front 1 The degree of pathogenicity | back 1 Virulence |
front 2 What are the three portals of entry for pathogens? | back 2 Mucous membranes, the skin, and the parenteral route. |
front 3 What is the easiest and most frequently traveled portal of entry for infectious microorganisms? | back 3 Mucous membranes. |
front 4 What mucous membranes can bacteria and viruses use to enter the body? | back 4 Respiratory tract, gastrointestinal tract, genitourinary tract, conjunctiva. |
front 5 Most enter through the mucous membranes of which tracts? | back 5 Gastrointestinal and respiratory. |
front 6 How do microorganisms gain access to the gastrointestinal tract? | back 6 In food and water and via contaminated fingers. |
front 7 T or F: Most microbes that enter the body in these ways are destroyed by hydrochloric acid and enzymes in the stomach or by bile and enzymes in the small intestines. | back 7 True. |
front 8 The genitourinary tract is the portal of entry for which types of pathogens? | back 8 Those contracted sexually. |
front 9 T or F: If a pathogen gains entry into the body by another portal of entry than is preferred, they may not cause disease. | back 9 True. |
front 10 T or F: The number of microbes invading the body may determine whether they cause disease. | back 10 True; if only a small number of microbes enter the body, they will probably be overcome by the host's defenses. |
front 11 The virulence of a microbe is often expressed as | back 11 the ID50 or the infectious dose for 50% of the sample population. |
front 12 The potency of a toxin is often expressed as the | back 12 LD50 or the lethal dose for 50% of a sample population. |
front 13 How do pathogens attach to the host? | back 13 Via adhesions or ligands that bind specifically to certain receptors. |
front 14 Where are adhesions located? | back 14 On a microbe's glycocalyx or on other microbial surface structures, such as pili, fimbriae, and flagella. |
front 15 The ability for microbes to come together in masses, cling to surfaces, and take in and share available nutrients is called what? An example is dental plaque. | back 15 Biofilms. |
front 16 The ability for a pathogen to alter its surface antigens. | back 16 Antigenic variation |
front 17 How do some pathogens obtain iron? | back 17 By secreting proteins called siderophores. |
front 18 How do siderophores work? | back 18 They are released into the medium, where they take the iron away from iron-transport proteins by binding the iron even more tightly. |
front 19 Produced inside some bacteria as part of their growth and metabolism and are secreted by the bacterium into the surrounding medium or released following lysis. | back 19 Exotoxins |
front 20 T or F: Bacteria that produce exotoxins may be gram-positive or gram-negative. | back 20 True. |
front 21 What are toxoids? | back 21 Inactivated exotoxins used in vaccines. |
front 22 Antibodies against specific exotoxins are called | back 22 Antitoxins |
front 23 How do exotoxins work? | back 23 They destroy particular parts of the host's cells or by inhibiting certain metabolic functions. |
front 24 T or F: Exotoxins are disease specific. | back 24 True. This means exotoxins produce the signs and symptoms of diseases, not the bacteria itself. |
front 25 What are the three types of exotoxins? | back 25 A-B toxins, membrane-disrupting toxins, and superantigens. |
front 26 Most exotoxins are what type? | back 26 A-B toxins |
front 27 What does A-B toxin mean? | back 27 It means there are two parts. Part A is made up of an active (enzyme) component and Part B is the binding component. |
front 28 How does membrane-disrupting toxins contribute to virulence? | back 28 They kill host cells, especially phagocytes, and by aiding the escape of bacteria from sacs within phagocytes into the host cell's cytoplasm. |
front 29 What does membrane-disrupting toxins cause? | back 29 Lysis of the host cell. |
front 30 Membrane-disrupting toxins that kill phagocytic leukocytes are called | back 30 Leukocidins |
front 31 Toxins that kill erythrocytes (red blood cells) by forming protein channels are called | back 31 Hemolysins. |
front 32 Hemolysins produced by streptococci are called | back 32 Streptolysins |
front 33 Antigens that provoke a very intense immune response due to the release of cytokines from host cells (T cells) | back 33 Superantigens |
front 34 Some gram-negative bacteria produce toxins which damage DNA, such as mutations, disrupting cell divisions, and leading to cancer, called | back 34 Genotoxins |
front 35 What are some examples of exotoxins? | back 35 A-B Toxin: Botulism, Diphtheria, Anthrax, Tetanus Membrane-Disrupting: Gas gangrene and food poisoning, antibiotic-associated diarrhea Superantigen: Food poisoning, Toxic shock syndrome Genotoxin: Stomach cancer |
front 36 Where are endotoxins located? | back 36 Within the bacterial cell on the LPS portion of gram-negative bacteria. |
front 37 The lipid portion of LPS is called | back 37 Lipid A |
front 38 Endotoxins are _______, whereas exotoxins are ________. | back 38 Lipopolysaccharides, proteins |
front 39 When are endotoxins released? | back 39 During bacterial multiplication and when gram-negative bacteria die. |
front 40 What signs and symptoms do endotoxins produce and how are they different from exotoxins? | back 40 Chills, fever, weakness, generalized aches, and in some cases, shock and even death. They are different because endotoxins produce the same signs and symptoms, with varying degree, regardless of the species of microorganism. Exotoxins are specific for a particular cell structure. |
front 41 A consequence of endotoxins is the activation of blood clotting proteins, causing the formation of small blood clots, known as | back 41 disseminated intravascular coagulation. |
front 42 Which toxin comes from mostly gram-positive bacteria? | back 42 Exotoxins. |
front 43 Endotoxins come from what kind of bacteria? | back 43 Gram-negative. |
front 44 Which toxin has a higher heat stability? | back 44 Endotoxins, which can withstand autoclaving (121C for 1
hour) |
front 45 Which toxin has a low ability to cause disease? | back 45 Endotoxins, whereas exotoxins are high. |
front 46 Do exotoxins produce fevers? | back 46 No. |
front 47 Are endotoxins easily neutralized by antibodies? | back 47 No, therefore, effective toxoids cannot be made to immunize against toxin. |
front 48 An outcome of lysogeny that changes the characteristics of a microbe due to the incorporation of a prophage is called | back 48 Lysogenic conversion |
front 49 What is a result of lysogenic conversion? | back 49 The bacterial cell is immune to infection by the same type of phage. |
front 50 The visible effects of viral infection on a cell are known as | back 50 cytopathic effects. |