Topic 3 - Infection and response Flashcards
What is a pathogen and what are the four types? Also how can they be spread?
Pathogen:
— A pathogen is a microorganism that can cause infectious diseases. A pathogen can either be bacteria, viruses, fungi or protists.
— They are either spread by water, air, direct contact or vectors.
Compare bacteria and viruses.
Both bacteria and viruses reproduce rapidly inside the body. The difference is that bacteria is found outside the cell and produce toxins that damage tissues which make us feel ill. Viruses live and reproduce inside cells which causes cell damage.
What are three viral diseases? Explain all in detail.
Measles:
— A disease that shows symptoms of a fever and red skin rash. Spread by droplets from an infected person’s cough or sneeze. Can be fatal if complications arise hence the reason young children are vaccinated from a young age.
HIV:
— A flu-like illness. Spread by sexual contact or exchanging bodily fluids by sharing needles.
Tobacco mosaic virus:
— TMV affects plants and causes discolouration of plants therefore photosynethesis cannot take place which affects growth.
Give an example of a fungal and protist disease.
Rose black spot:
— This is a fungal disease which causes the growth of purple or black spots which limits the amount of photosynthesis that can take place. This affects growth. Spread by water or wind, prevented using fungicides or removing the affected leaves.
Malaria:
— This is a protist disease with a life cycle that includes mosquitoes. Causes repeating episodes of fever and can be fatal. Prevented using insecticides or mosquito nets.
Explain two bacterial diseases in detail.
Salmonella:
— Food poisoning caused by the injestion of food or food preapared in unhygenic conditions. Symptoms are fever, stomach cramps, vomting, diarrhoea. Poultry is often vaccinated against salmonella to reduce the spread.
Gonorrhoea:
— A sexually transmitted disease. Symptoms are pain when urinating and thick yellow or green discharge. Can be prevented using barrier contraception methods. Used to be treated with antibiotic penicillin but many strains became resistant to it.
What are four ways to reduce the spread of diseases?
- – Destroying vectors
- – Vaccinations
- – Being hygienic
- – Isolating infected individuals
Explain how different parts of the human defence system prevent diseases.
Skin:
— Acts as barrier and secretes antimicrobial substances.
Nose:
— Contains hairs and mucus which trap pathogens
Trachea and bronchi:
— Secretes mucus to trap pathogens. Lined with cilia to waft away pathogens.
Stomach:
— Hydrochloric acid to destroy pathogens
What are three ways white blood cells defend against pathogens?
Phagocytosis:
— White blood cells engulf and digest the pathogens
Producing antibodies:
— Pathogens contain antigens on its surface. White blood cells recognise this as foreign and begin producing proteins called antibodies to lock into the antigens. The antibodies are rapidly reproduced and remembered for next time incase the person is infected again.
Producing antitoxins:
— Bacteria produces toxins so the antitoxins counteract the invading bacteria.
How do vaccinations help with fighting diseases?
Vaccinations involve injecting a person with dead or inactive pathogens which stimulate the white blood cells to produces antibodies to counteract the antigens. This is done so that if a person is infected by the same pathogen, the memory cells allow the white blood cells to rapidly produce the correct antibodies and prevent the infection
What is used to kill bacteria and why can’t it be used to kill viruses? Also why can you not use painkillers to cure bacterial diseases?
Antibiotics are used to kill bacteria however cannot be used to kill viruses because viruses live inside the cells whereas bacteria does not. Therefore antiretroviral drugs are used to cure viral infections. But it is very hard to cure viral diseases without damaging the body cells. You also cannot use painkillers to cure bacteria because painkillers only help to cure the symptoms of the disease.
Why might antibiotics not always work to kill all the bacteria?
Bacteria can mutate rapidly. The mutations can cause the bacteria to produce resistant strains therefore only the non-resistant strains of bacteria will be killed.
What are the three drugs that originally came from plants or microorganisms?
- – Aspirin came from a chemical found in willow.
- – The heart drug digitalis came from a chemical found in foxglove.
- – Alexander Fleming discovered penicillin from the Penicillium mould.
What are the three main stages in drug testing? Explain each.
Step 1:
— Preclinical testing on human cells and tissues
Step 2:
— Preclinical testing on live animals. This is to test for efficacy and toxicity.
Step 3:
— Clinical trials using healthy volunteers and patients. First tested on healthy volunteers to look for side effects, they are given a low dosage and its gradually increased to find optimum dosage. Then it is tested on actual patients suffering from the disease. They are put into two groups and one group is given a placebo, the other is given the actual drug. Often these are double blind trials where neither the doctor or patients know who have the placebo to prevent doctors being influced by their prior knowledge.
How are monoclonal antibodies produced?
A mouse is injected with a chosen antigen. Then B lymphocytes from the mouse are taken and fused with tumor cells to produce hybridoma cells. Hybridoma cells divide rapidly and are then collected and purified to produce the monoclonal antibodies.
What are some uses of monoclonal antibodies? Explain each as much as you can
Pregnancy tests:
— The bit of the stick you wee on has antibodies with blue beads attached to it. The test strip has some more antibodies. If you’re pregnant, the hormone HCG binds to the antibodies and the urine moves up the stick so the beads and hormones bind to the antibodies on the test strip. If you’re not pregnant, urine still moves up but theres nothing to bind the blue beads onto the antibodies on the test strip.
Labatories and reasearch to find specific substances:
— Monoclonal antibodies can bind to hormones and other chemicals in blood to measure their levels. It can be used to test blood samples for pathogens. Or locate specific molecules by producing monoclonal antibodies that bind to the substance then the antibodies bind to fluorescent dye and if present, they will show up using the dye.
Treat diseases like cancer:
— Monoclonal antibodies are produced in a lab to bind to the tumor markers then an anti-cancer drug such as a radioactive substance, toxic drug or chemical stops cells from dividing. The antibodies are given to the patient and target the cancer cells so it kills the cancer cells but not normal body cells.
