Signal Transduction Pathways - AP Biology

Nearby cells. Signal diffuses locally to affect neighboring cells.

To remove phosphate groups from proteins. They reverse kinase action and help terminate signaling pathways.

Gene expression. Signals often activate transcription factors that regulate gene transcription.

Signal transduction. It encompasses detection, transduction, and cellular response to signals.

Opening or closing of the channel. Ligand binding changes channel conformation to allow ion flow.

Intracellular receptors. These receptors act as ligand-activated transcription factors.

Regulation of gene transcription. Hormone-receptor complex binds DNA and regulates gene transcription.

Signal termination. Prevents continuous signaling by degrading messengers or inactivating components.

Receptor-ligand specificity. Only matching ligand-receptor pairs trigger responses in target cells.

Interaction between different signaling pathways. Pathways can influence each other, creating integrated cellular responses.

Calcium ions (Ca²⁺). Released from ER stores, it activates many enzymes and processes.

Muscle contraction. Calcium release triggers actin-myosin interaction for muscle contraction.

Cyclic AMP (cAMP). It activates protein kinase A and regulates many metabolic processes.

To bind the ligand and initiate a cellular response. Receptors undergo conformational changes when bound to transmit signals.

To phosphorylate target proteins, altering their activity. Phosphorylation changes protein shape and function, activating or inhibiting them.

To relay signals from receptors to target molecules inside the cell. They amplify signals and allow for rapid cellular responses.

A series of molecular events that lead to a cellular response. It converts extracellular signals into intracellular responses through three main steps.

Dimerization and autophosphorylation. Two receptors pair up and phosphorylate each other's tyrosine residues.

Protein kinase A (PKA). cAMP binds to and activates this key regulatory kinase.

Production of IP₃ and DAG. PLC splits PIP₂ into these two distinct second messenger molecules.

Receptor upregulation. More receptors increase the cell's ability to detect weak signals.

To activate protein kinase C (PKC). DAG remains in membrane and activates this important kinase.

To increase the strength of the signal and ensure a robust response. One signal molecule can activate many downstream effectors in cascade fashion.

To act as a signaling molecule that diffuses across membranes. NO diffuses freely and activates guanylyl cyclase in target cells.

To bind calcium ions and activate enzymes. This calcium-binding protein regulates many calcium-dependent processes.

The phosphoinositide pathway. PLC cleaves PIP₂ to generate two important second messengers.

The adrenergic signaling pathway. Epinephrine and norepinephrine activate this fight-or-flight response.

A molecule that binds to a receptor to initiate signaling. Specific binding ensures only appropriate cells respond to signals.

The signaling molecule or ligand. It's the external signal that triggers the pathway by binding to receptors.