Chapter 9 Exam 3 Flashcards
what happens to the signaling peptide at low population density
the concentration of the signaling peptide is too low to stimulate DNA uptake by bacteria
what happens in pneumococcal signaling
- the peptide signaling molecule binds to the receptor on the cell surface
- when enough peptide is bound a signal is relayed by a signal transduction to the. nucleic region of the bacterial cell
- genes are turned on that express proteins involved in DNA uptake from the environment
- when the density of bacteria is low the signal falls below its critical threshold and the gene expression is turned off
what is contact dependent signaling
communication through direct physical contact, without a chemical signal that diffuses or circulates through an external medium
what is notch expressing cells
supporting glial cells
what are delta expressing cells
cell develops into a neuron
what signaling molecules bind to cell surface receptors
polar signaling molecules
what signaling molecules bind to intracellular receptors
small non polar signaling molecules
what do kinases do
phosphorylate which turns proteins on
what do phosphates do
dephosphorylate which turns proteins off
what are the 3 kinds of receptor proteins
- GPCRs
- receptor kinases
- ligand gated ion channels
what are the 2 second messengers involved with GPCRs
Ca2+ and cAMP
what do second messengers do
amplify the signal
what happens in GPCR activation
alpha subunit binds GTP and activates adenylyl cyclase, adenylyl cyclase takes ATP and makes cAMP which activates PKA that phosphorylates proteins
how do you reset the cellular response in GPCRs
- alpha subunit is only bound for short amount of time then gets GDP back and rebinds to beta and gamma
- a phosphodiesterase shuts off cAMP to stop activating PKA. when cAMP turns off it goes back to AMP
- phosphates remove phosphate groups from target proteins that were phosphorylated by PKA
what happens in receptor kinases
- ligands bind and bridge 2 kinases which then phosphorylate each other
- they come together and take a phosphate from ATP and phosphorylate each other
- then they phosphorylate other proteins
what is dimerization
when subunits come together into a single protein complex
what happens in RAS signaling
-controls when a cell divides and receives a growth signal
-it’s like a G protein but isn’t one
activated when GDP turns into GTP
what happens in the Map kinase pathway
activated Ras signaling protein activates a kinase which activates another kinase and goes to the nucleus, amplifying the signal as it gets passed
what do receptor kinases do in life
cancer and wound healing. some prevent Ras from convert GTP to GDP causing protein to always be on
what cell signaling issues cause cancer
increased number receptors, overproduction signaling molecule, ras mutations
