Treating disease Flashcards
What is an antibiotic?
● Asubstance 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 targe
Outline the stages of drug development
- Screening for potential drugs
- 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 testing?
● 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?
Astick 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
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
