L13: Activation and Inhibition of Proteins #1

Question 1

These are harmful proteins.

Answer 1

Toxins/poisons

Question 2

These are beneficial proteins.

Answer 2

Medicines/drugs

Question 3

What are the 4 main steps of protein activation/inhibition?

Answer 3

1) chemical substance is present
2) chemical substance binds to target protein
3) causes activation or inhibition
4) changes to cellular response

Question 4

This is the terminology for when a chemical substance interacts with its target protein

Answer 4

Binding/reception

Question 5

These are compounds that bind to an enzyme and reduces its activity

Answer 5

Inhibitors

Question 6

This controls chemical signalling between and within cells.

Answer 6

Receptor

Question 7

These generally bind substrates to one active site. Changes substrates into product.

It can be membrane bound or free in the cytosol.

Answer 7

Enzymes

Question 8

These have several binding sites that bind ligands. It usually releases ligand unchanged.

It can be membrane bound or free in the cytosol.

Answer 8

Receptors

Question 9

_______ and __________ can be activated and inhibited and used as drug targets.

Answer 9

Enzymes; receptors

Question 10

What are the 3 main classes of receptor?

Answer 10

1) ligand-gated ion channel
2) G-protein coupled receptor
3) receptor tyrosine kinase (RTK)

Question 11

This is the general term given to a chemical substance that specifically binds to a receptor.

Answer 11

Ligand

Question 12

True or false. Ligands can’t be proteins or large peptides.

Answer 12

False. Ligands range from small molecules, to large peptides and even proteins.

Question 13

These are ligands that are produced in the body.

Answer 13

Endogenous ligands

Question 14

These are ligands that come from the external environment. Examples are drugs and toxins.

Answer 14

Exogenous ligands.

Question 15

True or false. Only some ligands make chemical contacts with their specific receptors.

Answer 15

False. All ligands make chemical contacts with their receptors.

Question 16

This is known as the gate-keeper of cellular activity, controlling it from the cell surface.

Answer 16

Receptor

Question 17

True or false. A ligand does not usually have to pass through the outer membrane when going from external to internal body environment.

Answer 17

True

Question 18

True or false. Activation will only happen when ligands are not paired with their appropriate receptors.

Answer 18

False. Ligands have a specificity; meaning, activation/inhibition will only happen if the pairing between ligand and receptor is correct.

Question 19

Why is binding to receptor proteins a significant process when making drugs?

Answer 19

Because having specific receptor proteins means that we can make drugs that bind only to certain receptor targets.

Question 20

This is a chemical substance/ligand that binds to a receptor and activates it.

Answer 20

Agonist

Question 21

When a receptor is activated, it will undergo a what to enable the function of the receptor?

Answer 21

A conformational shape change

Question 22

This is the process where messages are passed on through the cell.

Answer 22

Signal transduction

Question 23

True or false. Different receptors use the same types of relay molecules to pass on messages.

Answer 23

False. Different receptors use different relay molecules

Relay molecules - are molecules that relay the message to initiate cellular activity.

Question 24

A chemical substance (ligand) that binds to a receptor and prevents activation by an agonist is called an..

Answer 24

Antagonist

Question 25

True or false. Antagonist blocks the binding of an agonist; resulting in competition at the active site.

Answer 25

True. It occupies the active site first before the agonist to stop the agonist from binding

Question 26

True or false. When an antagonist binds to an active site, signal transduction can still occur.

Answer 26

False. When the antagonist binds, the agonist can’t bind - which means that the enzyme will not be activated. If the enzyme is not activated, this means that signal transduction cannot occur.

Question 27

Explain how adrenaline causes cellular changes.

Answer 27

1) Acts as an agonist to activate B-adrenergic receptor (a GPCR) 2) Signal transduction (causes activation) 3) Results in bronchodilation

Question 28

What is the receptor adrenaline binds to? What kind of receptor is it?

Answer 28

B-adrenergic receptor. It is a GPCR receptor.

Question 29

Are endogenous ligands more likely to be agonist or antagonist?

Answer 29

Agonist. Because they were already made in the body, so are specified to activate receptors in the body.

Question 30

True or false. Ligand receptor interactions are non-specific.

Answer 30

False. They are highly specific; remember pairing can only occur between the right ligand and receptor pair - otherwise, activation will not occur.

Question 31

Explain how insulin can cause cellular changes.

Answer 31

1) Insulin acts as an agonist to activate insulin receptor (RTK) 2) Signal transduction occurs. 3) Results in glucose uptake

Question 32

What type of receptor does insulin bind to?

Answer 32

A RTK (insulin receptor)

Question 33

Where are most receptors found on the cell?

Answer 33

The outside of the cell. This is so they are able to detect extracellular changes and conduct messages on the inside to form the appropriate cellular responses.