Chapters 7-8: Monoclonal antibodies and plant disease

Question 1

What is the difference between a bacteriocidal and a bacteriostatic antibiotic?

Answer 1

Bacteriocidal antibiotics kill bacteria by dissolving their cell walls, bacteriostatic antibiotics prevent bacteria from growing

Question 2

How do plant diseases affect humans?

Answer 2

TMV/Rice blast/nematode worms destroy crops, which can lead to mass starvation

Question 3

What happens if a plant doesn’t have enough magnesium ions?

Answer 3

They can’t produce chlorophyll (which contains magnesium), so their leaves turn yellow and they suffer from stunted growth due to the fact that they can’t photosynthesise

Question 4

What happens if a plant doesn’t have enough nitrate ions?

Answer 4

It can’t make protein and suffers from stunted growth

Question 5

What are some symptoms of plant infection?

Answer 5

Stunted growth, spots, rotting, malformation, discolouration, pests

Question 6

How do plants prevent infection?

Answer 6

Thick cell walls and waxy cuticles make viral infection of cells harder, bark is dead and acts as skin

Question 7

How do plants fight off infections?

Answer 7

Mint and other plants synthesise their own antibacterial compounds, which are now used as human antiseptics

Question 8

How do plants prevent being eaten?

Answer 8

(Poison ivy, deadly nightshade) Producing poisonous chemicals such as digitalis
Spines and thorns
Folding leaves when touched to make grasshoppers fall off
Spots that look like butterfly eggs (to discourage butterflies from laying their eggs there)

Question 9

What is the first stage of drug development?

Answer 9

Computer modelling (seeing how it might interact with the body and with other chemicals)

Question 10

What is the second stage of drug development?

Answer 10

Testing on animals or tissues grown in petri dishes

Question 11

What is the third stage of drug development?

Answer 11

Testing on humans to identify safe dosages, testing efficacy on sick patients (how well it works), given to a large number of patients to finalise safe doses and efficacy

Question 12

What is a double blind trial?

Answer 12

A trial where both the doctor and the patient do not know who has been given the trial and who has been given the placebo. This eliminates the placebo effect

Question 13

How does antibiotic resistance work?

Answer 13

Antibiotics kill all the normal bacteria, leaving behind the resistant ones, which go on to reproduce. Always finish the full course of antibiotics

Question 14

What are monoclonal antibodies?

Answer 14

Antibodies that are clones of other antibodies, created in laboratories.

Question 15

How are monoclonal antibodies produced?

Answer 15

An antigen is injected into a mouse. The mouse’s immune response begins and after a few days its white blood cells produce antibodies specific to the injected antigen. Spleen cells are then collected from the mouse, and fused with cancerous white blood cells (myeloma cells) to form hybridoma cells. These cells are placed in a medium that only allows hybridoma cells to survive. Since the hybridoma cells are cancerous, they keep dividing and producing antibodies indefinitely when grown in culture. The antibodies are isolated by centrifugation, filtration and chromatography

Question 16

What does the word “monoclonal” mean?

Answer 16

Identical clones of one

Question 17

How do pregnancy tests work?

Answer 17

Monoclonal antibodies to HCG (a hormone present in the urine of pregnant women) are stuck to the ends of a small strip of paper which a woman urinates onto. When HCG binds to these antibodies, they change colour, creating a blue line on the pregnancy test device

Question 18

What is the function of the spleen?

Answer 18

To produce and destroy red blood cells

Question 19

How are monoclonal antibodies used for diagnostics?

Answer 19

They are used to detect chlamydia and AIDS. They can also be used to test for hormones in the blood. The mechanism is similar to what happens in pregnancy tests, but the antibodies emit UV light instead of blue light

Question 20

How are monoclonal antibodies used to treat diseases?

Answer 20

Monoclonal antibodies can help the immune system attack cancerous cells, stop the cells dividing, or deliver toxic drugs or radiation to them

Question 21

What is tobacco mosaic virus (TMV)?

Answer 21

A virus that infects tobacco and tomato plants, turns leaves black and reduces the plant’s ability to photosynthesise. It can survive in soil. Pseudomonas syringae does the same thing, but also increase the susceptibility to frost damage. Rose black spot does the same thing but affects roses instead

Question 22

How can humans prevent plant diseases?

Answer 22

Sterilising tools, burning infected plants, antifungal spray