cell communication Flashcards

(51 cards)

1
Q

direct cell communication

A

direct exchange of materials between the cytoplasm (gap junctions, plasmodesmata) (touching!); direct interaction of cell surface molecules (touching!)

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2
Q

indirect cell communication

A

indirect communication between two non-contacting cells using a signal released from one cell that affects the function of a second; different types of signaling systems that are based on the distance that separates the 2 cell types or nature of signal

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3
Q

paracrine signaling

A

the release of a chemical signal from one cell that is detected by and alters the function of a CLOSELY located cells

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4
Q

autocrine signaling

A

the release of a chemical signal from one cell that is detected by and alters the function of the SAME CELL, specialized signaling mechanism that allows the signaling cell to monitor the amount of signal that is being released

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5
Q

neural signaling

A

synaptic signaling, over short distance between neurons, synapse between cells, neurotransmitters diffuse across synapse

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6
Q

endocrine

A

long distance (hormonal) signaling, signaling aka hormone put into blood stream

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7
Q

whaat types of molecules can act as signals? (4)

A

amino acids (glutamic acid excitatory neurotransmitter), amino acid derivatives (GABA glutamic acid, major inhibitory neurotransmitter, Epinephrine tyrosine, hormone that increases blood glucose), steroids (estrogen, glucocorticoids), peptides and proteins (insulin, glucaogon), gases (nitric oxide, vasodilator)

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8
Q

receptor specificity

A

signals (ligands) cannot alter cell function until binded to receptor SPECIFIC

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9
Q

receptor types

A

inside membrane and cytoplasm

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10
Q

membrane receptors

A

interact with hydrophilic signals that cannot cross the plasma membrane, amino acids, their derivatives, peptides

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11
Q

cytoplasmic receptors

A

bind to hydrophobic signals that can cross plasma membrane, steroids

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12
Q

3 stages of signaling process in target cell

A

reception, transductions, response

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13
Q

reception

A

ligand binds to receptor and changes cell function

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14
Q

transduction

A

cell signal being amplified

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15
Q

response (2)

A

activation of cellular responses: alteration of enzyme function or alteration of gene expression

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16
Q

signal transduction pathways

A

cascades of intracellular events, triggered by the binding of ligand to specific receptor, ligand binding activates series of KINASE enzymes

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17
Q

kinase

A

enzyme that add a phosphate group onto another molecule usually a protein and often another enzymes

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18
Q

kinase chain and phosphate group

A

the phosphate group will change the shape of the protein and alter its function, leads to enzyme activation, phosphatase reduce enzymatic activity

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19
Q

switches! with kinase & phosphatase

A

phosphate groups are switches activated by kinases, phosphate groups are removed/turned off by phosphatase

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20
Q

3 advantages to cascade of signal / structure of cell signaling pathway

A

signal is amplified, allows one signal to diverge and control a whole range of cellular processes, allows other signals to control cascade

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21
Q

second messangers function

A

act to trigger the transduction cascade, intracellular concentrations are controlled by receptor activation, function as intermediaries between the receptor and cascade

22
Q

3 principal second messangers

A

cyclic AMP, calcium ions, inositol triphosphate

23
Q

cyclic AMP structre !!!!!

A

adenosine triphosphate and ribose, has ATP, cyclic through pyrophosphate (cycle) and phosphodiesterase (decycle)

24
Q

transmembrane receptors 3

A

G-linked receptors (epinephrine receptor), tyrosine-kinase receptor (insulin), ligand gated receptor, (calcium channels)

