Cell Communications

These flashcards cover key concepts related to cell communications and signaling.

What is the role of cellular communication in cells?

Cells detect and respond to signals from their environment and other cells.

What response does a cell have to high glucose levels?

Cells synthesize enzymes needed to metabolize glucose.

What is the significance of ligands in cell signaling?

Signaling molecules that bind to receptors, triggering cellular responses.

What are agonists in the context of receptor activation?

Agonists are molecules that bind to receptors and lead to a conformational change of the receptor, activating it.

What characterizes enzyme-linked receptors?

Enzyme-linked receptors have an extracellular domain that binds signaling molecules and an intracellular domain that provides catalytic function.

What is the function of G-protein-coupled receptors (GPCR)?

GPCRs activate G-proteins to relay signals within the cell, leading to various cellular responses.

What occurs during signal transduction?

A signal is relayed through a series of molecules inside the cell, often amplifying the signal.

What are second messengers?

Small, non-protein signaling molecules that relay signals from cell surface receptors to target proteins inside the cell.

What is apoptosis?

Apoptosis is programmed cell death, where a cell orchestrates its own destruction for developmental and maintenance purposes.

What are the differences between the primary cell walls in plants and the extracellular matrix in animals?

Plant primary cell walls are mainly composed of carbohydrates, while the animal ECM consists primarily of proteins.

What is the importance of tight junctions in cell-cell interactions?

Create impermeable barriers that prevent the passage of substances between adjacent cells.

How does cell signaling maintain homeostasis?

Cell signaling allows cells to sense environmental changes and communicate with other cells to regulate cellular processes.

What is crosstalk in cell signaling?

The interaction where components of one signaling pathway affect another pathway, allowing for coordinated cellular responses.

How does a cell's response to signals differ among distinct cell types?

Different receptor expressions and intracellular pathways in various cell types lead to unique responses to the same signaling molecules.

What are the four main types of cell signaling based on distance?

The main types include paracrine (local), endocrine (long-distance via hormones), autocrine (self-signaling), and direct contact (juxtacrine).

How do ligand-gated ion channels function in cell signaling?

Upon ligand binding, these receptors open, allowing specific ions to pass through, altering membrane potential or intracellular ion concentrations.

What is the role of cyclic AMP (cAMP) as a second messenger?

cAMP often activates protein kinase A (PKA), which then phosphorylates various target proteins, leading to diverse cellular responses.

What is the benefit of signal amplification in signal transduction pathways?

Allows a small number of extracellular signaling molecules to trigger a large intracellular response, ensuring efficiency and sensitivity.

What are intracellular receptors and their function in cell signaling?

Intracellular receptors are located inside the cell (cytoplasm or nucleus). They bind to small, signaling molecules (like steroid hormones) that can pass through the plasma membrane, leading to changes in gene expression.

What is the role of protein kinases in signal transduction?

Catalyze the transfer of a phosphate group from ATP to specific proteins, regulating their activity and often activating a cascade of further signaling events.

How do protein phosphatases contribute to signal transduction?

Protein phosphatases remove phosphate groups from proteins, often deactivating them and serving to terminate or desensitize a cellular response, returning the protein to its original state.

What is the function of calcium ions (Ca^{2+}) as a second messenger in cell signaling?

Ca^{2+} ions can act as a second messenger, with their concentration quickly increasing in the cytoplasm in response to signals. This change in concentration can activate various proteins, leading to responses like muscle contraction, neurotransmitter release, or changes in gene expression.

What are gap junctions and their role in cell communication?

Gap junctions are channels that directly connect the cytoplasm of adjacent animal cells. This enables direct electrical and chemical communication.

What are antagonists in cell signaling?

Molecules that bind to receptors but block the receptor's activation, thereby inhibiting a cellular response.

How do hydrophilic signaling molecules typically interact with cells?

Hydrophilic signaling molecules usually bind to cell surface receptors because they cannot pass through the lipid bilayer of the plasma membrane.

What mechanisms are involved in terminating a cellular signal?

Signal termination involves receptor inactivation or removal, enzyme degradation, and dephosphorylation by phosphatases, resetting the cell's response.

What is a key characteristic of Receptor Tyrosine Kinases (RTKs)?

Enzyme-linked receptors that, upon ligand binding, dimerize and phosphorylate tyrosine residues on each other, initiating an intracellular signaling cascade.

What is a phosphorylation cascade in signal transduction?

A phosphorylation cascade is a series of signaling events where one protein kinase phosphorylates and activates another kinase, which then phosphorylates and activates a third, amplifying and relaying the signal.

What is the role of scaffolding proteins in signal transduction pathways?

Scaffolding proteins are adaptor proteins that bind multiple signaling proteins together, organizing them into complexes to enhance the efficiency and specificity of signal transduction.

Where are nuclear receptors typically found and what is their primary function?

Nuclear receptors are found in the cytoplasm or nucleus and, upon binding to lipid-soluble ligands, regulate gene expression.

What defines synaptic signaling?

Synaptic signaling is a specialized form of paracrine signaling where neurotransmitters are released from a neuron and diffuse across a small gap (synapse) to target cells, typically other neurons or muscle cells.

How do cells ensure specificity in their response to various signaling molecules?

Specificity is ensured by distinct receptor types (only specific ligands can bind), specific intracellular signaling pathways, and cell-type specific expression of effector proteins.

What is the function of an effector protein in a signaling pathway?

An effector protein is the final protein in a signaling pathway that carries out the cell's response, such as regulating gene expression, altering metabolism, or changing cell shape.