Cell Signaling & Regulation – Vocabulary Flashcards

A comprehensive set of vocabulary flashcards covering core terms and processes involved in cell signaling, second messengers, signal amplification, and blood-glucose regulation.

Cell Signaling

Process by which cells detect, interpret, and respond to external and internal messages (signals).

Environmental Signaling

Reception of physical factors such as light, temperature, and pressure by cells or organisms.

Phototropism

Directional growth of a plant toward light due to uneven auxin distribution.

Signal Molecule (Ligand)

Chemical messenger that binds to a receptor to initiate a signaling pathway.

Conformational Change

Alteration of a receptor’s 3-D shape upon ligand binding that triggers downstream events.

Signal Transduction Cascade

Series of molecular interactions that relay and amplify a signal from receptor to response.

Cell Response

Physiological change produced after a signaling pathway is activated (e.g., gene expression, enzyme activation).

Juxtacrine Signaling

Cell-to-cell communication occurring through direct contact of membrane-bound molecules.

Paracrine Signaling

Local communication in which a cell releases signals to nearby target cells.

Autocrine Signaling

Cell releases a signal that binds to receptors on its own surface, affecting itself.

Endocrine Signaling

Long-distance signaling via hormones that travel through the bloodstream to distant cells.

Intracellular Receptor

Signal receptor located inside the cell; binds small or hydrophobic ligands that can cross membranes.

Membrane Receptor

Protein embedded in the plasma membrane that binds extracellular ligands.

Ligand-Gated Ion Channel

Membrane receptor that opens or closes an ion channel in response to ligand binding.

Protein Kinase Receptor

Membrane-spanning receptor possessing enzymatic activity that phosphorylates target proteins upon activation.

G Protein–Coupled Receptor (GPCR)

Seven-pass membrane receptor that activates a heterotrimeric G protein when bound by ligand.

Second Messenger

Small molecule (e.g., cAMP, Ca²⁺, IP₃) that propagates and amplifies signals within the cytoplasm.

Signal Amplification

Phenomenon where one ligand–receptor event generates a large intracellular response (e.g., 1 epinephrine → 10,000 glucose).

Mitogen

Signal molecule that stimulates cell division.

RAS

Small GTPase that activates MAPK cascade; mutations locking it ‘on’ drive uncontrolled proliferation.

MAPK Cascade

Mitogen-activated pathway: MAP3K → MAP2K → MAPK, culminating in changes to gene expression.

Phospholipase C (PLC)

Enzyme that cleaves PIP₂ into IP₃ and DAG, generating second messengers.

PIP₂

Membrane phospholipid precursor for second messengers IP₃ and DAG.

Diacylglycerol (DAG)

Hydrophobic second messenger remaining in the membrane after PIP₂ cleavage; activates PKC.

Inositol 1,4,5-trisphosphate (IP₃)

Hydrophilic second messenger that triggers Ca²⁺ release from the smooth ER.

Calcium Ion (Ca²⁺)

Versatile second messenger released from organelles to regulate many cellular processes.

Adenylyl Cyclase

Enzyme activated by Gα that converts ATP to cAMP.

Cyclic AMP (cAMP)

Hydrophilic second messenger that activates protein kinase A.

Protein Kinase A (PKA)

cAMP-dependent kinase that phosphorylates targets involved in metabolism and gene regulation.

Glycogen Phosphorylase

Enzyme that breaks down glycogen into glucose-1-phosphate; activated by phosphorylation.

Phosphorylase Kinase

Kinase that activates glycogen phosphorylase through phosphorylation.

Glycogen Synthase

Enzyme that synthesizes glycogen; inactivated by PKA-mediated phosphorylation.

Receptor Recycling

Return of endocytosed receptors to the plasma membrane to reset signaling capacity.

Phosphodiesterase

Enzyme that degrades cAMP to AMP, terminating the cAMP signal.

Ion Channel Opening

Fastest cell response type, altering membrane potential or ion homeostasis.

Enzyme Activity Modulation

Intermediate-speed response changing metabolic pathways via phosphorylation or allosteric effects.

Gene Expression Change

Slow but long-lasting response involving transcriptional activation or repression.

Insulin Receptor

Receptor tyrosine kinase that initiates a cascade leading to glucose uptake and storage.

Insulin Receptor Substrate (IRS)

Adaptor protein phosphorylated by the insulin receptor; recruits downstream signaling molecules.

PKB / Akt

Serine/threonine kinase activated by PIP₃; promotes glucose uptake and glycogen synthesis.

Diabetes Mellitus Type 1

Autoimmune destruction of pancreatic β-cells leading to absolute insulin deficiency.

Diabetes Mellitus Type 2

Insulin resistance in target tissues requiring higher insulin levels for normal glucose uptake.

Signal Pathway Reset

Combination of receptor recycling, chemical reversal of intermediates, and ligand removal to terminate signaling.

Auxin

Plant hormone that redistributes during phototropism to promote differential cell elongation.