UNIT 8: VIRUSES AND BACTERIA (STUDY GUIDE)
Terms in this set (52)
3 ways to protect from viral infection
•Use of vaccines,
•Stay away from sick people;
Are viruses living/nonliving?
Why are viruses considered nonliving?
They are noncellular particles made up of genetic material that is not activated until injected into a host cell.
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.
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).
Infect a cell and produce a DNA copy of the virus' RNA.
2 examples of a retrovirus
HIV, human T cell leukemia virus
Why is it so difficult to produce a vaccine for a retrovirus?
RNA doesn't have the same proofreading mechanism as DNA, so mutations accumulate quickly;
(Ex: why we need a new flu shot every year).
What is HIV? How does it infect humans? Which cells are targeted?
•Human immunodeficiency virus;
•Infects helper T cells;
•Eventually, white blood cell count drops too low and AIDS develops.
Helper T cells as related to white blood cells...
Lymphocytes that are a kind of white blood cell.
Preparation of weakened or killed virus that stimulates the immune system to defend against the real virus in the future.
5 examples of viral diseases
Common cold, influenza, AIDS, chicken pox, and West Nile virus
Bacteria reproduce asexually by a process known as ---.
Some bacteria have a primitive form of sexual reproduction known as CONJUNCTION. Describe what happens in the process.
A hollow tube forms between two cells and they exchange genetic material.
•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).
•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;
4 ways in which bacteria are useful to the environment or humans
•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.
3 ways in which bacterial diseases can be transmitted
•Airborne: respiratory droplets (sneezing, coughing);
5 examples of bacterial diseases
Lyme disease, tuberculosis, strep throat, tetanus, cholera
2 ways that bacteria cause the symptoms of disease
•Damaging host tissues;
List 5 methods used to control bacterial growth
Physical removal, disinfectants, food storage, food processing, sterilization by heat
How are bacterial diseases treated?
Give two examples of pathogens
(As well as prion, protozoa, viroid, fungi, parasite)
•Don't target specific disease; wide range;
•1st and 2nd line of defense;
(Skin, mucus, fever).
•Attack particular pathogen; targeted response;
•3rd line of defense;
(Involves B and T cells).
Substance that sends the immune system into action.
Proteins produced to target a specific antigen and tags it for destruction; shape of antibody fits shape of antigen (lock and key): humoral.
Traps pathogens in the nose and throat.
Increases body temperature to slow the growth of pathogens.
Inhibits the making of viral proteins and helps block viral replication.
Push pathogens away from lungs.
Increases flow of white blood cells and fluids to an area.
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.
The branch of acquired immunity that involves the activation of cytotoxic T cells, which defend against infected cells; cell eats the antigen.
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?
Vaccines don't respond to antibiotics, so using them when it's not necessary can contribute to bacterial resistance.
•Body FORMS antibodies from exposure to pathogen;
•Body GIVEN antibodies from the memory cells of another person;
3 ways to prevent the spread of infectious disease.
Vaccination, washing hands, clean water
Both viruses and bacteria are infectious diseases; true/false.
New disease that appears or an old one that reappears.
Describe 2 reasons we are seeing an emergence of new diseases, or the re-emergence of diseases that were once completely gone.
1) Changing interactions with animals (converging habitats, exotic animal trade);
2) Misuse of medications (bacterial resistance).
Type of virus that infects bacterial cells
Prokaryotes that synthesize methane from carbon dioxide and hydrogen gas.
Spiral shaped bacteria
Rod shaped bacteria
All bacteria are classified as ---.
Why are antibiotics only effective for bacterial infections, not viral infections?
Antibiotics destroy the call wall of the bacteria, but viruses only infect body cells, which have no cell wall to destroy.
Any change, other than an injury, that causes a change in the normal function of the body system is called a ---.
A strong response by the immune system to a harmless antigen is called an ---.
Antigen vs. pathogen
•Antigen: substance that triggers the response of an antibody;
•Pathogen: disease-causing agent.