2.5 Cell Signalling Flashcards
Why do cells need to communicate with each other?
To control processes within the body and respond to changes in environment
What do cells communicate using?
Messenger molecules (e.g. Hormones, neurotransmitters)
What are the steps involved in cell signalling?
- 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
What messengers are able to pass straight through the membrane? Why?
Steroid hormones such as testosterone
Because they are small and non polar enough
Because most messengers are unable to pass through the membrane what must they bind to?
Membrane bound receptors
In order for cells to survive what must cells do?
Communicate with each other
What do proteins in the cell membrane act as?
Receptors for Messenger molecules
When do receptor proteins have and what does this mean for the messenger molecules?
They have a specific shape
Only messenger molecules with a complimentary shape can bind
What do different cells have?
Different types of receptors that respond to different messenger molecules
What is a cell called that responds to a particular messenger molecule?
A target cell
Give an example of a messenger molecule that binds to a target cell:
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
What are many membrane bound receptors and what are they often called?
Integral proteins often called transmembrane receptors
Name the three parts/domains of transmembrane receptors:
- extra cellular domain
- transmembrane domain
- intercellular domain
What is the extra cellular domain?
The part that sticks out of the cell to which a messenger binds
What is the transmembrane domain?
The part buried within the membrane
What is the intercellular domain?
The part that sticks into the cell and relays the signal to the cell
How do many drugs work?
By binding to receptors in cell membranes
What do drugs that bind to receptors do?
- trigger a response
* or block the receptor preventing it from working
What are agonists?
Drugs that bind to receptors and mimic the bodies normal messengers
Give an example of an agonistic drug:
Ritalin which is used to treat ADHD by increasing dopamine levels in the body
What are antagonists?
Drugs that bind to receptors and block the bodies normal messengers
Give an example of an antagonist drug:
Haloperidol used to treat schizophrenia by suppressing dopamine receptors
Are antihistamines agonists or antagonists?
Antagonists
What do antihistamines do?
Block histamine receptors in cell surfaces, preventing histamine binding to the cell causing inflammation
How is histamine released and what does it do?
- release is caused by cell damage
- histamine binds to receptors in the surface of other cells causing inflammation
