Development of Medicines Flashcards

All 42 cards in this deck

What is an antibiotic?

A medicine that kills bacteria or stops them reproducing inside the body.

Name a bacterial cell process that antibiotics can inhibit.

Cell wall formation (e.g. penicillin), or bacterial protein synthesis, or bacterial DNA replication.

True or false? Antibiotics can be used to treat viral infections such as flu.

False. Viruses reproduce inside host cells and do not have the cell processes antibiotics inhibit, so antibiotics have no effect on them.

The antibiotic myxopyronin inhibits bacterial RNA polymerase. Why is it effective against bacteria but safe in humans?

Bacteria cannot carry out transcription, so no mRNA and no proteins are made and the bacteria die; human RNA polymerase is not affected.

What is aseptic technique?

A set of precautions used when culturing microorganisms to stop unwanted microorganisms contaminating the culture (and to stop microbes escaping).

What is an autoclave used for when culturing microorganisms?

Sterilising growth medium and petri dishes with steam at high temperature and pressure, killing any unwanted microorganisms.

Why is an inoculating loop passed through a Bunsen flame before transferring microorganisms?

To sterilise it, killing any microorganisms on it so the culture is not contaminated.

Why is inoculation carried out close to a lit Bunsen burner?

The hot air rises and carries airborne microorganisms upwards, away from the plate, reducing contamination.

Why must petri dishes and culture vials be kept covered?

To stop microorganisms from the air contaminating the culture, and to stop the cultured microorganisms escaping.

True or false? A petri dish should be sealed all the way round the lid with tape.

False. Tape it in a few places only, so oxygen can enter and harmful anaerobic bacteria are not encouraged to grow.

What are the steps to investigate the effect of different antibiotics on a bacterial culture?

e.g. testing three antibiotics on one species of bacteria

1. Spread the bacteria evenly over sterile agar using a sterile spreader.
2. Place a paper disc soaked in each antibiotic on the agar, plus a control disc soaked in sterile water; tape the lid and incubate at 25 °C.
3. Measure the diameter of the clear zone of inhibition around each disc.

What is a zone of inhibition?

The clear area of agar around a disc where the bacteria have not grown.

True or false? A larger zone of inhibition means the antimicrobial substance is less effective.

False. A larger clear zone means more bacteria were killed or prevented from growing, so the substance is more effective.

Name three variables that must be controlled when comparing antiseptics or antibiotics on agar plates.

Same species and concentration of bacteria, same size of disc and volume of substance, same incubation temperature and time (and same agar).

What are the steps to calculate the cross-sectional area of a clear zone of inhibition?

e.g. a clear zone of diameter 10 mm

1. Halve the diameter to get the radius: $r = 5$ mm.
2. Use $A = \pi r^2$: $\pi \times 5^2$.
3. Give the answer with squared units: $78.5$ mm$^2$.

Why should the antimicrobial investigation be repeated and a mean zone size calculated?

Repeats make the results more reliable and let anomalous results be spotted and excluded from the mean.

What are the four main stages in developing a new medicine?

Discovery, development, preclinical testing, clinical testing.

What happens during preclinical testing of a new medicine?

The drug is tested on cultured cells and tissues, then on animals, to check toxicity, efficacy and a suitable dose.

What happens during clinical testing of a new medicine?

It is tested on healthy volunteers at low doses to check safety, then on patients to find the optimum dose and check it works.

What is a placebo in a drug trial?

A treatment with no active drug in it, given to a control group so the drug's effect can be compared with it.

What is a double-blind trial?

A trial in which neither the patient nor the doctor knows who is getting the drug and who is getting the placebo, which prevents bias.

True or false? A new medicine is first tested on human patients with the disease.

False. It is first tested on cultured cells and animals (preclinical), then on healthy volunteers, before patients.

What is a monoclonal antibody?

An identical antibody produced from a single clone of cells, which binds to only one specific antigen.

What are the steps in producing monoclonal antibodies?

e.g. antibodies against a cancer cell antigen

1. Inject a mouse with the antigen so its lymphocytes make the desired antibody (but lymphocytes do not divide).
2. Fuse a lymphocyte with a tumour cell to make a hybridoma cell.
3. The hybridoma divides rapidly, producing large amounts of the antibody, which is collected and purified.

What is a hybridoma cell?

A cell made by fusing a lymphocyte with a tumour cell; it produces the desired antibody and also divides rapidly.

What do the monoclonal antibodies in a pregnancy test bind to?

The hormone HCG, found in the urine of a pregnant woman; a second set of immobilised antibodies traps the complex, giving a coloured line.

How are monoclonal antibodies used to locate blood clots or cancer cells in the body?

Antibodies specific to antigens on the clot or cancer cell are bound to a radioactive or fluorescent marker, injected, and detected by a scanner where they bind.

True or false? Monoclonal antibody treatment for cancer damages healthy cells as much as radiotherapy does.

False. Monoclonal antibodies bind only to antigens on the cancer cells, so healthy cells are largely unharmed and there are fewer side effects.

What is a non-communicable disease?

A disease that cannot be passed from person to person, caused by the interaction of several factors such as genes, lifestyle and environment.

What is the equation for BMI?

$\text{BMI} = \dfrac{\text{mass (kg)}}{(\text{height (m)})^2}$ — a BMI of 30 or more is classed as obese.

How do diet and exercise lead to obesity?

If energy taken in as food is greater than energy used in respiration/exercise, the excess is stored as fat and body mass increases.

How does drinking too much alcohol affect the liver?

The liver breaks down alcohol, and the toxic products damage liver cells, causing scar tissue (cirrhosis) and liver disease.

True or false? A strong correlation between a lifestyle factor and a disease proves that the factor causes the disease.

False. Correlation only shows a link; other factors may be responsible, so further evidence is needed to show cause.

What is cardiovascular disease?

Disease of the heart and blood vessels, usually caused by fatty deposits narrowing the coronary arteries.

How does smoking increase the risk of cardiovascular disease?

Nicotine raises heart rate and blood pressure, carbon monoxide reduces the oxygen the blood carries, and chemicals damage artery linings so fatty deposits build up.

What do statins do?

Lower the level of cholesterol in the blood, slowing the build-up of fatty deposits in arteries; they must be taken for life and can cause side effects.

What is a stent?

A mesh tube inserted into a narrowed artery to hold it open so blood can flow freely.

True or false? Fitting a stent cures the underlying cause of cardiovascular disease.

False. It widens the artery but does not stop further fatty deposits forming, and surgery carries risks of infection and blood clots.

Give the advantage and the disadvantage of using lifestyle changes to treat cardiovascular disease.

Advantage: cheap with no side effects or surgical risk. Disadvantage: they rely on the patient sticking to them and work slowly.

True or false? Most non-communicable diseases are caused by several risk factors interacting, rather than by one single cause.

True. e.g. cardiovascular disease risk depends on diet, exercise, smoking and inherited factors together.

What are the steps to calculate and interpret a waist : hip ratio?

e.g. a woman with a waist of 80 cm and hips of 100 cm

1. Measure waist and hip circumference in the same units: waist $= 80$ cm, hips $= 100$ cm
2. Divide waist by hip: $80 \div 100 = 0.8$
3. Compare with the table of values: $0.8$ is below $0.85$, so this is a healthy ratio for a woman (low risk of obesity-related disease).

What does a high waist : hip ratio indicate?

A lot of fat stored around the abdomen, which means a higher risk of obesity-related diseases such as cardiovascular disease and type 2 diabetes.