Cellular communication 3

Question 1

What are the three downstream effectors that produce second messengers?

Answer 1

1. adenylyl cyclase
2. phospholipase C
3. Phospholipase A2

Question 2

Adenylyl cyclase stimulates

Answer 2

cAMP

Question 3

Phospholipase C stimulates

Answer 3

IP3 and diacylglycerol

Question 4

Phospholipase A2 stimulates

Answer 4

eicosanoids (20-carbon lipid mediators)

Question 5

cAMP plays a key role in the regulation of

Answer 5

intracellular signal transduction

Question 6

Second messenger effects are

Answer 6

tissue-specific
for example, cAMP may cause a response in one cell type but a completely different response in another

Question 7

The intracellular effects of cAMP are mediated by the enzyme

Answer 7

cAMP-dependent protein kinase, PKA

Question 8

IP3 is a second messenger that leads to

Answer 8

Ca+2 release from intracellular storage sites

Question 9

Many downstream signaling events mediated by Ca+2 are modulated by a

Answer 9

Ca+2 sensing and binding protein, calmodulin (CaM)

Question 10

What activates phospholipase C?

Answer 10

Gq,11 with Ca2+

Question 11

Phospholipase A2 is a Ca2+ dependent enzyme that liberates _____________- from the cell membrane

Answer 11

arachidonic acid

Question 12

What three families of lipid signaling molecules is arachidonic acid the precursor of?

Answer 12

prostaglandins & thromboxanes
leukotrienes
HETEs and EETs

Question 13

Prostanoids, leukotrienes, HETEs, and EETs are collectively called

Answer 13

eicosanoids

Question 14

Phosphates catalyze the removal of

Answer 14

phosphate groups from their substrate

Question 15

Phosphorylation/dephosphorylation of a protein acts as

Answer 15

a molecular switch On/OFF

Question 16

Binding of cAMP to the regulatory subunits causes

Answer 16

dissociation of the catalytic subunits

Question 17

The catalytic subunits of PKA are

Answer 17

serine/threonine (Ser/Thr) kinases

Question 18

Phosphorylation of Ser and The residues by PKA alters

Answer 18

protein function and cellular effects

Question 19

The action of cAMP is terminated by

Answer 19

phosphodiesterases

Question 20

the action of protein kinases is terminated by

Answer 20

protein phosphates

Question 21

DAG and Ca2+ activate

Answer 21

protein kinase C

Question 22

Protein kinase C is involved in many cellular functions including

Answer 22

receptor desensitization
modulating membrane structure events
regulating transcription
mediating immune responses
regulating cell growth
learning and memory

Question 23

The action of DAG is terminated when the molecule is

Answer 23

recycled into new phospholipids

Question 24

IP3 is a second messenger that liberates

Answer 24

Ca2+ from intracellular storage sites

Question 25

Ca2+ signals are terminated by

Answer 25

ATP dependent processes: Ca2+ is pumped out of the cell Ca2+ is returned to the endoplasmic reticulum

Question 26

The action of IP3 is terminated when the molecule is

Answer 26

recycled into new phospholipids

Question 27

Unlike other second messengers, _____________ is NOT synthesized, liberated from a precursor molecule, or activated by enzymes

Answer 27

calcium

Question 28

Calcium's action is terminated by

Answer 28

removal from the cytoplasm by pumps and transporters to terminate its action

Question 29

The active Ca2+/CAM complex has a wide range of downstream targets including

Answer 29

NO synthase Ca2+/CAM-dependent protein kinases (e.g. myosin light-chain kinase) adenylyl cyclase cAMP-specific PDE

Question 30

Which two calcium transporters are found in the plasma membrane?

Answer 30

the sodium-calcium exchanger (NCX) Ca2+ ATPase (pump, PMCA)

Question 31

What enzyme family catalyzes the addition of a phosphate group to a substrate?

Answer 31

kinases catalyze the addition of a phosphate group to their substrates

Question 32

The two types of synapses in the human body are: (select 2) a. chemical b. thermal c. mechanical d. electrical

Answer 32

a. chemical d. electrical

Question 33

___________ play a crucial role in action potentials and other electrical behavior of membranes

Answer 33

Ion channels

Question 34

Ion channels usually have

Answer 34

gated pores

Question 35

An intracellular junction called ____________ helps the nervous system get the right signal to the right place in the body at the right time

Answer 35

the synapse

Question 36

What are the two types of synapses?

Answer 36

electrical and chemical

Question 37

_______________ are the key proteins of signal transduction at chemical synapses

Answer 37

Neurotransmitter receptors

Question 38

Neurotransmitter receptors are transmembrane proteins that are either:

Answer 38

1. ion channels (ionotropic receptors) 2. coupled to heterotrimeric G proteins (metabotropic receptors)

Question 39

Chemical synapses are

Answer 39

polarized (primarily one-way communication)

Question 40

Chemical synapses are comprised of the

Answer 40

presynaptic terminal synaptic cleft postsynaptic membrane of the target cell

Question 41

Ion channels increase the permeability of the membrane to

Answer 41

ions

Question 42

Ion channels exhibit

Answer 42

ion selectivity

Question 43

Ion channels usually have

Answer 43

gated pores

Question 44

Important signals that open and close the gated pores are:

Answer 44

membrane voltage--> voltage-gated ion channels chemicals-->ligand gated ion channels pressure--> mechanically gated ion channels

Question 45

Chemical signals are designed to convert _________________ into a ___________________- through the release of neurotransmitters

Answer 45

an electrical signal into a chemical signal

Question 46

Chemical synapses communicate messages in

Answer 46

one direction from the presynaptic membrane to the postsynaptic membrane

Question 47

Electrical synapses are designed to allow ____________ and ____________- messages to flow directly from

Answer 47

electrical & chemical messages to flow directly from one cell to another in a bi-directional fashion

Question 48

At electrical synapses, cells are connected by

Answer 48

gap junctions