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| Question | Answer |
| FOCUS 3. During the second half of the nineteenth century, the work of Pasteur and Koch and other scientists stimulated the search for microbes as causes of disease | :) |
| Define antibiotics: | Antimicrobial agent made from microorganisms, and can kill and inhibit the growth of microorganisms, especially those that are infectious or disease-causing |
| > Syllabus point: Describe the contribution of Pasteur and Koch to our understanding of infectious diseases | :) |
| True or False: Louis Pasteur and Robert Koch got along very well together. | False, they did not get along. |
| What did Louis Pasteur and Robert Koch contribute to microbiology? | - Understanding of infectious diseases |
| What was the commonly held belief as the cause for infectious disease, before the work of Louis Pasteur and Robert Koch? | Spontaneous Generation: that organisms emerged spontaneously from non-living things. |
| True or false: Spontaneous generation is a theory. | FALSE: IT IS A COMMONLY HELD BELIEF AND IDEA. |
| What did Louis Pasteur disprove? | The idea of spontaneous generation. |
| What theory did Louis Pasteur establish? | Germ theory of disease |
| What did the germ theory of disease state? | - Germs (micro-organisms) cause disease and emerge from existing microorganisms. |
| How did he discover this? | Fermentation of beet juice - Discovered microbes called yeast - Other microbes responsible for souring of beer/wine/vinegar |
| What was his solution to spoilage caused by microbes? | - Heat substance enough to kill bacteria after fermentation. |
| What did he discover? Hint: it has to do with his name. | Pasteurisation. |
| How did this contribute to microbiology. | -Refuted spontaneous generation idea - Understanding of infectious disease. |
| What experiment did Louis Pasteur conduct? | Swan neck flask experiment. |
| Describe the swan neck flask experiment. | - Swan necked flasks -- necks were not sealed. - He boiled meat broth and as it cooled = drew air from outside. - Microbes from outside stuck in the neck, unable to reach meat. No observation of microbes or bacteria in broth. - If neck broken off --- exposed--> resulted in bacterial growth. - If flask was tilted to allow fluid to reach the neck where microbes were = bacterial growth. |
| What did this prove? | - Organisms which contaminated broth = carried in air. - Therefore, disproved spontaneous generation. |
| What did Louis Pasteur's swan neck experiment show in relation to air and microbes? | The air itself did not cause decay but the microbes in the air did. |
| What did Robert Koch do? | Contribute to microbiology with bacteriological techniques --agar plates. |
| What experiment did Robert Koch conduct? | He examined blood of sheep with anthrax and observed a rod-shaped bacteria = grew this in agar plates -- injected into healthy sheep which then developed anthrax = showed that disease causing agents were from outside the body = supported 'germ theory of disease' |
| What did Robert Koch determine about specific microorganisms? | Specific microorganisms cause specific disease |
| What are 'Koch's Postulates' used to identify? | Specific microorganism that caused disease. |
| List 'Koch's Postulates' | - Microorganism must be in all cases of disease - Can isolate and grow the pathogen in pure culture. - When injected into healthy species -->cause the same disease. - When re-isolated, must be the pure culture pathogen. |
| What is an example of a disease that Robert Koch discovered? | Mycobacterium tuberculosis --> cause of tuberculosis. |
| > Syllabus point: Perform an investigation to model Pasteur’s experiment to identify the role of microbes in decay | :) |
| What was the aim of the experiment conducted to determine that microbes caused decay? | Aim: To model Pasteur's experiment to prove that microbes caused decay. |
| Identify the apparatus in this experiment: | - 2 conical flasks - 1 stopper w/ straight glass tube - 1 stopper w/ s-shaped glass tube (or a rubber tube attached with a bull clip) - Nutrient broth - Beaker - Measuring cylinder - Tape and labels - Bunsen burner - Tripod - Gauze mat - Hot hands heat glove - Tongs |
| Describe the experiment: | 1) 100ml of nutrient broth into conical flasks using measuring cylinder 2) Place straight glass tube with stopper in Flask A and s-shaped one in flask B 3) Boil vigorously for 5mins 4) Remove flask (gloves)--allow cool 5) Label flasks A & B 6) Observe results in both flasks over 10 days 7) Repeat experiment |
