Cell Signaling

Flashcards covering key concepts related to cell signaling and communication between cells.

What is the role of signaling in individual cells and multicellular organisms?

Individual cells need to sense and respond to their environment; in multicellular organisms, signaling determines specialized roles and coordinates functions.

What initiates signal transduction in target cells?

Signal transduction begins when a receptor on a target cell receives an incoming extracellular signal.

What are hormones in the context of cell signaling?

Hormones are extracellular signal molecules that are secreted into the bloodstream by endocrine cells to communicate throughout the body.

Describe paracrine signaling. What is autocrine signaling?

Paracrine signaling involves local diffusion of signal molecules to nearby cells. Autocrine signaling is when cells respond to local mediators they produce themselves.

How does neuronal signaling differ from other forms of cell communication?

Neuronal signaling delivers messages quickly and specifically to individual target cells through synapses using neurotransmitters.

What is contact-dependent signaling?

Contact-dependent signaling occurs when signaling and target cells make direct physical contact without the need for secreted molecules.

What types of molecules are classified as extracellular signal molecules?

Extracellular signal molecules can be proteins, peptides, nucleotides, steroids, fatty acid derivatives, or dissolved gases.

What is the function of the Notch receptor?

The Notch receptor acts as a transcription regulator that helps activate appropriate genes when cleaved and released in response to a signal.

Describe the two classes of extracellular signal molecules based on their ability to cross the plasma membrane.

The first class consists of large or hydrophilic molecules that use surface receptors; the second class consists of small or hydrophobic molecules that can cross the plasma membrane and activate intracellular receptors.

What is the significance of having many types of receptors in a single cell?

Having many different types of receptors allows a cell to be sensitive to a wide range of extracellular signals and to respond uniquely to combinations of signals.

What is the sequence of events following receptor activation during signal transduction?

Receptor activation generates new intracellular signals which relay the message downstream, ultimately altering the activity of effector proteins that affect cell behavior.

What determines a cell's response to signal molecules?

A cell's response depends on whether it possesses receptors for the specific signal molecule.

What is the role of signaling in individual cells and multicellular organisms?

Individual cells need to sense and respond to their environment; in multicellular organisms, signaling determines specialized roles and coordinates functions.

What initiates signal transduction in target cells?

Signal transduction begins when a receptor on a target cell receives an incoming extracellular signal.

What are hormones in the context of cell signaling?

Hormones are extracellular signal molecules that are secreted into the bloodstream by endocrine cells to communicate throughout the body.

Describe paracrine signaling. What is autocrine signaling?

Paracrine signaling involves local diffusion of signal molecules to nearby cells. Autocrine signaling is when cells respond to local mediators they produce themselves.

How does neuronal signaling differ from other forms of cell communication?

Neuronal signaling delivers messages quickly and specifically to individual target cells through synapses using neurotransmitters.

What is contact-dependent signaling?

Contact-dependent signaling occurs when signaling and target cells make direct physical contact without the need for secreted molecules.

What types of molecules are classified as extracellular signal molecules?

Extracellular signal molecules can be proteins, peptides, nucleotides, steroids, fatty acid derivatives, or dissolved gases.

What is the function of the Notch receptor?

The Notch receptor acts as a transcription regulator that helps activate appropriate genes when cleaved and released in response to a signal.

Describe the two classes of extracellular signal molecules based on their ability to cross the plasma membrane.

The first class consists of large or hydrophilic molecules that use surface receptors; the second class consists of small or hydrophobic molecules that can cross the plasma membrane and activate intracellular receptors.

What is the significance of having many types of receptors in a single cell?

Having many different types of receptors allows a cell to be sensitive to a wide range of extracellular signals and to respond uniquely to combinations of signals.

What is the sequence of events following receptor activation during signal transduction?

Receptor activation generates new intracellular signals which relay the message downstream, ultimately altering the activity of effector proteins that affect cell behavior.

What determines a cell's response to signal molecules?

A cell's response depends on whether it possesses receptors for the specific signal molecule.

Contrast "fast" and "slow" cell responses to signals.

Fast responses (< 1 sec to mins) usually involve changes in existing protein function; slow responses (mins to hours) require changes in gene expression and protein synthesis.

What are the four primary functions of intracellular signaling pathways?

1. Relay the signal; 2. Amplify the signal; 3. Integrate signals from multiple pathways; 4. Distribute the signal to effector proteins.

How do molecular switches function in signaling?

They toggle between active and inactive states, often through phosphorylation (via kinases) or by binding and hydrolyzing GTP (via GTP-binding proteins).

What is the role of scaffold proteins?

They act as docks to keep related signaling proteins in close proximity, ensuring signals are relayed with high speed, efficiency, and specificity.

How do small, hydrophobic signal molecules like steroid hormones interact with receptors?

They diffuse across the plasma membrane and bind to intracellular receptors (nuclear receptors) in the cytosol or nucleus to regulate gene transcription.