25
G-linked protein receptors
linked to relay proteins that bind guanosine di- and triphospahte (GDP, GTP)
26
G-linked protein receptor pathway
ligand binds, G-protein can now bind to receptor, GDP replaced by GTP, allows the G-protein to move along membrane to adjacent enzyme to inhibit or activate it, GTP on G-protein is the hydrolyzed back to GDP and G-protein is deactivated (ligand dissociates)
27
g-protein linked receptors shape
lots of alpha helices, cholesterol, molecule mimicking ligands, signal binding site has to have ligand inserted correctly, 7 alpha helices (hydrophobic amino acids) in structure, N-terminus outside, C-terminus on inside of cell,
28
adenylyl cylase
allows synthesis of cyclic AMP
29
activity of cyclic AMP depends on
adenylyl cyclase and G protein activity
30
protein kinase A
top level of transduction pathway, catalyze addition of phosphate group to kinases
31
epinephrine reception
epinephrine binds to G-protein coupled receptor
32
epinephrine transduction
10^2 active G protein, 10^2 adenylyl cyclase, 10^4 cyclic AMP, active protein kinase A 10^4, phosphorylase kinase 10^5, glycogen phosphorylase 10^6 (active molecules increase and amplify;
32
epinephrine response
glycogen activates glucose 1-phosphate (10^8) molecules, increases glucose in the blood stream
33
tyrosine kinse recpetors
transmembrane receptors, have 2 components: a kinase and target/relay protein that's separate from receptor
34
tyrosine kinase receptor ligand binding
has two parts, which dimerize when ligand binds, dimerization activates the kinase part of receptor
35
tyrosine kinse pathway
after ligand binds and kinase is activated, kinase moves phosphate group from ATP to a specific amino acid (tyrosine, serine, or threonine) located iwthin the cytoplasmic part of the receptors polypeptide chain, protein kinase receptor (auto)phosphorylates itself, which then activate rely proteins by phosphorylation
36
insulin receptor
tyrosine kinase receptor, consists of two monomers, each has a beta and alpha (where binding happens) subunit
37
insulin receptor pathway
two molecules of insulin bind to receptor, when insulin binds to alpha subunit, receptor dimerizes, activates protein kinase in the beta subunit of receptor, autophosphorylates, insulin receptors target and phosphorylate other cytoplasmic proteins call insulin response substrates, (LOWERS GLUCOSE), control insertion of glucose transporters into the membrane
38
glucose transporter molecules (GLUT4)
are activated and inserted in cell membrane due to insulin receptor pathway
39
activation of gene expression by kinase signaling cascades
response activates or deactivates transcription factor on DNA and genes in nucleus, (by phosphorylation cascade in cytoplasm to nucleus, a kinase moves into nucleus and activate transcription factor)
40
calcium as second messenger
can activate a larger number of different signaling and cellular proteins, concentration of calcium is carefully controlled inside cell (can be very less than outside the cell), abrupt increases cause series of cellular events
41
calmodulin
calcium binds to this, an abundant intracellular protein, which is a kinse that can trigger a calcium dependent protein kinase cascade
42
2 ways of calcium increase intracellularly
facilitated diffusion through ion channels (gates), the release of calcium from intracellular store (smooth ER) by signal transduction cascade that uses inositol trisphosphate (IP3)
43
signal transduction cascade that uses inositol trisphosphate (IP3) activation (2)
either G-protein linked receptors not linked to cAAMP or protein kinase receptors like the insulin receptor
44
phospholipse C function
cleaves PIP2 into two parts, one that stays in membrane and one that goes into cytoplasm (activated by G-protein or tyrosine kinase)
45
PIP2 structure (IP3 made by cleaveage)
ester linkage, fatty acid tail, glycerol, and has. molecule linked to cyclic carbon ring (3 phosphates) and one links to glycerol
46
IP3 function
binds to calcium channel and opens it to allow calcium out, which then goes to calmodulin and cellular response
47
terminate calcium signal
calcium pumps remove calcium from the cytoplasm, use ATP to move Ca2+ againt concentration gradient; pumped into: out of cell, mitochondria, into smooth ER)
48
diversity in cell signaling (3)
pathway leads to signal response, pathway branches, leading to two responses, cross-talking (interactions between different cascades) occurs between two pathways (IP3 example); different receptor leads to a different response becaus target cells have different responses (serotonin receptors)
49
steroid receptors
use intracellular (cytoplasmic) receptors to control: gene expression, other intracellular signaling pathways (cross talk)
50