UNIT 8: VIRUSES AND BACTERIA (STUDY GUIDE) – Flashcards
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Lysogenic Cycle
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1) Integrated into the cell's chromosome; 2) Cells replicate with the virus that is passed on (may remain dormant, but could activate at any time, prompting the lytic cycle).
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Retrovirus
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Infect a cell and produce a DNA copy of the virus' RNA.
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2 examples of a retrovirus
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HIV, human T cell leukemia virus
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Why is it so difficult to produce a vaccine for a retrovirus?
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RNA doesn't have the same proofreading mechanism as DNA, so mutations accumulate quickly; (Ex: why we need a new flu shot every year).
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What is HIV? How does it infect humans? Which cells are targeted?
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•Human immunodeficiency virus; •Infects helper T cells; •Eventually, white blood cell count drops too low and AIDS develops.
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Helper T cells as related to white blood cells...
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Lymphocytes that are a kind of white blood cell.
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Vaccine
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Preparation of weakened or killed virus that stimulates the immune system to defend against the real virus in the future.
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5 examples of viral diseases
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Common cold, influenza, AIDS, chicken pox, and West Nile virus
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Bacteria reproduce asexually by a process known as ---.
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binary fission
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Some bacteria have a primitive form of sexual reproduction known as CONJUNCTION. Describe what happens in the process.
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A hollow tube forms between two cells and they exchange genetic material.
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Bacteria (domain)
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•More species than archaea; •Live almost anywhere (fresh/salt water, land, on and within humans/other eukaryotes); •Usually surrounded by cell wall containing peptidoglycan; (Ex: E. coli).
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Archaea (domain)
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•Looks very similar to Bacteria domain (equally small, lack nucleus, have cell walls); •Lack peptidoglycan and the DNA sequences are more like eukaryotes than bacteria; •Live in extremely harsh environments; (Ex: anaerobes).
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4 ways in which bacteria are useful to the environment or humans
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•Decompose dead organisms to supply raw material; •Produce energy that food chains everywhere are dependent on; •Converts atmospheric nitrogen to nitrogen used by organisms; •Produce foods, remove human waste and poisons from water.
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3 ways in which bacterial diseases can be transmitted
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•Airborne: respiratory droplets (sneezing, coughing); •Physical contact; •Food/water contamination.
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5 examples of bacterial diseases
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Lyme disease, tuberculosis, strep throat, tetanus, cholera
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2 ways that bacteria cause the symptoms of disease
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•Damaging host tissues; •Releasing toxins.
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List 5 methods used to control bacterial growth
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Physical removal, disinfectants, food storage, food processing, sterilization by heat
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How are bacterial diseases treated?
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Antibiotics
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Pathogen
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Disease-causing agent
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Give two examples of pathogens
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Bacteria, virus (As well as prion, protozoa, viroid, fungi, parasite)
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Nonspecific Defense
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•Don't target specific disease; wide range; •1st and 2nd line of defense; (Skin, mucus, fever).
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Specific Defense
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•Attack particular pathogen; targeted response; •3rd line of defense; (Involves B and T cells).
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Antigen
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Substance that sends the immune system into action.
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Antibody
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Proteins produced to target a specific antigen and tags it for destruction; shape of antibody fits shape of antigen (lock and key): humoral.
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Mucus
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Traps pathogens in the nose and throat.
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Fever
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Increases body temperature to slow the growth of pathogens.
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Interferon
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Inhibits the making of viral proteins and helps block viral replication.
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Cilia
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Push pathogens away from lungs.
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Inflammatory Response
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Increases flow of white blood cells and fluids to an area.
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Humoral Response
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The branch of acquired immunity that involves the activation of B cells and that leads to the production of antibodies, which destroy antigens using "lock and key"; in body fluids/bloodstream.
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Cell-Mediated Response
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The branch of acquired immunity that involves the activation of cytotoxic T cells, which defend against infected cells; cell eats the antigen.
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It is not always easy to determine if a patient has a bacterial infection or a viral infection. How could this contribute to the misuse of medications?
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Vaccines don't respond to antibiotics, so using them when it's not necessary can contribute to bacterial resistance.
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Active Immunity
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•Body FORMS antibodies from exposure to pathogen; •Long lived.
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Passive Immunity
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•Body GIVEN antibodies from the memory cells of another person; •Short lived.
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3 ways to prevent the spread of infectious disease.
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Vaccination, washing hands, clean water
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Both viruses and bacteria are infectious diseases; true/false.
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True
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Emerging Disease
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New disease that appears or an old one that reappears.
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Describe 2 reasons we are seeing an emergence of new diseases, or the re-emergence of diseases that were once completely gone.
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1) Changing interactions with animals (converging habitats, exotic animal trade); 2) Misuse of medications (bacterial resistance).
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Type of virus that infects bacterial cells
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Bacteriophage
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Cocci
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Spherical bacteria
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Methanogens
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Prokaryotes that synthesize methane from carbon dioxide and hydrogen gas.
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Spirilli
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Spiral shaped bacteria
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Bacilli
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Rod shaped bacteria
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All bacteria are classified as ---.
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Prokaryotes
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Why are antibiotics only effective for bacterial infections, not viral infections?
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Antibiotics destroy the call wall of the bacteria, but viruses only infect body cells, which have no cell wall to destroy.
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Any change, other than an injury, that causes a change in the normal function of the body system is called a ---.
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Disease
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A strong response by the immune system to a harmless antigen is called an ---.
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Allergy
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Antigen vs. pathogen
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•Antigen: substance that triggers the response of an antibody; •Pathogen: disease-causing agent.
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