Topic 5 – Health, Disease and the Development of Medicines- Treating Disease Flashcards
What is an antibiotic
● A substance that kills or inhibits the growth of bacteria (no effect on viruses)
● No effect on cells in the host organism ● Produced by living organisms e.g. fungi
Describe how ‘target’ molecules for new medicines can be identified
comparisons of the genomes of unaffected individuals and those who are affected by a disease to identify potential disease-causing alleles
● The alleles themselves or the proteins that they code for can be used as a target
Outline the stages of drug development
- Screening for potential drugs 2. Preclinical trials
- Clinical trials
- Approval by a medical agency
Describe the process of screening
● Uses a machine to test large libraries of chemical substances
● Enables identification of pre-existing chemicals which may affect the target molecule
● Chemicals may be altered, allowing scientists to produce a drug that reacts with target molecules in a specific way
What do preclinical trials involve?
Drug tested on cultured human cells and using computer models to determine its toxicity (potential to cause damage) and efficiency
● Drug then tested on live animals to establish a safe dose for humans and observe any side effects
What happens during clinical screening?
The drug is first tested on healthy human volunteers to ensure that it is safe to use and has no other unwanted effects on the body
● Drug then tested on patients with the disease to determine its efficacy. Dosage is slowly increased until an upper limit is established. Optimum dosage is found.
What are placebos?
A substance that appears just like the real drug but has no effect on the recipient
What is a blind trial?
● Where the participants don’t know whether they are receiving the new drug or the placebo
● Prevents the patient’s bias affecting the results
What is a double-blind trial
● Neither the participants nor the doctors know who is receiving the new drug or the placebo
● Prevents bias from doctors when analysing the results
what is the problem associated with using placebos on patients with a disease
Is it ethical to prescribe a sick patient with a placebo knowing that it will not help their condition improve?
What are monoclonal antibodies (mAbs)?
Antibodies that are clones from one parent cell
● Specific to one type of antigen
Describe how monoclonal antibodies are produced
- Specific antigen injected into an animal
- B-lymphocytes producing complementary antibodies extracted
- B-lymphocytes fuse with myeloma cells to form hybridoma cells
- Hybridoma cells cultured
- Monoclonal antibodies collected and purified
What are myeloma cells?
Type of tumour cell
Outline the uses of monoclonal antibodies
Detection of pathogens
● Location of cancer cells and blood clots ● Treatment of cancer
● Used in pregnancy test kits
What do pregnancy kits test for?
hCG in urine
What does a pregnancy test consist of?
A stick containing monoclonal antibodies (mAbs) specific to hCG:
● mAbs attached to a blue bead (free to move)
● mAbs fixed to the test stick
Describe what happens to the test stick if a woman is pregnant
hCG in urine binds to mAbs attached to a blue bead
● mAbs with hCG diffuse up dipstick
● mAbs fixed to the stick bind to hCG
● Blue line forms
describe what happens to the test stick if a woman is not pregnant (biology only/higher)

No hCG in urine so a blue line is not formed

What is the advantage of using monoclonal antibodies to test for pathogens?
● Specific to one particular antigen ● Very accurate
● Quick results
Why can monoclonal antibodies be used to target cancer cells?
● Cancer cells have specific antigens called ‘tumour markers’ on their membranes
● mAbs are specific to one type of antigen so can be targeted to ‘tumour markers’ without damaging other cells
describe how monoclonal antibodies can be used to diagnose cancer
mAbs tagged to a radioactive substance
● mAbs injected into the patient’s bloodstream
● mAbs bind to ‘tumour markers’ on cancer cells
● Emitted radiation is detected using a specialised scanner enabling doctors to determine the location of cancer cells
How can monoclonal antibodies be used to target drugs to cancer cells?
mAbs attached to an anti-cancer drug
● mAbs injected into the patient’s bloodstream
● mAbs bind to ‘tumour markers’ on cancer cells
● Anti-cancer drug destroys cancer cells
Why are cancer treatments that use monoclonal antibodies favoured over traditional treatments?
Radiotherapy and chemotherapy target rapidly dividing cells
● Healthy cells (e.g. hair follicle cells, bone marrow cells) are damaged as a consequence, producing unpleasant side effects
● mAbs only target cancer cells, reducing damage to normal cells
How can monoclonal antibodies be used to locate blood clots?
mAbs tagged to a radioactive substance
● mAbs target and bind to specific proteins in blood clots
● Radiation emitted by mAbs is detected, enabling the location of blood clots to be identified
