we were extremely gratified to learn that 85 of the students we surveyed intend to keep their copies of Microbiology A Human Perspective because they feel it will benefit them greatly as they pursue their studies in these fields. We offer...

Environmental Factors that Influence Microbial Growth

As a group, prokaryotes inhabit nearly every environment on earth. Many live in habitats that humans consider quite com- Figure 4.4 Temperature Requirements for Growth Prokaryotes are commonly divided into five groups based on their optimum growth temperatures.This graph depicts the typical temperature ranges of these groups. Note that the optimum temperature, the point at which the growth rate is highest, is near the upper limit of the range. Figure 4.4 Temperature Requirements for Growth...

Normal Flora of the Genitourinary System

Normally, the urine and urinary tract above the entrance to the bladder are essentially free of microorganisms the lower urethra, however, has a normal resident flora. Species of Lactobacillus, Staphylococcus (coagulase-negative), Corynebacterium, Haemophilus, Streptococcus, and Bacteroides are common inhabitants. The normal flora of the genital tract of women is influenced by the action of estrogen hormones on the epithelial cells of the vaginal mucosa. When estrogens are present, glycogen is...

Normal Flora

The normal flora is important in protecting the body against invasion by pathogens. This section focuses mainly on flora of the oral cavity and intestine. The esophagus has a relatively sparse population, consisting mostly of bacteria from the mouth and upper respiratory tract. When empty of food, the normal stomach is devoid of microorganisms because they are killed by the action of acid and pepsin. normal flora, pp. 375,461 Of all the species of bacteria introduced into the mouth from the...

Mechanisms of Action of Antibacterial Drugs

A number of bacterial processes utilize enzymes or structures that are either different, absent, or not commonly found in eukary-otic cells. Several microbial processes, including the synthesis of bacterial cell walls, proteins, and nucleic acids, metabolic path- 21.3 Mechanisms of Action of Antibacterial Drugs 511 21.3 Mechanisms of Action of Antibacterial Drugs 511 Metabolic Pathways (folate biosynthesis) Metabolic Pathways (folate biosynthesis) Figure 21.2 Targets of Antibacterial...

Filamentous Protein Appendages

Many bacteria have protein appendages that are anchored in the membrane and protrude out from the surface. These structures are not essential to the life of the cell, but they do allow some bacteria to exist in certain environments in which they otherwise might not survive. The flagellum is a long protein structure responsible for most types of bacterial motility (figure 3.38). By spinning like a propeller, using proton motive force as energy, the flagellum pushes the bacterium through liquid...

Virus Interactions with Host Cells

Animal and bacterial viruses interact with their host cells in several different ways. Some viruses take over the metabolism of the host cell completely with resulting lysis of the cell. An example is the phage T4, which infects E. coli. Others use the host cells' enzymes and metabolic machinery while the host cell continues to multiply and the virions leak out of the cell. Examples are the filamentous phages. Other viruses live in harmony with the host cell and multiply as the host cell...

Nutritional Factors that Influence Microbial Growth

Growth of any bacterium depends not only on a suitable physical environment, but also an available source of chemicals to use as nutrients. From these, the cell must synthesize all of the cell components discussed in chapter 3, including lipid membranes, cell walls, proteins, and nucleic acids. These components are made from building blocks such as fatty acids, sugars, amino Table 4.3 Representative Functions of the Major Elements Component of cellular constituents including amino acids,...

Mechanisms Of Pathogenesis

From a microbe's perspective, the interior of the human body is a lucrative source of nutrients, provided that some of the obstacles of the innate and adaptive immune systems can be overcome. The ability to subvert these defenses and cause damage is what separates the pathogenic microbes from the multitudes of other microorganisms that inhabit this planet. The methods that disease-causing microbes use to either evade the host defenses or cause damage are called mechanisms of patho-genicity. The...

Pickled Vegetables

Another fermentation process known as pickling originated as a way to preserve vegetables such as cucumbers and cabbage. Today, pickled products such as sauerkraut (cabbage), pickles (cucumbers), and olives are valued for their flavor. Unlike the fermentation of milk products that rely on the use of starter cultures in the manufacturing process, fermentation of most vegetables utilizes naturally occurring lactic acid bacteria residing on the vegetables. One of the most well-studied natural...

