Enzyme Inhibition: poisons and medicinal drugs

Question 1

Give another name for poisons.

Answer 1

Toxins

Question 2

Give the molecular formula of potassium cyanide.

Answer 2

KCN

Question 3

What gas is produced when KCN is hydrolysed?

Answer 3

hydrogen cyanide

Question 4

What can HCN do easily?

Answer 4

Dissociate into H+ ions and CN-

Question 5

CN- then binds irreversibly to an enzyme found where?

Answer 5

In the mitochondria.

Question 6

What does cyanide prevent form happening?

Answer 6

It inhibits the final stage of aerobic respiration.

Question 7

Why does aerobic respiration stop after the ingestion of cyanide?

Answer 7

The final stage of aerobic respiration is inhibited by cyanide, meaning that earlier stages cannot run and aerobic respiration stops.

Question 8

The venom in a green mamba snake inhibits what enzyme?

Answer 8

Acetylcholinesterase

Question 9

Why is acetylcholinesterase important?

Answer 9

It breaks down acetylcholine which is used at neuromuscular synapses. If this neurotransmitter is not broken down it stays attached to the receptors on the muscle membrane and keeps them contracted.

Question 10

What is another term for “The muscles remain contracted”

Answer 10

Paralysis.

Question 11

If the muscles involved in breathing are paralysed what will happen to the victim?

Answer 11

They will die from suffocation.

Question 12

What is the acid inside of aspirin?

Answer 12

Salicylic acid

Question 13

What does the salicylic acid in aspirin bind to?

Answer 13

Enzymes that catalyse the formation of prostaglandins.

Question 14

What are prostaglandins?

Answer 14

Cell signalling molecules produced by cells when tissues are infected or damaged.

Question 15

What do prostaglandins do?

Answer 15

Make nerve cells more sensitive to pain and increase swelling during inflammation.

Question 16

What else can aspirin do?

Answer 16

Reduce blood clots forming in blood vessels, many people take a small dose to reduce the risk of strokes.

Question 17

Why are children under 12 not allowed to take aspirin?

Answer 17

Aspirin can damage their stomach lining.

Question 18

What are the chemicals identified as cardiac glycosides also known as?

Answer 18

Digitalis
Digitoxin
Digitalin
Digoxin

Question 19

Where are cardiac glycosides naturally found?

Answer 19

From purple foxglove leaves.

Question 20

What do cardiac glycosides do?

Answer 20

They inhibit the sodium potassium pump in the cell membranes of heart-muscle cells and allows more calcium ions to enter the cells.

Question 21

What do calcium ions do?

Answer 21

Increase muscle contraction, and this strengthens the heart beat.

Question 22

What are ACE inhibitors?

Answer 22

Medical drugs that inhibit the angiotensin converting enzyme (ACE).

Question 23

What does ACE do?

Answer 23

It operates in a metabolic pathway that ultimately increases your blood pressure.

Question 24

What are ACE inhibitors used for?

Answer 24

To lower blood pressure in patients with hypertension who cannot take beta-blockers.
To treat heart failure.
To minimise the risk of a second heart attack or stroke in patients who have suffered from a myocardial infarction.

Question 25

What are protease inhibitors used to treat?

Answer 25

Some viral infections.

Question 26

Give two examples of protease inhibitors.

Answer 26

Amprenavir

Ritonavir

Question 27

What do protease inhibitors prevent?

Answer 27

The replication of virus particles within the host cells, by inhibiting protease enzymes so that the viral coats cannot be made.

Question 28

Through what process do protease inhibitors often work?

Answer 28

By competitive inhibition.

Question 29

What is the name of the drugs used to treat HIV?

Answer 29

Nucleoside reverse transcriptase inhibitors.

Question 30

How do NRTI drugs work?

Answer 30

They inhibit enzymes making DNA using the viral RNA as a template.