Chapter 11: Cell Communication Flashcards
What are cell signaling mechanisms an example of?
Evolutionary Relatedness!
What is the connection used in animal cells?
Gap Junctions
What is the connection used in plant cells?
Plasmodesmata
Paracrine Signaling
Signaling cell secretes signaling molecule that only travels a short distance
Synaptic Signaling
secretion of neurotransmitters from a neuron that triggers a response in target cells
Endocrine Signaling
hormones are secreted and travel throughout the body via the bloodstream.
Three Stages of Cellular Signaling
Reception, Transduction, Response
What do “Signal Transduction Pathways” do?
They convert a signal originating outside the cell into a cellular response
What is “reception”?
A signaling molecule bins to a receptor protein, causing it to change shape
What are Ligands?
signaling molecules that bind to another, often larger molecules
what does binding of a ligand do?
causes a change in shape, meaning a change in function too….because structure determines function!
Why is reception specific?
Because cells only respond to signals for which they have a specific receptor for.
Ligands have a high…
degree of specificity
3 main receptors in plasma membranes
1.) G-protein coupled receptor (GPCR)
2.) Receptor Tyrosine Kinase (RTK)
3.) Ligand Gated Ion Channels (LGIC)
When is the GPCR active?
When bound to GTP
What does GTPase do?
hydrolyze GTP to GDP + Pi = inactive
When is the GPCR inactive?
When bound to GDP
What is RTK involved in?
controlling cell division!
What is dimerization?
when ligands bind to 2-receptor monomers, the RTK forms a dimer
What is transduction?
cascades of molecular interactions relay signals from receptor to target molecules in the cell
NOTE***
The original signaling molecule is not passed along, only the information it carries is!
Signal Amplification
benefit of transduction
What molecule carries out protein phosphorylation?
Protein Kinases
What molecule carries out protein de-phosphorylation?
Protein Phosphhotases
What are common second messangers?
Cyclic AMP, Calcium ions
What does the addition of the phosphate do?
Activation!
What are second messangers?
small, non protein molecules that spread rapidly throughout a cell by diffusion or laterally in a membrane
what does cAMP stand for?
cyclic adenosine monophosphate
what does IP3 stand for?
inositol triphosphate
what converts ATP into cAMP?
Adenylyl Cyclase
What converts cAMP back into ATP?
Phosphodiesterase
Where are the calcium ions stored?
Endoplasmic Reticulum
what does DAG stand for?
diacylglycerol
how are IP3 and DAG produced?
they are produced by clevage of specific type of phospholipid called PIP3 in the plasma membrane
What the two main cellular responses?
Cytoplasmic and Nuclear
What do nuclear pathways do?
aid in gene regulation by changing the shape of the proteins made, therefore changing the function
What is the degree of response regulated by? 4 things.
1.) Signal Amplification
2.) Coordination of Response
3.) Signal Efficiency
4.) Termination of Signal
What is signal amplification?
the process by which the activated products can be much greater in number than the preceeding step.
How is signal amplification performed?
Protein Catalysts (Enzymes)
What are the four different signal pathways a signal can take?
1.) Single Response
2.) Two Responses
3.) Cross Talk
4.) Different Response
How do Kinases’ find substrate so quickly?
Scaffolding Proteins
What do scaffolding proteins do?
hold proteins in a pathway together and relay large proteins in order to increase transduction efficiency
What are the 4 inactivation mechanisms?
1.) Reverse Ligand Binding
2.) GTPase hydrolysis of GTP
3.) Dephosphorylation via Phosphotases
4.) cAMP hydrolysis by phosphodiesterase
