2.5 Cell Signalling

Question 1

Why do cells need to communicate with each other?

Answer 1

To control processes within the body and respond to changes in environment

Question 2

What do cells communicate using?

Answer 2

Messenger molecules (e.g. Hormones, neurotransmitters)

Question 3

What are the steps involved in cell signalling?

Answer 3

• 1 cell releases messenger molecule
• molecule travels to another cell (e.g in the blood)
• messenger molecule is detected by the cell as it binds to a receptor on its membrane

Question 4

What messengers are able to pass straight through the membrane? Why?

Answer 4

Steroid hormones such as testosterone

Because they are small and non polar enough

Question 5

Because most messengers are unable to pass through the membrane what must they bind to?

Answer 5

Membrane bound receptors

Question 6

In order for cells to survive what must cells do?

Answer 6

Communicate with each other

Question 7

What do proteins in the cell membrane act as?

Answer 7

Receptors for Messenger molecules

Question 8

When do receptor proteins have and what does this mean for the messenger molecules?

Answer 8

They have a specific shape

Only messenger molecules with a complimentary shape can bind

Question 9

What do different cells have?

Answer 9

Different types of receptors that respond to different messenger molecules

Question 10

What is a cell called that responds to a particular messenger molecule?

Answer 10

A target cell

Question 11

Give an example of a messenger molecule that binds to a target cell:

Answer 11

Glucagon- a hormone released when there isn’t enough glucose in the blood. It binds to receptors on liver cells causing the cell to break down stores of glycogen to glucose

Question 12

What are many membrane bound receptors and what are they often called?

Answer 12

Integral proteins often called transmembrane receptors

Question 13

Name the three parts/domains of transmembrane receptors:

Answer 13

• extra cellular domain
• transmembrane domain
• intercellular domain

Question 14

What is the extra cellular domain?

Answer 14

The part that sticks out of the cell to which a messenger binds

Question 15

What is the transmembrane domain?

Answer 15

The part buried within the membrane

Question 16

What is the intercellular domain?

Answer 16

The part that sticks into the cell and relays the signal to the cell

Question 17

How do many drugs work?

Answer 17

By binding to receptors in cell membranes

Question 18

What do drugs that bind to receptors do?

Answer 18

• trigger a response

* or block the receptor preventing it from working

Question 19

What are agonists?

Answer 19

Drugs that bind to receptors and mimic the bodies normal messengers

Question 20

Give an example of an agonistic drug:

Answer 20

Ritalin which is used to treat ADHD by increasing dopamine levels in the body

Question 21

What are antagonists?

Answer 21

Drugs that bind to receptors and block the bodies normal messengers

Question 22

Give an example of an antagonist drug:

Answer 22

Haloperidol used to treat schizophrenia by suppressing dopamine receptors

Question 23

Are antihistamines agonists or antagonists?

Answer 23

Antagonists

Question 24

What do antihistamines do?

Answer 24

Block histamine receptors in cell surfaces, preventing histamine binding to the cell causing inflammation

Question 25

How is histamine released and what does it do?

Answer 25

• release is caused by cell damage

- histamine binds to receptors in the surface of other cells causing inflammation