| Provide a risk assessment: | - Hot equipment + bunsen burner = burns = gloves, goggles, let cool before labelling - technique for placing stopper on flask: steam can cause burns = use tongs - Broken glassware - don't use hands --> |
| Identify the independent variable: | - one glass rube had rubber tubing |
| Identify the dependent variable: | Presence of microbes (NOT PATHOGENS): smell bacteria as they can't be seen in liquid. |
| Identify controlled variable: | - Same nutrient broth - Same amount of broth - Boiled for same time - Same equipment - Same environment. |
| What were the results? | - Uncovered glass = grew large colonies of fungi. - Liquid: bubbled, scum, cloudy, odour - S-shaped tube: unchanged. |
| How could you improve validity? | - It was a simulation of Pasteur's experiment = copying exactly = more valid. |
| > Syllabus point: Distinguish between: prions, viruses, bacteria, protozoans, fungi, macro-parasites and name one example of a disease caused by each type of pathogen | :) |
| What is a non-cellular life? | - Life that exists without a cell structure |
| What is a cellular life? | - Life with cell stucture |
| What is a eucaryote? | Cell with: - Nucleus - Membrane bound organelles |
| What is a procaryote? | Cell with - No nucleus - No membrane bound organelles |
| What is a prion? | - Non living malformed protein which has stopped functioning. - DO NOT contain genetic material - Non cellular (no cell structure) - Can cause other proteins to become abnormal - Prion diseases = due to degeneration of brain tissues (tissues full of holes) - Can be infectious (by eating contaminated tissues), transmitted through medical surgery (brain), heredity. |
| Provide a examples of diseases caused by a prion pathogen: | Creutzfeldt-Jakob disease (CJD) - HUMAN and Bovine spongiform encephelopathy in cattle (BSE/mad cow disease) |
| Are prions always bad? | No, they are used by the brain for communication but malfunctioning prions can covert good prions. |
| Explain how viruses cause disease: | - Virus: non cellular - Protein coat (contains genetic information) - Reproduce by taking over host cell - injecting nucleic acid + make more copies = host cell bursts = spreads virus = no cure, only vaccination to reduce incidence. |
| Provide examples of diseases caused by viruses: | - Aids - Measles - Chicken Pox - Mumps - Herpes - Hepatitis - Glandular fever - Common cold |
| True or false: Viruses destroy bacteria in the processes in the body. | True. |
| Describe bacteria: | - Procaryotic (no nuclei or membrane bound organelles but cell structure/wall) - Larger than viruses - Contain a single strand of DNA - Classified on shape: spherical, oval, rod shaped, spiral, comma. - Multiply readily in blood by binary fusion (divide into two) |
| Provide examples of disease caused by bacteria. | - Tuberculosis - Bacterial pneumonia - Leprosy - Cholera - Tetanus |
| True or false: Bacterial colonies can be seen in liquid. | FALSE: BACTERIAL COLONIES CANNOT BE SEEN IN LIQUID. |
| What are protozoans? | Microscopic, cellular, eucaryotes. - Have nucleus + membrane bound organelles - Larger than bacteria - Reproduce by binary fission (divide into two) - Classified by movement: flagella, cilia, pseudopods or sporozoa |
| Provide examples of diseases caused by protozoans: | -Malaria - African sleeping sickness - Amoebic dysentery - Giardia - Cryptosporidiasis |
| What is fungi? | - Eucaryotic, cellular - Can be microscopic or macroscopic - Heterotrophic organism - Can be parasitic - Can be unicellular (yeast) or multicellular (mushrooms). |
| Provide examples of diseases emerging from a fungi pathogen. | - Athlete's foot - Thrush - Ringworm - Tinea |
| What are macroparasites? | - Can be seen with the naked eye - Can cause disease directly or be a vector for a disease transmission - Endoparasites (live in body: tapeworm, liver fluke) - Ectoparasites: live outside body (lice, fleas, ticks). |
| How do you name pathogens? | Genus species -Capital and lowercase respectively |
| > Syllabus point: Gather and process information to trace the historical development of our understanding of the cause and prevention of malaria | :) |
| What causes malaria? | - Five species of the protozoan: PLASMODIUM - P. falciparum, P. vivax, P. malariae, P. ovale, P. knowlesi * (P. knowlesi has a 24hr life cycle in humans → only transmitted from monkeys to humans via the female Anopheles mosquito) |
| How is malaria transferred? | - From monkeys to humans: By mosquito: female Anopheles mosquito (vector) - Intermediate host: human - Final host: female Anopheles mosquito. |
| How do Anopheles mosquitos infect humans with malaria? | - Mosquito feeds on human blood - Injects saliva containing an anticoagulant in humans. - If the saliva contains Plasmodium sporozoites = HUMAN INFECTED. |
