AP Biology Unit 4 – Cell Communication and Cell Cycle: Ultimate Study Notes

Why do cells communicate?

To coordinate activities

What determines whether a cell can respond to a signal?

Presence of the correct receptor

Why can different cells respond differently to the same signal?

They have different receptors and proteins

What is autocrine signaling?

A cell signaling itself

Which is an example of paracrine signaling?

Neurotransmitters affecting nearby cells

Endocrine signaling is characterized by:

Long-distance travel through bloodstream

Why are endocrine responses slower?

Signals must travel through bloodstream

What is a ligand?

A molecule that binds to a receptor

What happens when a ligand binds a receptor?

Receptor changes shape

What is the function of a receptor?

Receive signal and initiate response

What is the correct order of cell signaling?

Reception → Transduction → Response

What occurs during transduction?

Signal is relayed and amplified

What is signal amplification?

One signal activates many molecules

What do G protein-coupled receptors activate first?

G protein

What is a common second messenger?

cAMP

What happens in receptor tyrosine kinases (RTKs)?

Dimerization and phosphorylation

Why are RTKs important in cancer?

Mutations can cause uncontrolled growth

Ligand-gated ion channels result in:

Rapid ion movement across membrane

Which molecules use intracellular receptors?

Steroid hormones

What is the main effect of intracellular signaling?

Changes in gene expression