T Lymphocytes Antigen Recognition and Response

T lymphocytes, or T cells, share several important characteristics with B cells and, in fact, are identical in appearance microscopically. Like the B cells, T cells have multiple copies of a receptor on their surface that recognizes a specific antigen. The T-cell receptor (TCR) consists of two polypeptide chains, designated alpha (a) and beta (b), each with a variable and constant region (figure 16.15). As in the B-cell receptor, the variable regions supply the antigen-binding sites. The...

Trends in Disease

The rapid scientific advances made over the past several decades led some people to speculate at one point that the war against infectious diseases, particularly those caused by bacteria, had Figure 20.9 A Case of Smallpox, a Disease that Has Now Been Eradicated Figure 20.9 A Case of Smallpox, a Disease that Has Now Been Eradicated been won. Microorganisms have occupied this planet far longer than have humans, however, evolving to occupy every habitat having the potential for life, including...

A 5s B 16s

All of these are commonly used. 10. Which of the following statements is false A. Tropheryma whippelii could be identified before it had been grown in culture. B. The GC content of DNA can be measured by determining the temperature at which double-stranded DNA melts. C. Sequence differences between organisms can be viewed as an evolutionary chronometer to assess their relatedness. D. Based on DNA homology studies, members of the genus Shigella should be in the same species as...

Bacteria that Form Storage Granules

A number of aquatic bacteria form granules that serve to store nutrients. Recall that anoxygenic phototrophs often store sulfur granules, which can later be used as a source of electrons for reducing power. Some bacteria store phosphate, and others store compounds that can be used to generate ATP. Members of the genus Spirillum are Gram-negative spiral-shaped, microaerophilic bacteria. Spirillum volutans forms volutin granules, which are storage forms of phosphate. These are sometimes called...

Non Venereal Genital System Diseases

The genital tract is the portal of entry for numerous infectious diseases, both venereal and non-venereal (venereal, from Venus, the goddess of love non-venereal means not transmitted by making love). This section discusses some examples of non-venereal genital diseases. The term venereal disease (VD), formerly meaning disease transmitted almost exclusively by sexual intercourse, is now often used interchangeably with sexually transmitted disease (STD), which includes all diseases spread by...

German Measles Rubella

German measles and three-day measles are common names for rubella. The term German measles arose because the disease was first described in Germany. In contrast to varicella and rubeola, rubella is typically a mild, often unrecognized disease that is difficult to diagnose. Nevertheless, infection of pregnant women can have tragic consequences. Characteristic symptoms of German measles are slight fever, mild cold symptoms, and enlarged lymph nodes behind the ears and on the back of the neck....

What Is The Benefit Of Using Covalent Bonds As A Mean Of Attaching To Surfaces

A bilayer is associated with A. proteins. D. complex polysaccharides. 10. Isomers are associated with 1. carbohydates. 2. amino acids. 4. RNA. 5. fatty acids. 1. A group of bacteria known as thermophiles thrive at high temperatures that would normally destroy other bacteria. Yet these thermophiles cannot survive well at the lower temperatures normally found on the earth. Propose a plausible explanation for this observation. 2. Microorganisms use hydrogen bonds to attach themselves to the...

Malaria

Malaria is an ancient scourge, as evidenced by early Chinese and Hindu writings. During the fourth century B.C., the Greeks noticed its association with exposure to swamps and began drainage projects to control the disease. The Italians gave the disease its name, malaria, which means bad air, in the seventeenth century. In early times, malaria ranged as far north as Siberia and as far south as Argentina. In 1902, Ronald Ross received a Nobel Prize for demonstrating the life cycle of the...

Atp

Figure 6.17 Electron Transport Energy is released as electrons are passed along carriers of the electron transport chain. Figure 6.17 Electron Transport Energy is released as electrons are passed along carriers of the electron transport chain. these processes is that protons are pumped to the other side of the membrane, establishing the concentration gradient across the membrane. Most carriers of the electron transport chain are grouped into several large protein complexes that function as...

Autoimmune Diseases

Usually, the body's immune system recognizes its self-antigens and deletes clones of cells that would respond and attack its own tissues. A growing number of diseases are suspected of being caused by an autoimmune process, however, meaning that the immune system of the body is responding to the tissues of the body as if they are foreign. Some of these diseases are listed in table 18.4. Susceptibility to many of them is influenced by the major histocompatibility makeup of the patient, and so,...