| What do Plasmodium sporozoites do? | - Invade liver and reproduce asexually |
| What happens after 2-4 weeks? | - Merozoites of the parasite burst out with toxins - INVADE RED BLOOD CELLS. |
| What happens to the merozoites? | - Turn into gametocytes which are sucked up by mosquito. |
| In the gut of the female Anopheles mosquito.... | sexual reproduction occurs with the gametocytes. - Meiosis occurs = sporozoites - Sporozoites migrate to salivary gland - injected into human that mosquito bites. |
| When merozoites burst out, what is released and what is its effect? | Toxins are released = can cause fever (41 degrees) = headache, nausea, shivering fits, profuse sweating. |
| How often do malaria attacks occur? | Every 48 or 72 hours |
| How long can a malaria attack last? | 2+ hours |
| What happens after the attack? | The body temperature may return to normal and the host will feel better but weak. - Anaemia from loss of blood cells and haemoglobin |
| What is the most serious type of malaria? | The most serious malaria is caused by P. falciparum as the host become weak with each attack and most die if untreated. |
| What is the host response when the Plasmodium is in the red blood cells? | - Produces antibodies. |
| Why is it difficult for antibodies to counter malaria? | - Surface antigen of the cell membrane of Plasmodium changes constantly, therefore unrecognised by antibodies. |
| True of false? While in the liver, the Plasmodium is isolated from the immune system of the host. | True. |
| Which three areas have been targeted to prevent Malaria? | 1) Destruction of malaria parasite, using drugs 2) Destruction of the vector (Anopheles mosquito) using insecticides and introducing fish to eat the parasite's larvae, draining stagnant water. 3) Protection of host: preventative methods: vaccinations, drugs: prophylactics, protective clothing, insect repellant. |
| How can malaria be treated? | Anti-malarial drugs: Quinine, Chloroquine. Artemisinin |
| How can malaria be controlled? | - Draining stagnant water - Control with insecticides |
| Skipped history of Malaria | :( |
| > Syllabus point: Identify the role of antibiotics in the management of infectious disease | :) |
| What do antibiotics do? | - Kill bacteria - Manage infectious diseases caused by BACTERIA - Ineffective against viruses. - are chemicals which destroy disease causing bacteria and inhibit its growth without harming host. |
| Provide examples of antibiotics: | - penicillin -Tetracycline - cephalosporins - sulfonamides - erythromycin |
| QUICK ATTACK QUESTION: Which of the above stated antibiotics is the first discovered antibiotic? | - Pencillin |
| Explain how penicillin acts to destroy bacteria: | - Accumulate in cell of bacteria + stop them from making new walls when dividing. |
| Explain how amphotericin acts to destroy bacteria: | - destroy cell membrane |
| Explain how: Erythromycin acts to destroy bacteria: | - Interfere with protein synthesis - Bacteria can't make important compounds = death |
| > Syllabus point: Process information from secondary sources to discuss problems relating to antibiotic resistance | :) |
| How does antibiotic resistance work? | - At first: dramatic effects on disease causing pathogen - Over time, overuse = virulent bacteria = resistant = drug resistance in pathogen. |
| How does resistance evolve? | - If an antibiotic is used to kill a certain bacteria, it may not kill some bacteria which is resistant to it. Hence, the patient will feel better for a while because of the bacteria is killed, however, the infectious will grow and affect the patient again. This time though, the antibiotic cannot be used as all the bacteria which have grown, are resistant to it. |
| What are some practices which contribute to antibiotic resistance of pathogens? | 1) overuse of antibiotic for treatments: cold, fever (viruses, not bacteria). 2) Cleaning agents in house use antibiotics = result in resistant bacteria evolving = becoming common. 3) Farm animals - fed antibiotics --> we get meat which may have these = more resistant bacteria. |
| What are the issues with antibiotics? | - We now have infections which are resistant to almost all antibiotics. - E.g. Vancomycin (antibiotic) used only when all others have failed = now reducing effectiveness due to VRE (vancomycin-resistant enterococci) infections and 'golden staph' = resistance = "superbugs". |
| These resistant infections are highly serious; how can you treat them? | - Not many ways - Try experimental drugs. |
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