CH 16

Question 1

Endocrine Signaling

Answer 1

Hormones produced in endocrine glands are secreted into the bloodstream and are distributed
widely throughout the body.

Question 2

Paracrine Signaling

Answer 2

Paracrine
signals (local mediators) are released by
cells into the extracellular fluid in their
neighborhood and act locally.

Question 3

Neuronal signaling

Answer 3

Neuronal
signals are transmitted electrically along a
nerve cell axon. When this electrical signal
reaches the nerve terminal, it causes the
release of neurotransmitters onto adjacent
target cells.

Question 4

Contact dependent signaling

Answer 4

In contact-dependent
signaling, a cell-surface-bound signal
molecule binds to a receptor protein on an
adjacent cell

Question 5

Intra vs Extracellular signaling molecules

Answer 5

Intracellular - Small hydrophobic molecules that pass through membrane

Extracellular - Large hydrophilic molecules, bind outside membrane

Question 6

Are signaling molecules limited to one response?

Answer 6

No, ACETYLCHOLINE can increase salivation and also slow down heart rate

Question 7

Quick responses

Answer 7

cell movement,
secretion, or metabolism

Question 8

Slow responses

Answer 8

cell differentiation
increased cell growth/division
gene expression
synthesis of new proteins

Question 9

Extracellular pathway…

Answer 9

Signal molecule triggers intracellular signaling molecules that eventually trigger effector proteins

Question 10

5 functions of intracellular signaling molecules

Answer 10

Relay, Amplify, Integrate, Feedback, Distribution

Question 11

Relay Function

Answer 11

Propagates signal to further signaling molecules

Question 12

Amplify Function

Answer 12

Makes signal larger and relayed heavier

Question 13

Integrate Function

Answer 13

Process of taking in multiple signals to initiate a resonse

Question 14

Feedback Function

Answer 14

modulate the response to slow down/speed up
preceding signal transduction

Question 15

Distribute Function

Answer 15

activating multiple effector proteins to create a
complex response

Question 16

Molecular switches examples

Answer 16

ATP and GTP,

ATP: donates phosphate to turn on/off

GTP- GDP gains phosphate, GTP then binds turning on or off

Question 17

GTPase

Answer 17

enzyme, on when GTP binds, then hydrolyzes GTP to GDP, GDP triggers off.

Question 18

G-Protein-coupled receptor structure

Answer 18

-All the same
-7 alpha helices

Question 19

Stimulation of GPCRs activates…

Answer 19

G-Protein subunit on cytosolic side

Question 20

Activation of GPCR does what to alpha subunit of G protein? (start to finish)

Answer 20

lose affinity for GDP, swap for GTP

The alpha subunit then activates or deactivates target protein, then hydrolyzes itself to GDP and returns to inactive state

Question 21

Where are the G protein subunits in a cell?

Answer 21

aby are together in inactive state tethered by two short lipids tails to cytosolic side of membrane.

Question 22

what can the activated b-y subcomplex do?

Answer 22

interact with target proteins on the plasma membrane.

Question 23

Cholera toxin - how does it work

Answer 23

Modifies alpha subunit, makes it so that it cannot hydrolyze ATP and causes continous stimulation of adenyl cyclase resulting in outflow of Cl- and water into gut. (diarrhea)

Question 24

Whooping Cough ( Pertussis Toxin )
- how does it work

Answer 24

alters alpha subunit, inhibits adenyl cyclase locking in inactive state causing cough.

Question 25

G proteins can regulate what type of channels

Answer 25

Ion-gated channels

Question 26

what can the b-y subunit activate?

Answer 26

K+ channels, opens channels allowing K+ to flow out, makes membrane potential more negative, slower heart rate, harder depolarization

Question 27

what is the most frequent target enzyme for G proteins

Answer 27

Adenyl Cyclase

Question 28

What does Adenyl Cyclase do

Answer 28

produce cAMP secondary messengers

Question 29

Cyclic AMP pathway function

Answer 29

activate enzymes and turn on genes

Question 30

Cyclic AMP pathway

Answer 30

Alpha subunit switches on Adenyl Cyclase Adenyl Cyclase increases cAMP from ATP cAMP phosophodiesterase converts cAMP to AMP

Question 31

Protein Kinase A (PKA) activation

Answer 31

normally inactive, activated by cAMP phosphorylates and activates an enzyme called phosphorylase kinase

Question 32

phosphorylase kinase

Answer 32

phosphorylates and thereby activates glycogen phosphorylase, the enzyme that breaks down glycogen also phosphorylates and thereby inactivates glycogen synthethase

Question 33

High levels of intracellular cAMP can activate...

Answer 33

Gene transcription

Question 34

Inositol phospholipid pathway

Answer 34

triggers rise of intracellular Ca+ GPCR can active phospholipase C Phospholipase C propagates signal by cleaving inositol phospholipid in plasma membrane Cleavage causes formation of secondary messengers ( DAG & IP3 )

Question 35

IP3 function

Answer 35

Binds Ca2+ channels in Endoplasmic Reticulum and causes Ca2+ to rush out and signal other proteins

Question 36

DAG function

Answer 36

membrane bound lipid Once separated, activates PKC and Ca2+ to phosphorylize other intracellular proteins.

Question 37

Largest class of enzyme coupled receptors

Answer 37

RTKs

Question 38

RTK pathway

Answer 38

signal molecule binds to RTK Two RTKs bind to form dimer intracellular kinase domains phosphorylate each other on tyrosine residues Activates RAS GEF RAS turns on

Question 39

RTK function

Answer 39

most activate the GTPase RAS

Question 40

Ras structure

Answer 40

GTP binding protein that is bound by lipid tail to cytosolic face of membrane resembles alpha subunit active w GTP, inactive w GDP

Question 41

RAS GEF vs RAS GAP

Answer 41

GEF - encourages swap of GDP to GTP GAP - encourages swap of GTP to GDP

Question 42

What does RAS activate

Answer 42

MAP-Kinase signaling molecule

Question 43

MAP kinase function

Answer 43

makes changes in Gene expression and protein activity

Question 44

PI-3-kinase RTK pathway

Answer 44

causes cell growth and division

Question 44

Akt function

Answer 44

promotes cell survival via signaling Tor (simulates growth)