chapter 11 Flashcards
Describe the difference between paracrine, synaptic, and endocrine signaling.
paracrine signaling: is local, affecting nearby cells
synaptic signaling: occurs between neurons in the nervous system
endocrine signaling: involves hormones traveling through the bloodstream to reach target cells
Describe the three stages of cell signaling.
reception: signal molecule binds to a receptor on the target cell
transduction: signal is converted into the form that the cell can understand
response: cell carriers out a specific response to the signal
what is a protein phosphatase?
-An enzyme that removes phosphate groups from proteins, often functioning to reverse the effect of a protein kinase.
is a protein phosphatase generally an activating enzyme or an inactivating enzyme?
-it could do both
What’s the difference between a cell surface and intracellular receptor? what type of signaling molecule is used for each receptor type?
cell surface receptors are on the cell membrane and interact with large, water-loving molecules
interacellular receptors are inside the cell and interact with the small, water-fearing molecules
what is a second messenger?
-Second messengers are intracellular signaling molecules released by the cell in response to exposure to extracellular signaling molecules—the first messengers.
how is cAMP produced?
-It is synthesized from adenosine triphosphate (ATP) by enzymes (g-proteins) that are attached to metabotropic receptors and become released when the receptor is activated.
outline how cAMP functions as a second messenger for a GPCR?
-cAMP is regulated by the activation of G protein-coupled receptors (GPCRs) and mediates numerous biological responses.
outline the steps in the activation of an intracellular receptor leading to a cellular response
- Reception: A cell detects a signaling molecule from the outside of the cell.
- Transduction: When the signaling molecule binds the receptor it changes the receptor protein in some way.
- Response: Finally, the signal triggers a specific cellular response.
Outline the steps in the activation of a GPCR leading to a cellular response
step 1: a specific signaling molecule, such as a hormone or neurotransmitter, binds to the GPCR on the cell surface
step 2: this binding triggers a conformational change in the GPCR, causing it to activate and undergo a structural rearrangement
step 3: the activated GPCR interacts with the G protein, which is a protein complex xomposed with three subunits( alpha, beta, gamma). this interaction causes the G protein to exchange GDP for GTP, activating the G protein
step 4: the activated G protein dissociates from the GPCR and interacts with an effectors protein, which can be an enzyme or an ion channel. the G protein transfers the signal to the effectors, leading to the activation or inhibitor of the effectors functions
step 5: theactivated signaling proteins trasmit the signal downstream, leading to the activation of multiple signaling pathways. these pathways can involve the activation of protein kinases, the production of second messengers or the modulation of gene expression
Outline the steps in the activation of a RTK leading to a cellular response.
step 1: a specific signaling molecule, called a ligand, binds to the extracellular domain of the RTK
step 2: the binding of ligans causes two RTL molecules to come together and form a dinner. this dimerization brings the intercellular domains of the RTK close to each other
step 3: the dimerized RTK undergo autophosphorylation, where they add phosphate groups to specific tyrosine residues on each others intercellular domains. this phosphorylation step activates the RTK
step 4: the phosphorylated RTK acts as a docking site for various signaling proteins, such as adaptar proteins and enzymes. these proteins bind to the phosphorylated tyrosine residues and become activated or initiate downstream signaling cascade
