Module 4: Cell Signaling and Cell to Cell Communication Flashcards
Bacteria (prokaryotes) can talk to each other through the diffusion of certain chemicals; one example of this is
Quorum sensing
Disease-causing bacteria will not produce toxins until they sense an adequate population of themselves. This increases _____
This increase the probability to survive host defenses, such as antibodies
Microbes in a biofilm can ______ with each other
Communicate
Interceller
Between cells, often based on ligands and receptor
Intracellular
Within cells, based on nuclear and cytoplasmic signal transduction
Small hydrophobic ligands
Usually transported by carrier proteins
Hydrophilic ligands
Usually large, will not cross the plasma membrane; generally bind to extracellular receptors
Internal receptors
Generally respond to hydrophobic ligands that can cross the plasma membrane
Many internal receptors bind directly to DNA after binding to the ligand. Can directly influence gene expression in this way
Cell-surface receptors
Integral proteins that bind to external ligands
Interact with other proteins on the membrane and participate in signal transduction
Extracellular signal is converted to an intracellular signal
How many types of cell-surface receptors?
3
Ion channel-linked receptors
Binding of a ligand causes a conformational change, allowing the passage of the ion/molecule
G-protein-linked receptors
When signal molecule is entered, GTP is hydrolyzed to GDP, leading to a dissociation of the G protein subunits that mediate downstream cell signals
(activate when bound to GTP, inactive when bound to GDP)
G-protein-coupled receptors result in
Short term response
Enzyme-linked receptors
When signaling molecules bind to the receptors, they dimerize. Tyrosine residues phosphorylate and a cellular response is released inside the cell
Kinase receptors usually operate in
Pairs
Kinase receptors result in
Long term responses
Intracrine signaling
The signal is any hormone or ligand acting inside the cell, receptor is also inside the cell
Autocrine signaling
Signal is produced inside cell then sent outside cell, where it binds with a receptor on that same cell
Gap junctions
Allows signaling between adjacent cells. Only small molecules can pass through (like ions), large molecules like DNA and proteins can’t
Juxtracrine signaling
Targets adjacent cells by direct contact
Endocrine signaling
Signals from distant cells. Slower response but have longer-lasting effect
Pheromones
Chemicals capable of acting like hormones outside the body of the secreting individual
Cellular communication essentials
Signaling cell, signaling molecule, receptor protein, responding cell
Signaling involves
Receptor activation, signal transduction, response, and response termination
Phosphorylation is done by
Kinases
Phosphorylation is
The addition of a phosphate group to a molecule such as a protein
The overall effect of G-protein coupled receptor activation
Signal amplification
cAMP and Ca+ are
Second messengers
Second messengers serve as
signal amplification
Effect of phosphorylation on proteins:
causes conformation changes to the proteins
