Chapter 6 Preventing and Treating Diseases

Question 1

What is a vaccine?

Answer 1

A vaccine is a dead microbe or part of a microbe that teaches your body how to fight a live one.

Question 2

What does MMR vaccinate against?

Answer 2

Measles, mumps and rubella

Question 3

How does vaccination stop you from getting sick?

Answer 3

Vaccinations give people immunity to disease.

Question 4

What are 2 types of immunity?

Answer 4

Natural and artificial immunity.

Question 5

What type of immunity does vaccination give you?

Answer 5

Artificial immunity.

Question 6

What is an antigen?

Answer 6

Cells have proteins and other substances on their surfaces that are only found on those types of cells. These are called antigens.

Question 7

How do lymphocytes (white blood cells) use antigens?

Answer 7

Lymphocytes are able to recognise cells as ‘self’ or ‘non-self’. Pathogens like bacteria, viruses and fungi have antigens on their surfaces recognised as ‘non-self’ by lymphocytes.

Question 8

What happens once a lymphocyte recognises an antigen on a pathogen?

Answer 8

It begins to produce antibodies which have a shape that is complementary to the antigen and allow them to bind to it.

Question 9

What is herd immunity?

Answer 9

Herd immunity is when unvaccinated members of a population are prevented from infection through having a large proportion of the population vaccinated.

Question 10

What do painkillers do?

Answer 10

Painkillers treat the symptoms of disease but they do not kill the pathogens that cause the disease.

Question 11

What do antibiotics do?

Answer 11

Antibiotics kill bacterial pathogens that cause illness.

Question 12

Give some examples of antibiotics.

Answer 12

Penicillin, tetracycline.

Question 13

Why do doctors prescribe different antibiotics depending on the bacteria you are infected with?

Answer 13

Specific bacteria need to be treated with specific antibiotics because different antibiotics might not work.

Question 14

How can doctor’s be sure the antibiotic prescribed will work on the infection you have?

Answer 14

Doctor’s can take a swap to sample the bacteria and then culture it on a plate. They can then use different antibiotics on the culture to see which is the most effective.

Question 15

How do antibiotics kill bacteria?

Answer 15

Antibiotics stop cellular processes that happen in bacteria but not animal cells. This way the bacterial cells die but your own cells are unharmed. One way they work is by targeting bacterial cell walls.

Question 16

How do bacteria become resistant to antibiotics?

Answer 16

Overuse of antibiotics allows bacteria to evolve resistance.

Question 17

Can antibiotics be used to treat viral infections like influenza or the common cold?

Answer 17

No, antibiotics can only be used to treat bacterial infections.

Question 18

Why are antibiotics ineffective on viruses?

Answer 18

Viruses live inside cells and antibodies work on the surface of pathogens.

Question 19

What are antiviral medications?

Answer 19

Antiviral medications can help treat viral infections.

Question 20

Why are there very few antiviral medications used?

Answer 20

It is very difficult to develop drugs to treat viruses without also damaging the body’s tissues.

Question 21

What was the source of most traditional drugs?

Answer 21

Plants

Question 22

What is digitalis used for and where does it come from?

Answer 22

Digitalis is used to treat heart conditions and it comes from Foxgloves.

Question 23

What is aspirin used for and where does it come from?

Answer 23

Aspirin is used as a painkiller and it comes from Willow trees.

Question 24

What is penicillin used for and where does it come from?

Answer 24

Penicillin is used as an antibiotic and it comes from the mould Penicillium.

Question 25

Who discovered penicillin?

Answer 25

Alexander Fleming.

Question 26

What 3 things are new drugs tested for?

Answer 26

Toxicity, efficacy and dose.

Question 27

What does toxicity mean?

Answer 27

Toxicity is how poisonous or harmful a substance is.

Question 28

What are side effects?

Answer 28

Side effects are unintended unpleasant effects such as nausea, headache, bleeding or heart damage.

Question 29

What does efficacy mean?

Answer 29

Efficacy is how well a drug is at treating the condition it is meant to treat.

Question 30

What are the 3 stages in pre-clinical trials?

Answer 30

Testing on: 1. Cells 2. Tissues 3. Live animals

Question 31

What are the stages in clinical trials?

Answer 31

1. Testing on healthy volunteers Very low doses are given to healthy volunteers If the drug is found to be safe then trials continue to determine safe doses. 2. Testing on patients Some patients are given the drug and others are given a placebo in a double blind trial.

Question 32

What is a placebo?

Answer 32

A placebo is a tablet or something like the real treatment but without the actual medicine.

Question 33

What is a double blind trial?

Answer 33

This is when neither the researcher nor the patient knows whether they have been given the drug or the placebo. It is done to reduce bias.

Question 34

Why are the results of drug testing trials studied in detail by other scientists?

Answer 34

To avoid bias and to make sure the claims are true. It also stops the drug companies from making any false claims.

Question 35

What is a monoclonal antibody? (TRIPLE ONLY)

Answer 35

A monoclonal antibody is an antibody produced from cloned cells. They are specific to proteins on the surface of the pathogen it was produced to fight against.

Question 36

How does a monoclonal antibody work? (TRIPLE ONLY)

Answer 36

1. The monoclonal antibody is specific to an antigen (protein on the surface of a pathogen) 2. The monoclonal antibody attaches to the surface of the pathogen. 3. This stops the pathogen from binding to the human cells. 4. Lymphocytes neutralise the pathogen.

Question 37

Give 4 uses for monoclonal antibodies. (TRIPLE ONLY)

Answer 37

1. For diagnosis as in pregnancy tests. 2. In laboratories to measure the levels of hormones and other chemicals in the blood (like in drug tests) or to detect pathogens. 3. In research to locate or identify specific molecules in a cell or tissue by binding them with a fluorescent dye. 4. To treat some diseases such as cancer. The monoclonal antibody can be bound to a radioactive substance or a drug. It can then deliver the radiation or drug to the cancer cells without harming healthy cells.

Question 38

Describe how a pregnancy test works. (TRIPLE ONLY)

Answer 38

1. As urine passes through reaction zone hCG hormone binds to the mobile hCG antibody (in the reaction zone). 2. The mixture passes up the stick and hCG hormone binds to the immobilised hCG antibodies in the results zone. 3. The other antibodies which do not attach to HCG bind to antibodies in the control zone. 4. A blue dye appears in both control and results zones to show a positive result.

Question 39

Why are monoclonal antibodies not used more widely? (TRIPLE ONLY)

Answer 39

Monoclonal antibodies create side effects.

Question 40

Describe the stages in the production of monoclonal antibodies. (TRIPLE ONLY)

Answer 40

1. Inject the mouse with the virus (or pathogen) you would like antibodies against. 2. This stimulates the mouse to make lymphocytes to produce the antibody. 3. The mouse lymphocytes are fused with tumour cells to produce hybridoma cells. 4. The hybridoma cells are cloned and they divide rapidly. 5. The hybridoma cells produce antibodies that are specific to the virus (or pathogen). 6. The antibodies are extracted and purified.