IB Biology Topic C2.1: Chemical Signalling Key Definitions

Cytokines are small proteins that mediate and regulate immune responses, inflammation, and cell signaling

A change in the membrane potential of the presynaptic neuron, making it more positive.

Epinephrine, also known as adrenaline, is a hormone and neurotransmitter produced by the adrenal glands.

A hormone and neurotransmitter, also known as adrenaline, produced by the adrenal glands that prepares the body for "fight or flight" responses during stress or excitement.

Feedback inhibition is a process where the end product of a metabolic pathway inhibits an enzyme involved in its own synthesis.

A large family of transmembrane receptors that detect external signals and activate intracellular G proteins, initiating cellular responses.

Hormones are chemical messengers secreted by endocrine glands into the bloodstream.

Hormones are chemical messengers that travel through the bloodstream to regulate various physiological processes.

Intracellular receptors are located within the cytoplasm or nucleus and interact with signalling molecules that can cross the plasma membrane.

A ligand is a molecule that binds to a specific site on a receptor protein.

Membrane potential is the difference in electrical charge between the inside and outside of a cell.

A negative feedback loop is a self-regulating system that detects changes in a variable and triggers responses to bring it back to a set point.

Neurotransmitters are chemical signals used by neurons to communicate across synapses, the tiny gaps between nerve cells or between nerve cells and other target cells.

A form of estrogen that promotes the growth of the uterine lining (endometrium) and regulates FSH and LH via feedback loops.

A process where an initial change causes further changes that amplify the original effect, making it stronger and self-reinforcing.

A communication system used by bacteria to coordinate group behaviors based on population density through the release and detection of signaling molecules.

A receptor is a protein that detects and responds to specific signals. They bind to signalling molecules(ligands) to initiate a cellular response.

A second messenger is a molecule that relays signals from the cell surface to the interior and amplifies the signal inside the cell.

Signal transduction is the process by which cells respond to external signals, converting them into a cascade of chemical responses inside the cell.

Signalling molecules are chemicals that transmit information between cells, triggering specific responses in target cells.

Transcription factors are proteins that control transcription by binding to specific DNA sequences.

Transmembrane receptors are embedded in the plasma membrane and interact with signalling molecules that cannot cross the membrane.

A class of transmembrane receptors that have an enzymatic domain capable of phosphorylating tyrosine residues on themselves or other proteins, initiating a signaling cascade inside the cell.