B6 Flashcards
How do vaccines work?
Involve injecting small amounts of dead or inactive pathogen. These carry antigens which cause your body to produce antibodies to attack them - even though the pathogen is harmless. But if live pathogens of the same type appear after that, the white blood cells can rapidly mass-produce antibodies to kill off the pathogen.
What are the pros of vaccines?
They have helped control lots of communicable diseases that were once common in the UK.
Big outbreaks of diseases - called epidemics - can be prevented if a large percentage of the population is vaccinated. That way even the people who aren’t vaccinated are unlikely to catch the disease because there are fewer people able to pass it on.
What are the cons of vaccines?
They don’t always work
You can have a bad reaction (swelling, fever, seizure)
What are painkillers and antibiotics?
Painkillers: drugs that relieve pain, but don’t actually tackle the cause of the disease or kill pathogens.
Antibiotics: they kill the bacteria causing the problem without killing your own body cells.
How can viruses be killed?
They can’t be, using antibiotics because they reproduce using your body cells, which makes it very difficult to develop drugs that destroy just the virus without killing the body’s cells.
How do bacteria become resistant to antibiotics?
Some of the bacteria might be resistant to antibiotics.
When you treat the infection, only the non-resistant strains of bacteria will be killed.
The individual resistant bacteria will survive and reproduce, and the population of the resistant strain will increase.
To slow down the rate of development of resistant strains, it’s important for doctors to avoid over prescribing antibiotics. It’s also important that you finish the whole course of antibiotics and don’t just stop once you feel better.
What are some examples of drugs that come from plants?
Aspirin is used as a painkiller and to lower fever. It was developed from a chemical found in willow.
Digitalis is used to treat heart conditions. It was developed from a chemical found in foxgloves.
What is the story of Alexander Flemming?
Alexander Fleming was clearing out some Petri dishes containing bacteria. He noticed that one of the dishes of bacteria also had mould on it and the area around the mould was free of the bacteria.
He found that the mould (called Penicillium notatum) on the Petri dish was producing a substance that killed the bacteria — this substance was penicillin.
How is drug testing done?
- (Preclinical testing) The drug is tested on human cells and tissues in the lab.
- (Preclinical testing) Test the drug on live animals (to test for efficacy, toxicity and to find the best dosage).
- Tested on healthy volunteers (to test for side effects). A very low dose is given and then this is gradually increased.
- The drug is tested on people suffering from the illness (to find the optimum dose). Patients are randomly put into two groups. One is given the new drug, the other is given a placebo. This is so the doctor can see the actual difference the drug makes, without any subconscious bias. The trials are blind - the patient’s don’t know what drug they are getting. They are often double-blind - neither the doctor of the patient know until the results have been gathered.
- The results are peer reviewed to prevent false claims.
- The results are published.
How are monoclonal antibodies produced?
- Mouse injected with chosen pathogen. The mouses immune system responds.
- B-lymphocytes produce antibodies.
- A fast-dividing tumour cell from a lab. They can’t make antibodies.
- B-lymphocyte fused with tumour cell
- This makes a hybridoma which can make specific antibodies. They are screened to make sure they are producing the correct one.
- It divides quickly to produce lots of clones that produce the monoclonal antibodies.
- They are called Monoclonal antibodies (because they came from a single cloned cell).
- Antibodies are harvested and used for a range of purposes.
How do monoclonal antibodies work in pregnancy tests?
- The bit of stick you wee on has some antibodies to the hormone (HCG - found in the urine of women only when they are pregnant), with blue beads attached.
- The test strip has some more antibodies to the hormone stuck onto it (so they can’t move).
- If you’re pregnant the hormone binds to the antibodies on the blue beads. The urine moves up the stick, carrying the hormone and the beads. The beads and hormone bind to the antibodies on the strip. So the blue beads get stuck on the strip, turning it blue.
- If you’re not pregnant and you wee on the stuck, the urine still moves up the stick, carrying the blue beads. But there’s nothing to stick the blue beads onto the test strip, so it doesn’t go blue.
How can monoclonal antibodies be used to treat cancer?
Cancer cell antigens are called tumour markers, found on their cell membranes.
In the lab, a monoclonal antibody can be made to bind to these tumour markers.
An anti-cancer drug can be attached to these monoclonal antibodies. (Radioactive substance, toxic drug, or chemical which stops cancer cells growing and dividing).
The antibodies are given to the patient through a drip.
The antibodies target the cancer cells.
The drug kills the cancer cells but doesn’t kill any normal body cells near the tumour.
What are some other uses of monoclonal antibodies?
Bind to hormones and other chemicals in blood to measure their levels.
Test blood samples in laboratories for certain pathogens.
Locate specific molecules on a cell or in a tissue:
First monoclonal antibodies are made that will bind to the specific molecules you’re looking for.
The antibodies are then bound to a fluorescent dye.
If the molecules are present in the sample you’re analysing, the monoclonal antibodies will attach to them, and they can be detected using the dye.
What are the pros and cons of monoclonal antibodies?
Pros:
Less side effects than for standard chemotherapy or radiotherapy.
Cons:
They do cause more side effects than they thought they would. Fever, vomiting and low blood pressure. This means that they are not as widely used as treatments as scientists had originally thought they might be.
