Unit 4 - Cell Cell Communication (Signaling) Flashcards
Phosphorylation is a reversible-
post-translational modification that regulates protein function
Intercellular Signals
allow cells to communicate with other cells,
Hormones are
examples of signaling molecules, but not all signaling molecules are hormones
4 Types of Local Cell Signaling
1.Autocrine (signals itself)
2.Paracrine (signal close neighbors)
3.Juxtacrine (signaling molecule is attached between 2)
4.Endocrine (signal diffuse over long distance)
Intracellular Receptors
bind to lipid soluble signals (ex. steroids) that diffuse across the membrane
Cell Surface Receptors
bind to lipid insoluble signals (ex. peptide hormones) that link external environment to cell interior
Ligand
name for intercellular signals
Signal-Transducing Receptors
bind to intercellular signals on surface of cells.
Steps in Signal Transduction Pathway
1.Receptor Activation (bind and activated receptor_
2.Signal Transduction (signal transmitted to inside of cell by pathway)
3.Response (cell responds by activating enzyme or transcription of gene)
4.Termination (response is shut off so new signal can be received)
Ligand-gated Ion Channels
receptors that alter flow of ions across plasma membrane
Signal Amplification
allows cell to be sensitive to small concentrations of signaling molecules
Signal Transduction
conversion of extracellular signal to an intracellular signal
Signal Amplification
occurs when one ligand induces many copies if an intracellular signal, can be accomplished by activation of an enzyme
G protein-coupled receptors (GPCRs)
are huge class of signaling receptors that share a common structure and mechanism of signal transduction,
-associate with G proteins
Lipid anchors
attached hydrocarbons inserted into membrane, associate G proteins with the membrane
Signaling must be turned off so that
the cell doesn’t keep responding to a signal forever
Second Messenger
a small molecule whose concentration temporarily increases or decreases in response to an extracellular signal.
-small=diffuses rapidly and helps relay to other signal proteins
Adenylyl Cyclase
catalyzes conversion of ATP into second messenger cyclic AMP
GTPases
many regulatory proteins controlled by binding to GTP and can hydrolyze GTP to GDP
-almost always, protein active in GTP bound state and inactive in GDP bound state
-GTP hydrolysis energy used by cell to accomplish regulation of cell behavior
