Cell Signaling Overview

To facilitate communication between cells.

Paracrine signaling involves a signaling cell acting on nearby target cells by secreting local regulators. An example is synaptic signaling between neurons.

Neurotransmitters are released by nerve cells, travel across the synapse, and bind to receptors on the target cell to trigger a response.

<ol> <li>Arrival of electrical impulse. 2. Release of neurotransmitters. 3. Neurotransmitters travel across synapse. 4. Response in target cell.</li> </ol> Signup and view all the answers

<p>Transcellular transport (without a plasmodesma linking the two cells).</p> Signup and view all the answers

<p>Juxtacrine signaling</p> Signup and view all the answers

<p>The bloodstream</p> Signup and view all the answers

<p>Autocrine signaling</p> Signup and view all the answers

<p>Plasmodesmata</p> Signup and view all the answers

<p>Antigen presenting cells</p> Signup and view all the answers

<p>Quorum sensing</p> Signup and view all the answers

<p>Paracrine signaling</p> Signup and view all the answers

<p>Slower</p> Signup and view all the answers

<p>Relay proteins bind to the phosphorylated tyrosines on the receptor, becoming activated themselves and triggering transduction pathways.</p> Signup and view all the answers

<p>When a ligand binds to the receptor, the ion channel opens, allowing specific ions to pass through the membrane. This rapid change in ion concentration inside the cell triggers a cellular response.</p> Signup and view all the answers

<p>Signaling molecules must be small enough and hydrophobic enough to pass through the cell's plasma membrane due to its phospholipid bilayer structure.</p> Signup and view all the answers

<p>Intracellular receptors are found in either the cytoplasm or the nucleus. They're activated when a signaling molecule passes through the plasma membrane and binds to the receptor protein.</p> Signup and view all the answers

<p>Transduction often involves multiple steps to help amplify the signal, ensuring a significant cellular response.</p> Signup and view all the answers

<p>The activated receptor activates another molecule, beginning a cascade of activations that propagate the signal.</p> Signup and view all the answers

<p>When the ligand dissociates from the ion channel receptor, the channel becomes inactive again, and the channel closes.</p> Signup and view all the answers

<p>This complex of receptor and ligand moves around and triggers a cellular response.</p> Signup and view all the answers

<p>Reception, where a ligand binds to a receptor protein.</p> Signup and view all the answers

<p>To receive a signal by binding to a specific ligand.</p> Signup and view all the answers

<p>A signaling molecule that binds to a receptor protein.</p> Signup and view all the answers

<p>G protein-coupled receptors, receptor tyrosine kinases (RTK)</p> Signup and view all the answers

<p>GTP when active (on) and GDP when inactive (off).</p> Signup and view all the answers

<p>The G protein binds to the activated receptor, exchanging GDP for GTP and becoming activated itself.</p> Signup and view all the answers

<p>Hydrolysis of GTP into GDP and inorganic phosphate (Pi).</p> Signup and view all the answers

<p>Signaling molecules bind to the receptor molecules, causing two receptor molecules (monomers) to dimerize.</p> Signup and view all the answers

<p>Each tyrosine kinase uses an ATP to add a phosphate to itself</p> Signup and view all the answers

<p>To provide the phosphate group that is added to the tyrosine kinases during activation, forming ADP in the process.</p> Signup and view all the answers

<p>Each active adenylyl cyclase molecule formed from epinephrine binding produces approximately 100 cAMP molecules.</p> Signup and view all the answers

<p>Each protein in the signaling pathway remains active long enough to activate multiple molecules in the subsequent step, leading to significant amplification.</p> Signup and view all the answers

<p>The response of a cell depends on its specific receptor proteins, relay proteins, and other components of its signaling pathways.</p> Signup and view all the answers

<p>Scaffolding proteins hold relay proteins together, facilitating their interaction and preventing signal diffusion, which increases efficiency.</p> Signup and view all the answers

<p>Inactivation mechanisms allow cells to reset and respond to new incoming signals, preventing prolonged or inappropriate activation.</p> Signup and view all the answers

<p>Apoptosis can be initiated by intracellular signals, such as irreversible DNA damage, or by extracellular signals from other cells.</p> Signup and view all the answers

<p>DNA is fragmented and the cell shrinks, forming blebs. The cell's components are then packaged into vesicles.</p> Signup and view all the answers

<p>Packaging cellular components protects neighboring cells from damage by preventing the unregulated release of potentially harmful substances.</p> Signup and view all the answers

<p>A protein kinase is an enzyme that transfers phosphate groups from ATP to a protein.</p> Signup and view all the answers

