Suggested pre-class questions:
1. Define the following terms from your reading:
Signaling molecule
Receptor
G protein-coupled receptor
2nd messenger
Target cell
Agonist
Antagonist
2.
a) Must a signaling molecule enter a target cell in order to trigger a response?
b) Explain your answer in part a.
3. Circle the true statements below:
One type of signaling molecule triggers one and only one response.
One type of signaling molecule can trigger a response from many different types of cells.
A single signaling cell can produce only one type of signaling molecule.
A cell signaling pathway can be turned on, but not off.
Cellular responses can be triggered by molecules made by the body, molecules ingested, or
molecules injected.
Suggested pre-class questions With answers:
1. Define the following terms from your reading:
Signaling molecule
A molecule that causes a response in target cells.
Receptor
The molecule on a target cell that a signaling molecule must interact with in order to
cause a response.
G protein-coupled receptor
A receptor on the surface of a cell that passes a signal into the cell by activating a G
protein.
2nd messenger
When a G protein-coupled receptor is activated, the G protein activates a 2nd messenger.
The second messenger is a molecule within the target cell that amplifies the signal from
the receptor.
Target cell
A cell that responds to a particular signaling molecule.
Agonist
A molecule that binds the receptor and activates a response.
Antagonist
A molecule that partially binds the receptor and prevents the signaling molecule from
binding.
2.
a) Must a signaling molecule enter a target cell in order to trigger a response?
No. (Not always.)
b) Explain your answer in part a.
A few do, but most interact with a receptor on the surface of the target cell.
3. Circle the true statements below:
F
One type of signaling molecule triggers one and only one response.
T
One type of signaling molecule can trigger a response from many different types of cells.
F
A single signaling cell can produce only one type of signaling molecule.
F
A cell signaling pathway can be turned on, but not off.
T
Cellular responses can be triggered by molecules made by the body, molecules ingested, or
molecules injected.