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3 ways to protect from viral infection

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•Use of vaccines, •Stay away from sick people; •Safe practices.

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Are viruses living/nonliving?

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Nonliving

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Why are viruses considered nonliving?

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They are noncellular particles made up of genetic material that is not activated until injected into a host cell.

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Lytic Cycle

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1) Take over the cell's machinery and hijacks it to transcribe the viral gene (using its own functions to make thousands of new viruses); 2) Cells lyse (burst), allowing viral particles to escape.

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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.

UNIT 8: VIRUSES AND BACTERIA (STUDY GUIDE) – Flashcards

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