3. Infection and Response (drugs, developing drugs, monoclonal antibodies, plant diseases and defences)

Question 1

What are painkillers?

Answer 1

Drugs that relieve pain without actually tackling the cause of the disease or killing pathogens, they just help to reduce the symptoms

Question 2

What do antibiotics do?

Answer 2

They kill (or prevent the growth of) the bacteria causing the problem without killing your own body cells

Question 3

What do different types of antibiotics do?

Answer 3

They kill different types of bacteria, so it is important to be treated with the right one

Question 4

Do antibiotics kill viruses and why?

Answer 4

• No
• Viruses reproduce using your own body cells which makes it very difficult to develop drugs that destroy just the virus without killing the body’s cells

Question 5

How does antibiotic resistance work?

Answer 5

1. Bacteria can mutate - sometimes the mutations cause them to be resistant to an antibiotic
2. if you have an infection, some of the bacteria might be resistant to antibiotics
3. This means that when you treat the infection, only the non-resistant bacteria will be killed
4. The individual resistant bacteria will survice and reproduce, and the populatiuon of the resistant strain will increase
5. This resistant strain could cause a serious infection that can’t be treated by antibiotics

Question 6

How is the rate of development of antibiotic resistant strains slowed down?

Answer 6

• Doctors avoid over-prescribing antibiotics, so you won’t get them for a sore throat, only for something more serious
• It is also important that you finish the whole course of antibiotics and don’t just skip once you feel better

Question 7

What do plants produce to defend themselves against pests and pathogens?

Answer 7

A variety of chemicals

Question 8

What is aspirin used as and where was it developed from?

Answer 8

• It is used as a painkiller and to lower fever
• It was developed from willow trees

Question 9

What is digitallis used to treat and where was it developed from?

Answer 9

• Used to treat heart conditions
• It was developed from a chemical found in foxgloves

Question 10

How did Alexander Flemming discover Penicillin?

Answer 10

• Fleming was clearing out some petri dishes containing bacteria
• He noticed that one of the dishes of bacteria also had mould on it and the area around the mould was free of the bacteria
• He found out that the mould (penicillium notatum) on the Petri dish was producing a substance that killed the bacteria - this substance was called penicillin

Question 11

What are the
stages of preclinical testing?

Answer 11

1). Drugs are tested on human cells and tissues in the lab
2). Then the drugs are tested on live animals. This is to test efficacy, to find out about its toxicity and to find the best dosage

Question 12

What does the law in Britain suggest about drug testing?

Answer 12

Any new drug must be tested on two different live animals

Question 13

What happens in the clinical trial?

Answer 13

• First the drug is tested on healthy volunteers, this is to make sure that it doesn’t have any harmful side effects when the body is working normally
• If the testing on healthy individuals go well, the drug can be tested on people sufferring from illness
• The optimum dosage should be tested for
• To test how well the drug works, patients are randomly put into two groups. One is given the new drug
  -the other is given a placebo.
• Clinical trials are blind - the patient in this study does not know whether they’re getting the drug or the placebo

Question 14

When are the result of drug testing published?

Answer 14

After they’ve been through peer review

Question 15

What are antibodies produced by?

Answer 15

Lymphocytes

Question 16

What are lymphocytes?

Answer 16

A type of white blood cell

Question 17

Why are all the antibodies produced by monoclonal antibodies identical and all target one specific antigen?

Answer 17

Because they are produced from lots of clones of a single white blood cell

Question 18

Why are tumour cells and lymphocytes fused together?

Answer 18

• Tumour cells divide lots so they can be grown very easily
• Lymphocytes produce antibodies
• So by fusing them together you get a hybridoma cell, which can be cloned to get lots of identical cells
• These cells produce the same antibodies which can be collected and purified

Question 19

Why are monoclonal antibodies really useful?

Answer 19

Because they will only bind to one type of antigen, meaning that you can use them to target a specific cell or chemical in the body

Question 20

How are monoclonal antibodies used in pregnancy tests?

