CHPT 11 CELL COMMUNICATION

What are the three stages of cell signaling?

Signal reception, signal transduction, and cellular response.

What happens during reception in cell signaling?

A molecule binds to a receptor protein on the cell surface

What happens during signal transduction?

The signal is relayed through a pathway of molecules

What happens during cellular response?

The cell produces a response in cytoplasm or nucleus

What is a ligand?

A signal molecule that binds to a receptor and changes its shape.

What are the three main types of membrane receptors?

G protein–coupled receptors (GPCRs), receptor tyrosine kinases (RTKs), and ion channel receptors.

What are G protein–coupled receptors (GPCRs)?

Cell surface transmembrane receptors that work with the help of a G protein

What is the function of receptor tyrosine kinases (RTKs)?

Catalyze the transfer of phosphate groups from ATP to other proteins.

How does a ligand-gated ion channel receptor work?

It acts as a gate, opening or closing when the receptor changes shape.

What type of chemical messengers can cross the plasma membrane freely?

Small hydrophobic molecules.

What is the role of protein kinases?

Add phosphates to proteins using ATP (phosphorylation).

What is a phosphorylation cascade?

A transduction pathway relaying signals by phosphorylating molecules in sequence

What do protein phosphatases do?

Remove phosphates from proteins (dephosphorylation).

What are second messengers?

Ions or small molecules that relay signals inside cells

What is the most common second messenger?

Cyclic AMP (cAMP)

What is an output response in cell signaling?

The cell’s response to extracellular signals.

What is usually the final activated molecule in a signaling pathway?

A transcription factor.

Where can cellular responses occur?

In the nucleus or cytoplasm

What are the four aspects of signal regulation?

Signal amplification, specificity of response, efficiency, and termination.