Chapter 8 Cell Communication

What is cell communication?

The process by which cells respond to incoming signals and produce outgoing signals.

Name the five common ways cells communicate based on distance.

1. Direct intercellular signaling, 2. Contact-dependent signaling, 3. Autocrine signaling, 4. Paracrine signaling, 5. Endocrine signaling.

What is a ligand?

A signaling molecule that binds to a receptor.

Describe receptor activation.

Receptor activation occurs when a ligand binds noncovalently to its receptor, causing a conformational change.

What are cell surface receptors?

Receptors embedded in the plasma membrane that detect extracellular signals.

List the three types of cell surface receptors.

1. Enzyme-linked receptors, 2. G-protein-coupled receptors, 3. Ligand-gated ion channels.

What do enzyme-linked receptors typically include?

An extracellular signal-binding domain and an intracellular catalytic domain.

How do G-protein-coupled receptors function?

They interact with G proteins, causing dissociation of the subunits that then interact with other proteins.

What is the role of ligand-gated ion channels?

They open to allow the flow of ions across the membrane upon ligand binding.

What function do intracellular receptors perform?

They bind small and hydrophobic signal molecules, typically leading to changes in gene expression.

Define autocrine signaling.

A type of signaling where cells secrete signaling molecules that bind to their own surface receptors.

What is endocrine signaling?

A signaling method where hormones are released into the bloodstream to affect distant target cells.

Explain signal transduction.

The process by which a signal is transmitted through a cell via a cascade of molecular events.

What happens to a receptor after a ligand is released?

The receptor reverts to its inactive conformation.

What is the structure of a ligand-receptor complex?

It is a stable, finite complex formed during ligand binding that will eventually dissociate.

How does phosphorylation affect a protein?

Phosphorylation alters the structure and function of a protein.

What is the significance of Kd in receptor-ligand interactions?

Kd represents the dissociation constant, indicating the affinity between a receptor and its ligand.

What are the roles of chemical signals in cells?

Chemical signals can trigger cell responses to environmental changes and coordinate communication in multicellular organisms.

Describe the three stages of cell signaling.

1. Receptor activation, 2. Signal transduction, 3. Cellular response.

What are the characteristics of intracellular receptors?

They are located in the cytosol or nucleus and bind signals that are small and hydrophobic.