Answer 20

• A hormone called HCG is found in the urine of women only when they are pregnant, which pregnancy sticks detect
• The bit of the stick you wee on has some antibodies to the hormone, with blue beads attached
• The test trip has some more antibodies to the hormone stuck onto it (so that they can’t move)
• If you are pregnant, the hormone binded to the antibody and bead will get moved up the stick and will bind to the antibodies on the strip. So the blue beads get stuck on the strip, turning it blue
• If you’re not pregnant, the urine will still move up the stick carrying the blue beads, but there’s nothing to stick the blue beads onto the test strip, so it doesn’t go blue

Question 21

How can monoclonal antibodies be used to treat cancer?

Answer 21

1. Different cells in the body have different antigens on the cell surface
2. Cancer cells have a special type of antigen on their membranes, called tumour markers
3. Monoclonal antibodies can be made so that they bind to these tumour markers
4. An anti-cancer drug can be attached to these monoclonal antibodies, which stops the cancer cell growing and dividing
5. These antibodies are given to the patient through a drip
6. The drugs kills the cancer cells but doesn’t kill any normal body cells near the tumour

Question 22

How can monoclonal antibodies be used in laboratories and research to find specific substances?

Answer 22

1. They can bind to hormones and other chemicals in blood to measure their levels
2. They can test blood samples in laboratories for certain pathogens
3. They can locate specific molecules on a cell or tissue

Question 23

How can monoclonal antibodies be used to locate specific molecules on a cell or tissue?

Answer 23

1. Firstly, monoclonal antibodies are made that will bind to the specific molecules you’re looking for
2. The antibodies are then bound to a flourescent dye
3. If the molecules are present in the sample your analysing, the monoclonal antibodies will attach to them, and they can be detected using the dye

Question 24

What is an advantage of monoclonal antibodies?

Answer 24

• Cancer treatment - other cancer treatments (like chemotherapy andf radiotherapy) can affect normal body cells as well as killing cancer cells, whereas monoclonal antibodies target specific cells

Question 25

What is a disadvantage of monoclonal antibodies?

Answer 25

• They cause more side effects then were originally expected. Eg. fever, vomiting and low blood pressure.
• When first developed, scientists had thought that because they targeted a very specific cell, they wouldn’t create a lot of side-effects.
• So they are not as widely used as treatments as scientists had originally thought they might be

Question 26

Why do plants need mineral ions from the soil?

Answer 26

So that they don’t suffer deficiency symptoms

Question 27

What are nitrates needed for in plants?

Answer 27

To make proteins and therefore help with growth

Question 28

What can a lack of nitrates cause?

Answer 28

Stunted growth

Question 29

What are magnesium ions needed for?

Answer 29

Making chlorophyll which is needed for photosynthesis

Question 30

What can plants without enough magnesium suffer from?

Answer 30

Chlorosis and have yellow leaves

Question 31

What can infect plants?

Answer 31

Viral, bacterial and fungal pathogens
They can also be infested and damaged by insects. Eg. aphids

Question 32

What are the 6 common signs that a plant has a disease?

Answer 32

1. stunted growth
2. spots on the leaves
3. patches of decay
4. abnormal growths
5. malformed stems or leaves
6. discolouration

Question 33

How can signs of diseases on plants be indentified?

Answer 33

1. Looking up the signs in a gardening manual or gardening website
2. Taking the infected plant to a laboratory, where scientists can identify the pathogens
3. Using test kits that identify the pathogen using monoclonal antibodies

Question 34

What are the physical defences of a plant?

Answer 34

1. Most plant leaves and stems have a waxy cuticle, which provides a barrier to stop pathogens entering
2. Plants are surrounded by cell walls made from cellulose. These form a physical barrier against pathogens that made it through the waxy cuticle
3. Plants have layers of dead cells around their stems, eg the outer part of the bark on trees

Question 35

What are the chemical defences that plants have?

Answer 35

1. Some can produce antibacterial chemicals which kill bacteria (eg. mint plant and witch hazel)
2. Other plants produce poisons which can deter herbivores (eg. tobacco plants, foxgloves and deadly nightshade)