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2 cell signaling
June 5
23
Biology
Undergraduate 2
06/05/2015

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Term
What does cell communication underlie?
Definition
life cycle of entire organism
Term
What are the two types of direct contact in a cell
Definition
cell junction (cells touching)
cell-cell recognition (use a receptor to touch cell nearby)
Term
Describe cell communtication without contact (3)
Definition
Cell releases signaling
molecule that is then
detected by receptors
on target cell
 Autocrine – cell
signaling itself
 Paracrine/Synaptic –
nearby cells
 Endocrine – action at a distance,
via circulation
Term
What is autocrine?
Definition
cell signaling itself
Term
What is paracrine/synaptic?
Definition
nearby cells
Term
What is endocrine?
Definition
action at a distance, via circulation
Term
What are the three stages of signaling pathways?
Definition
◦ Reception
◦ Signal transduction
◦ Response
Term
What is reception in signaling pathways?
Definition
signaling molecule
Term
What is signal transduction in signaling pathways?
Definition
Relay molecules in a signal transduction pathway
Term
What is response in signaling pathways?
Definition
activation of cellular response
Term
Why is reception typically done by membrane-spanning proteins?
Definition
Receptor changes shape, develops new activity
Channel
Enzymatic
Docking
Term
Describe the process of reception
Definition
a signaling molecule comes to the channel receptor, the gate opens, the signaling molecule docks and turns into a dimer, it then uses 6 atp to adp to turn fully activated. Then inactive relay proteins approach the dimer and turn active. Once there is a g protein-coupled receptor at the membrane, an inactive g protein is nearby followed with an enzyme. a signaling molecule activates the receptor, using gtp releasing the gdp and then the g protein now being active going the the enzyme, activates it, and causes a cellular response.
Term
What is an exception of reception where it is not done by a membrane-spanning protein?
Definition
 Some signals can cross
membrane in their own
 Intracellular reception
 Steroids
 Nitric oxide (·NO)
Term
What does signal transduction do and describe the process
Definition
Takes message from membrane to site of cellular
response
 Kinase cascade
Second messenger
 Soluble compound that migrates to site of action
Term
How many steps are in the multistep signaling cascades?
Definition
multiple, which allow for signal amplication
Term
What are the two main targets for cellular response?
Definition
◦ Two main targets:
 Gene regulation – production
 Regulation of activity – post-production, Frequently via phosphorylation or Ca2+
Term
What is cell signaling specificity?
Definition
Pattern of signaling differs in different cell types
Term
What are the 5 responses for cell signaling specificity?
Definition
Response 1: Pathway leads to signaling response
Response 2 and 3: Pathway branches leading to two responses
Response 4:cross-talk occurs between two pathways
Response 5:different receptor leads to a different response
Term
What do scaffolds do in cell signaling?
Definition
greater specificity and greater efficiency
Term
Describe a coordinated system
Definition
◦ Calcium pumps move calcium out of cell and into smooth ER against
concentration gradient
◦ A neurotransmitter (signal from a neuron) activates calcium channels in
plasma membrane, causing an influx of extracellular calcium
◦ That calcium binds to and opens calcium channels on the SER, leading to a
massive burst of cytoplasmic calcium
◦ The muscle protein myosin is turned on by the calcium. This pulls the actin
microfilaments toward each other: the muscle contracts
Term
What is apoptosis?
Definition
programmed cell death
Term
where does apoptosis occur?
Definition
in response to cell signaling
Term
Why would you want apoptosis to occur?
Definition
• Kill off damaged or malfunctioning cells
• Remove unwanted cells
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