B6- preventing and treating diseases Flashcards
(23 cards)
what do vaccines contain?
dead or inactive forms of a pathogen
How does a vaccination work?
-inactive form of pathogen activates an immune response and antibody production
-after an immune encounter, some b lymphocytes differentiate into memory cells which remain in body
-after second wave, immune system defeats pathogen before symptoms are exhibited
what is an antibody?
a Y-shaped protein produced by the immune system to recognize and neutralize foreign substances, such as bacteria and viruses
What is an antigen
surface protein markers
how does herd immunity work?
when majority of population is vaccinated against a pathogen, it breaks a pathogen’s chain of infection and prevents spread of disease
Can you describe the specificity of antibodies?
each antibody will have a different variable region with an antigen-binding site that matches one antigen, they are complementary to eachother
Why can’t antibiotics treat viral infections?
-viruses rely on host cells to replicate unlike bacterial cells which replicate asexually
-bacterium have a peptidoglycan cell wall which can be damaged unlike viruses which are simply genetic material coated with a protective protein
What are antibiotic resistant bacteria?
-gained resistance due to changes in their genetic material often through mutations
-can’t be damaged by antibiotics
How do antibiotic bacteria arise?
resistant bacteria outcompete non-resistant bacteria causing the resistant traits to become more common in the population
Can you name some drugs based on extracts from plants or microorganisms?
The heart drug digitalis originates from foxgloves
The painkiller aspirin originates from willow.
Penicillin was discovered by Alexander Fleming from the Penicillium mould.
What events led to the production of penicillin?
He noticed that a mould had grown on one of his petri dishes and that the bacteria around the mould had been killed. He identified the mould as Penicillium notatum, which was later found to produce a substance that could kill bacteria, which Flemming called Penicillin
How are antibiotics tested for efficacy?
The drugs are tested using computer models and skin cells grown using human stem cells in the laboratory. This allows the efficacy and possible side effects to be tested. Many substances fail this first test of a preclinical drug trial because they damage cells or do not seem to work.
How do you trial a new drug?
The drugs are tested using computer models and skin cells grown using human stem cells in the laboratory.
Drugs that pass the first stage are tested on animals in the second part of a preclinical drug trial.
Drugs that have passed animal tests are used in human clinical trials.
What is a placebo?
A placebo is a ‘dummy’ treatment with no medical or therapeutic value. A placebo looks like the drug being tested but only contains sugar.
How do human clinical trials work?
Clinical trials use healthy volunteers and patients. Very low doses of the drug are given at the start of the clinical trial. If the drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug.
Why are placebos used in a clinical trial?
A placebo is used in clinical trials to compare the results of the experimental drug with a control group. By comparing the results of the two groups, scientists can determine if the experimental drug is having a real effect on the participants.
What is a double blind trial?
A double-blind trial is a type of clinical trial where neither the participants nor the researchers know which group is receiving the experimental drug and which is receiving the placebo. This helps to reduce any biases that may influence the results of the trial.
What is a monoclonal antibody?
Monoclonal antibodies are produced from a single clone of cells. The antibodies are specific to one binding site on one protein antigen and so are able to target a specific chemical or specific cells in the body.
What is the procedure for making monoclonal antibodies?
-inject pathogen into a mouse
-stimulates the production of mouse lymphocytes to make a particular antibody
-lymphocytes are combined with a tumour cell to make a hybridoma
-the hybridoma can both divide and produce the specific antibodies
-Single hybridoma cells are cloned to produce many identical cells that all produce the same antibody
-A large amount of the antibody can be collected and purified.
How do pregnancy tests work (if you’re not pregant)
-person gives a urine sample (if they are pregnant, it will contain hCG)
-they urinate on the closest part of test strip- here, there are blue beads with monoclonal antibodies specific to hCG attached
-the urine will wash these beads (they aren’t fixed) to the end of the strip where there are fixed monoclonal antibodies and nothing will happen so test strip doesn’t go blue
How does a pregnancy test work if you are pregnant?
-urinate on test strip
-urine will contain hCG which binds to antibodies on blue beads
-as urine flushes these beads along the test strip, the hCG they’re carrying binds to fixed antibodies as well
-blue beads are held in place
-entire strip appears blue (indicates positive test result)
why do some tests have two lines?
to use as a control method
What are some other uses of monoclonal antibodies?
In laboratories to measure the levels of hormones and other chemicals in blood, or to detect pathogens.
In research to locate or identify specific molecules in a cell or tissue by binding to them with a fluorescent dye.
To treat some diseases: for cancer the monoclonal antibody can be bound to a radioactive substance, a toxic drug or a chemical which stops cells growing and dividing. It delivers the substance to the cancer cells without harming other cells in the body.
