cell communication

Question 1

direct cell communication

Answer 1

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

Question 2

indirect cell communication

Answer 2

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

Question 3

paracrine signaling

Answer 3

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

Question 4

autocrine signaling

Answer 4

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

Question 5

neural signaling

Answer 5

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

Question 6

endocrine

Answer 6

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

Question 7

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

Answer 7

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)

Question 8

receptor specificity

Answer 8

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

Question 9

receptor types

Answer 9

inside membrane and cytoplasm

Question 10

membrane receptors

Answer 10

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

Question 11

cytoplasmic receptors

Answer 11

bind to hydrophobic signals that can cross plasma membrane, steroids

Question 12

3 stages of signaling process in target cell

Answer 12

reception, transductions, response

Question 13

reception

Answer 13

ligand binds to receptor and changes cell function

Question 14

transduction

Answer 14

cell signal being amplified

Question 15

response (2)

Answer 15

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

Question 16

signal transduction pathways

Answer 16

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

Question 17

kinase

Answer 17

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

Question 18

kinase chain and phosphate group

Answer 18

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

Question 19

switches! with kinase & phosphatase

Answer 19

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

Question 20

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

Answer 20

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

Question 21

second messangers function

Answer 21

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

Question 22

3 principal second messangers

Answer 22

cyclic AMP, calcium ions, inositol triphosphate

Question 23

cyclic AMP structre !!!!!

Answer 23

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

Question 24

transmembrane receptors 3

Answer 24

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

Question 25

G-linked protein receptors

Answer 25

linked to relay proteins that bind guanosine di- and triphospahte (GDP, GTP)

Question 26

G-linked protein receptor pathway

Answer 26

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)

Question 27

g-protein linked receptors shape

Answer 27

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,

Question 28

adenylyl cylase

Answer 28

allows synthesis of cyclic AMP

Question 29

activity of cyclic AMP depends on

Answer 29

adenylyl cyclase and G protein activity

Question 30

protein kinase A

Answer 30

top level of transduction pathway, catalyze addition of phosphate group to kinases

Question 31

epinephrine reception

Answer 31

epinephrine binds to G-protein coupled receptor

Question 32

epinephrine transduction

Answer 32

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;

Question 32

epinephrine response

Answer 32

glycogen activates glucose 1-phosphate (10^8) molecules, increases glucose in the blood stream

Question 33

tyrosine kinse recpetors

Answer 33

transmembrane receptors, have 2 components: a kinase and target/relay protein that’s separate from receptor

Question 34

tyrosine kinase receptor ligand binding

Answer 34

has two parts, which dimerize when ligand binds, dimerization activates the kinase part of receptor

Question 35

tyrosine kinse pathway

Answer 35

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

Question 36

insulin receptor

Answer 36

tyrosine kinase receptor, consists of two monomers, each has a beta and alpha (where binding happens) subunit

Question 37

insulin receptor pathway

Answer 37

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

Question 38

glucose transporter molecules (GLUT4)

Answer 38

are activated and inserted in cell membrane due to insulin receptor pathway

Question 39

activation of gene expression by kinase signaling cascades

Answer 39

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)

Question 40

calcium as second messenger

Answer 40

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

Question 41

calmodulin

Answer 41

calcium binds to this, an abundant intracellular protein, which is a kinse that can trigger a calcium dependent protein kinase cascade

Question 42

2 ways of calcium increase intracellularly

Answer 42

facilitated diffusion through ion channels (gates), the release of calcium from intracellular store (smooth ER) by signal transduction cascade that uses inositol trisphosphate (IP3)

Question 43

signal transduction cascade that uses inositol trisphosphate (IP3) activation (2)

Answer 43

either G-protein linked receptors not linked to cAAMP or protein kinase receptors like the insulin receptor

Question 44

phospholipse C function

Answer 44

cleaves PIP2 into two parts, one that stays in membrane and one that goes into cytoplasm (activated by G-protein or tyrosine kinase)

Question 45

PIP2 structure (IP3 made by cleaveage)

Answer 45

ester linkage, fatty acid tail, glycerol, and has. molecule linked to cyclic carbon ring (3 phosphates) and one links to glycerol

Question 46

IP3 function

Answer 46

binds to calcium channel and opens it to allow calcium out, which then goes to calmodulin and cellular response

Question 47

terminate calcium signal

Answer 47

calcium pumps remove calcium from the cytoplasm, use ATP to move Ca2+ againt concentration gradient; pumped into: out of cell, mitochondria, into smooth ER)

Question 48

diversity in cell signaling (3)

Answer 48

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)

Question 49

steroid receptors

Answer 49

use intracellular (cytoplasmic) receptors to control: gene expression, other intracellular signaling pathways (cross talk)