<p>Dephosphorylation is the removal of phosphate groups from proteins by protein phosphatases, rendering them inactive. It's important for turning off signal transduction pathways and allowing protein kinases to be reused.</p> Signup and view all the answers

<p>Second messengers are small, water-soluble molecules or ions that relay signals within the cell. Their size and solubility allow for rapid diffusion and amplification of the signal.</p> Signup and view all the answers

<p>Epinephrine binds to a G protein coupled receptor which activates a G protein which binds to adenylyl cyclase, increasing production of cAMP. cAMP then activates protein kinase A, which triggers cellular responses.</p> Signup and view all the answers

<p>A signaling molecule binds to a plasma membrane receptor which causes the formation of IP3. IP3 binds to an IP3 gated calcium channel in the ER membrane, causing it to open. Now Ca2+ ions can flow out into the cytosol leading to a cellular response.</p> Signup and view all the answers

<p>The 'first messenger' is the ligand that binds to the plasma membrane receptor protein.</p> Signup and view all the answers

<p>Signal amplification occurs through multiple steps in the transduction pathway. For example, one activated receptor can activate many relay molecules, each of which activates many more downstream molecules, leading to a large cellular response.</p> Signup and view all the answers

<p>Adenylyl cyclase is an enzyme that converts ATP into cAMP.</p> Signup and view all the answers

<p>IP3 gated calcium channels are located in the ER membrane. They open in response to IP3 binding, allowing $Ca^{2+}$ ions to flow out into the cytosol.</p> Signup and view all the answers

<p>Protein phosphatases remove phosphate groups from proteins (dephosphorylation), effectively inactivating them. This helps turn off the signal transduction pathway when the original signaling molecule is no longer present.</p> Signup and view all the answers

The process by which cells communicate using signaling molecules.

A signaling mechanism where nearby cells communicate by local regulators.

The process of communication between neurons via neurotransmitters across a synapse.

Chemical signals released by neurons to affect target cells across synapses.

Responses from neurotransmitters that can either increase or decrease cell activity.

The movement of substances across a membrane against their concentration gradient, requiring energy.

A process where molecules pass through a membrane via special proteins without energy input.

Cell signaling through direct contact between adjacent cells' membranes.

Special connections between animal cells that allow chemical signals to pass directly between cells.

Channels in plant cells that enable communication and transport between cells.

Hormonal communication where cells secrete hormones into the bloodstream to reach distant target cells.

When a cell signals itself by releasing a molecule that binds to its own receptor.

A process where bacteria communicate to assess their population density in an area.

Proteins that bind to phosphorylated tyrosines to activate transduction pathways.

Protein channels that open to allow ions through in response to ligand binding.

Receptors located in the cytoplasm or nucleus that bind to signaling molecules passing through the membrane.

A signaling molecule that binds specifically to another molecule, often a receptor.

The step in cell signaling where signals are amplified through multiple steps.

Series of molecular events triggered by receptor activation leading to cellular responses.

Tyrosine amino acids that have been modified to have a phosphate group, activating downstream processes.

The final outcome of a signal transduction pathway, resulting in a specific action by the cell.

Processes involving Reception, Transduction, and Response.

First step where a ligand binds to a receptor protein.

Protein that receives signals from ligands, located on target cells.

Receptors that work with G proteins and activate cellular responses.

GTP activates G proteins, GDP deactivates them.

Receptors that phosphorylate tyrosines after forming dimers upon ligand binding.

Process where receptor monomers join to form a dimer after ligand binding.

The addition of a phosphate group to a molecule, activating signaling pathways.

Receptors and G proteins activate enzymes to trigger cellular responses.

An enzyme that transfers phosphates from ATP to a protein.

A series of protein activations through phosphorylation in a signaling pathway.

Small molecules/ions that relay signals inside the cell after the first messenger binds.

A second messenger produced from ATP by adenylyl cyclase that activates protein kinase A.

A hormone that binds receptors to increase cAMP production in response to signals.

Important signaling molecules whose concentration changes can trigger cellular responses.

A signaling molecule that triggers calcium release from the endoplasmic reticulum.

Enzymes that remove phosphate groups from proteins, deactivating them.

The process where multiple steps in transduction boost the cell's response to a signal.

A hormone that triggers glycogen breakdown through signal transduction.

Cyclic AMP, a secondary messenger involved in signaling pathways.

Large relay proteins that hold multiple other proteins together to enhance signaling efficiency.

Programmed cell death, essential for eliminating damaged or unnecessary cells.

Triggers can be internal (like DNA damage) or external (from other cells).

Inactivation mechanisms that allow cells to reset and respond again to signals.

Molecular changes in signaling pathways must be temporary to prevent locking states.