Chapter 11 - Cell Communication Flashcards
apoptosis
A type of programmed cell death, which is brought about by activation of enzymes that break down many chemical components in the cell.
signal transduction pathway
A series of steps linking a mechanical, chemical, or electrical stimulus to a specific cellular response.
local regulator
A secreted molecule that influences cells near where it is secreted.
hormone
In multicellular organisms, one of may types of secreted chemicals that are formed in specialized cells, travel in body fluids, and act on specific target cells in other parts of the body, changing the target cells’ functioning. Hormones are thus important in long-distance signaling.
ligand
A molecule that binds specifically to another molecule, usually a larger one.
G protein-coupled receptor (GPCR)
A signal receptor protein in the plasma membrane that responds to the binding of a signaling molecule by activating a G protein. Also called a G protein-linked receptor.
G protein
A GTP-binding protein that relays signals from a plasma membrane signal receptor, known as a G protein-coupled receptor, to other signal transduction proteins inside the cell.
receptor tyrosine kinase (RTK)
A receptor protein spanning the plasma membrane, the cytoplasmic (intracellular) part of which can catalyze the transfer of a phosphate group from ATP to a tyrosine on another protein. Receptor tyrosine kinases often respond to the binding of a signaling molecule by dimerizing and then phosphorylating a tyrosine on the cytoplasmic portion of the other receptor in the dimer. The phosphorylated tyrosines on the receptors then activate other signal transduction proteins within the cell.
ligand-gated ion channel
A transmembrane protein containing a pore that opens or closes as it changes shape in response to a signaling molecule (ligand), allowing or blocking the flow of specific ions; also called an ionotropic receptor.
protein kinase
An enzyme that transfers phosphate groups from ATP to a protein, thus phosphorylating the protein.
protein phosphatase
An enzyme that removes phosphate groups from (dephosphorylates) proteins, often functioning to reverse the effects of a protein kinase.
second messenger
A small, nonprotein, water-soluble molecule or ion, such as a calcium ion (Ca2+) or cyclic AMP, that relays a signal to a cell’s interior in response to a signaling molecule bound by a signal receptor protein.
cyclic AMP (cAMP)
Cyclic adenosine monophosphate, a ring-shaped molecule made from ATP that is a common intracellular signaling molecule (second messenger) in eukaryotic cells. It is also a regulator of some bacterial operons.
adenylyl cyclase
An enzyme that converts ATP to cyclic AMP in response to an extracellular signal.
inositol triphosphate (IP3)
A second messenger that functions as an intermediate between certain signaling molecules and a subsequent second messenger, Ca2+, by causing a rise in cytoplasmic Ca2+ concentration.
