Drugs And Receptors

Question 1

What is the lock and key mechanism?

Answer 1

Drug- key will on,y bind to a specific receptor- lock

Question 2

Where are the targets for drug actions?

Answer 2

Receptors
Ion channels
Carrier/molecules pumps 
Enzymes
DNA

Question 3

What happens when a drug binds to a receptor?

Answer 3

Receptors are usually located in plasma membrane
Drug binds to receptor and signals change within the cell, alters cell properties
I.e. Change shape or secrete a chemical
Connected to second messenger such a G protein

Question 4

What happens when drug binds to ion channels?

Answer 4

Acts directly on ion channels
Cause the channels to open or close
Changes the electrical activity of the cell, which may lead to excitation or inhibition

Question 5

How is the carrier molecules/ pumps affected?

Answer 5

Carriers are proteins which allow substances to enter the cell
Drugs that interact with them either increase or decrease the uptake of the substance into the cell

Question 6

What happens when drugs bind to enzymes?

Answer 6

Either inhibit or excite the activity of the enzyme

Reactions are either slowed down or sped up

Question 7

What happens when drugs bind to DNA?

Answer 7

In the cell nucleus
Influence the way in which DNA message is transcribed or copied yo produce mRNA and proteins.
This can directly increase or decrease the synthesis of proteins

Question 8

What are other drug targets?

Answer 8

Selective toxicity- some drugs target proteins that are not found in the human cells such as penicillin: cell wall

Anti fungals- target a form of cholesterol not found in human membrane

Antivirals- block enzymes involved in replication or prevent virus entry into the host cell

Antihelmintics-drugs which expel parasitic worms from the body by stunning or killing them

Amoebicides- interfere with DNA of amoeba preventing them from reproducing example: metronidazole

Question 9

Give an example of s drug that binds to enzymes

Answer 9

Aspirin: blooms the cox 2, responsible for producing PG, which cause inflammation.
Viagra :blocks the enzymes responsible for relaxing smooth muscles in blood vessels, blood vessels dialyse casing more blood flow.

Question 10

Give an example of drug that binds to receptors

Answer 10

Salabutomol: b agonist, chemical structure similar to that of the hormone adrenaline. Causes airways to widen

Beta-blockers:stop adrenaline binding to receptors, high blood pressure or arrhythmias

Anti-histamine: blocks I stamina receptors in airways, nasal cavity, eyes, skin

Question 11

Give an example of drug that binds to ion channels

Answer 11

Local anaesthesia: block sodium channels, stop nerve impulse

Valium
Benzodiapines: anti anxiety, acts on GABA, slows down transmission to brain.

Question 12

Give an example of s drug that binds to pumps

Answer 12

Omaprazole: PPI, reduce acid secretion in stomach, trade gastric and duodenum ulcers, heart burn.

Cocaine: reduces the uptake of chemical transmitter noradrenaline, causing it to remain in the synapse. Stimulators effect.

Question 13

Give an example of s drug that binds to DNA

Answer 13

Hydrocortisone- steroids, reduces production of proteins that cause inflammation, suppress immune response

Question 14

Give an example of s drug that binds to foreign proteins

Answer 14

Penicillin: antibiotics. Weakens the cell wall of certain bacteria,stop them growing and dies

Ketocoanazole: anti fungal. Blocks production of ergosterol which forms the part of the fungal cell membrane, resulting in holes, cell content leaking out

Question 15

Name the two types of cell interaction

Answer 15

Agonist and antagonist

Question 16

What does agonists do?

Answer 16

Bind to receptor causing a response and often mimic the chemicals in the body

Example: b-agonist , Salabutomol: binds to receptor forms a complex, once complex formed its activated to cause a response

Insulin- insulin receptors
Nicotine- nicotine receptors

Question 17

What does the antagonist do?

Answer 17

Binds to receptor and stop chemicals from producing a response
May be reversible or irreversible
They compete with agonist for space, they occupy the space where the agnostic normally fits in. Thus when antagonist bind to the receptor the agonist can’t produce a full response
If the antagonist concentration is high enough, the agonist will be abolished.

Example: propranolol, competes with adrenaline to slow heart down
Antropine, compete with AcH to block AcH receptors

Question 18

What happens when a drug binds to a receptor?

Answer 18

Activates the second messengers, cascade of enzyme reactions and finally a response

Question 19

Give an example of a drug binding to a receptor and how a response occurs

Answer 19

Agonist I.e. Salabutomol, binds to b receptor causing the activation of G protein. This stimulus the second messenger adenylate cyclase enzyme to convert ATP to cAMP. cAMP converts inactive protein 1 to active protein 1. Causing protein 2 to lose calcium from the cytoplasm, causing a response of relaxation.

Question 20

What happens when a steroid binds to a nuclear receptor?

Answer 20

Steroids must enter the cell before causing a response.
They are lipid soluble and so can cross the cell membrane
Once in the sytoplasm, the steroids bind to free receptors to for a complex
2 complexes join together allowing them to enter the nucleus
Once inside, binds to DNA, genes are either switched on or off, if switched on RNA is produced, rescue protein production

Question 21

List the cellular response to drugs

Answer 21

Contraction
Secretion
Excitation
Inhibition
Interruption of cell cycle

Question 22

What is potency?

Answer 22

How much of the drug is needed to produce a response

High potency: small dose needed

Question 23

How do drugs work?

Answer 23

Bind to a particular part of a cell or tissue and produce a response
Normally proteins found in the cell