B6 Preventing And Treating Disease

Question 1

What is vaccination?

Answer 1

Injecting a dead/inactive form of a pathogen into the body

Question 2

Why don’t vaccinations cause disease in the patient?

Answer 2

Because the pathogen is dead/inactive

Question 3

Explain how vaccinations prevent illnesses

Answer 3

First, a dead/inactive form of the pathogen is injected into the patient, the patient’s white blood cells are now stimulated to make antibodies against the pathogen. At the same time, the white blood cell divides by mitosis, producing many copies of itself that can remain in the blood for decades. If the same pathogen invades the body again the white blood cells can quickly produce the correct antibodies to destroy the pathogens, preventing infection.

Question 4

What is herd immunity?

Answer 4

When there is a high enough percentage of vaccinated people so that there is an extremely low likelihood of an unvaccinated person contracting the disease, as nobody around them can pass the pathogen on.

Question 5

What is antibiotic resistance?

Answer 5

Certain antibiotics becoming ineffective against certain bacteria as they had been overused, so the bacteria had evolved and no longer became killed by the antibiotic.

Question 6

How are doctors careful when prescribing antibiotics?

Answer 6

They use specific antibiotics for specific diseases

Question 7

Why won’t doctors prescribe antibiotics for conditions caused by viruses?

Answer 7

Antibiotics don’t kill viruses

Question 8

Give one advantage and one disadvantage of painkillers

Answer 8

• They help relieve pain (treat the symptoms)
• They don’t kill pathogens (don’t treat the disease
  itself)

Question 9

Why is it difficult to develop drugs that kill viruses?

Answer 9

Viruses invade human cells, so it’s hard to develop drugs that don’t harm the body’s tissues

Question 10

Which plant was used to extract the heart drug Digitalis?

Answer 10

Foxgloves

Question 11

Which drug was extracted from the foxglove plant?

Answer 11

Digitalis

Question 12

Which plant was used to extract the painkiller aspirin?

Answer 12

The willow tree

Question 13

Which drug was extracted from the willow tree?

Answer 13

Aspirin

Question 14

Which microorganism was used to extract penicillin?

Answer 14

The mould penicillium

Question 15

What is the first stage of drug testing?

Answer 15

Pre-clinical testing

Question 16

What happens during pre-clinical testing?

Answer 16

Tests are carried out on cells, tissues or on live animals (e.g. rats) to determine the toxicity of the drug and whether it would be safe for humans

Question 17

What is the second stage of drug testing?

Answer 17

Clinical testing

Question 18

What happens during clinical testing?

Answer 18

Low doses of the drug are given to healthy volunteers to see if the drug is safe in humans. If the drug is safe then clinical testing continues to find the optimum dose.

Question 19

What is an optimum dose?

Answer 19

The best dose to treat a disease with the least side effects

Question 20

What is a placebo?

Answer 20

A tablet/drug with no active ingredient

Question 21

What is a double-blind trial?

Answer 21

A trial in which the doctor nor patient knows whether their drug is a placebo or not

Question 22

What is the benefit of a double blind trial?

Answer 22

It prevents bias

Question 23

Which white blood cells produce antibodies?

Answer 23

Lymphocytes

Question 24

What is another name for foreign objects in the body?

Answer 24

Antigens

Question 25

Describe how monoclonal antibodies are produced

Answer 25

First, inject an antigen into an animal (e.g. a mouse), the mouse's WBCs will produce antibodies against the antigen. These antibodies can be extracted, however they will not divide by mitosis, so they are fused with a tumour cell, which is very good at dividing by mitosis, the fused cell is called a Hybridoma. Hybridoma cells can produce antibodies and divide by mitosis, next, a single Hybridoma cell which produces the desired antibody is chosen, and allowed to divide to form a clone of identical Hybridoma cells, so the antibodies produced are al identical - these are monoclonal antibodies as they all come from a single Hybridoma clone. These antibodies can then be collected and purified.

Question 26

What is a Hybridoma cell?

Answer 26

A lymphocyte and tumour cell fused together

Question 27

What are the benefits of monoclonal antibodies?

Answer 27

They are specific to one binding site on one protein antigen, and can target a specific chemical/cells in the body.

Question 28

How are monoclonal antibodies used in pregnancy testing?

Answer 28

They're used to detect a specific hormone released by the placenta of the developing fetus

Question 29

How are monoclonal antibodies used in lab testing?`

Answer 29

They can be used to measure the levels of hormones in the blood. e.g. if a person is tired they can take a blood test and see if they have a low level of a certain hormones

Question 30

How are monoclonal antibodies used for location?

Answer 30

They can be attached to fluorescent dyes, and antibodies can stick to specific molecules in the cell, allowing their locations to be seen

Question 31

How are monoclonal antibodies used to treat diseases?

Answer 31

Scientists can make monoclonal antibodies specific to cancer cells, a radioactive substance is then attached to the antibody, which attaches to the cancer cells when injected into the blood, stopping them from dividing without harming body tissues

Question 32

What is a disadvantage of using monoclonal antibodies?

Answer 32

They have more side effects than initially expected, and some are very harmful.

Question 33

A large proportion of a population is vaccinated against a particular pathogen. Suggest why the spread of the pathogen will be very much reduced (2)

Answer 33

- A larger proportion of the population that have been vaccinated won't catch the disease, which means that most people who aren't vaccinated would be less likely to catch the disease are there are less people to pass it on.

Question 34

What is a monoclonal antibody?

Answer 34

An antibody produced from a single hybridoma cell that is specific to a certain antigen

Question 35

Suggest two reasons why a traveller might get vaccinated against a specific disease before travelling to a country that had recently had an outbreak of said disease (2)

Answer 35

- To reduce the risk of the traveller contracting the disease - To reduce the risk of the traveller spreading the disease after returning to their home country

Question 36

What are some uses of monoclonal antibodies?

Answer 36

• for diagnosis such as in pregnancy tests • 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. ( • identify / locate specific molecules / other hormones • locate blood clots • diagnose / treat some cancers )

Question 37

Outline the principle of how both enzymes and antibodies work

Answer 37

Through the principle of specificity / molecules fitting together Each antibody binds to one specific antigen Each enzyme catalyses the reaction of (one) specific substrate(s) / a substrate that is complementary to the enzyme's active site;