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BIO 104 > Chapter 5/Cell Signaling in Physiology > Flashcards

Chapter 5/Cell Signaling in Physiology Flashcards

1
Q

Chemical messengers bind to

A

receptor

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2
Q

Water-soluble messengers bind to receptors
located at the

A

plasma membrane

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3
Q

Lipid-soluble messengers bind to

A

intracellular
receptors

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4
Q

cells express different receptors

A

Specificity

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5
Q

strength of ligand-receptor binding

A

Affinity

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6
Q

Different cells can have different responses to same
ligand

A

Specificity: cells express different receptors.

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7
Q

High affinity will bind at lower concentrations of
messenger

A

Affinity: strength of ligand-receptor binding

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8
Q

the fraction of total binding sites
that are occupied

A

Saturation

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9
Q

presence of multiple ligands able
to bind the same binding site

A

Competition

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10
Q

blocks the action of a chemical
messenger

A

Antagonists

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11
Q

activates receptors and triggers the cell’s
response

A

Agonist

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12
Q

receptors are removed
(internalized) in response to intense exposure to chemical messengers.

A

Down-regulation

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13
Q

number of receptors is
increased in response to low concentrations of
chemical messengers

A

Up-regulation

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14
Q

Up-regulation & down-regulation

A

Receptor Regulation

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15
Q

Can diffuse through the plasma membrane.
– Have intracellular receptors.
– Signal-receptor complexes bind directly to DNA
and alter gene expression.
– Slower response, but sustained response

A

Lipid-soluble messengers

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16
Q

A broad range of receptors.
– Activate intracellular signaling cascades
– Can activate mediators that affect DNA
expression
– Faster response but less sustained.
– Involve first messengers and second messengers

A

Membrane-bound receptors

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17
Q

Lipid-soluble messengers,
Membrane-bound receptors

A

Signal Transduction Pathways

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18
Q

Activation of receptor results in open ion
channel.
* Opening of ligand gated ion channels increase
net diffusion of ions specific to channel.
* Often results in a change in the membrane
potential.
* Ex: Na+, K+, Ca2+

A

Ligand-Gated Ion Channels

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19
Q

Some receptors have intrinsic

A

enzyme activity

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20
Q

Most are protein kinases that phosphorylate
the amino acid tyrosine

A

Receptor tyrosine kinase

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21
Q

transferring a phosphate
group from ATP

A

Phosphorylation

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22
Q

Binding of messenger to
receptor activates
enzymatic portion of
receptor.
* This autophosphorylates
the receptor’s tyrosine
groups
* Docking proteins bind to
phosphorylated tyrosine
groups.
* Activate cell’s response

A

Events for receptors with tyrosine kinase activity

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23
Q

These receptors do not have intrinsic kinase activity

A

Cytoplasmic Kinases

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24
Q

Binding of ligand causes conformational
change in receptor that leads to activation of

A

JAK kinase

25
Q

-Family of 4 kinases, target different transcription
factors.
–Results in synthesis of new proteins.

A

Cytoplasmic Kinases

26
Q

Receptor with inactive protein complex bound to it.

A

G Proteins

27
Q

3 subunits: alpha, beta, gamma.
– Alpha subunit can bind GDP and GTP.
– Beta and gamma subunits anchor alpha subunit to
the membrane

A

G-Proteins

28
Q

Binding of ligand to receptor changes
conformation of the receptor.
– Activated receptor increases the affinity of alpha subunit for GTP
– Alpha subunit binds GTP and dissociates from the
beta and gamma subunits.
– Alpha subunit binds to effector protein in plasma
membrane.

A

Steps

29
Q

G protein serves as a BLANK coupling a
receptor to an ion channel or to an enzyme

A

SWITCH

30
Q

Can be stimulatory or inhibitory

A

G Protein-Coupled Receptors

31
Q

Most numerous type of receptor family, large
variety of signaling pathways

A

G Protein-Coupled Receptors

32
Q

Adenylyl Cyclase

A

Second Messengers

33
Q

Activated by stimulatory G proteins
– Catalyzes the conversion of ATP to cyclic AMP
(cAMP)
– cAMP acts as a second messenger

A

Adenylyl Cyclase

34
Q

cAMP action

A

Second Messengers

35
Q

cAMP action is terminated by cAMP BLANK

A

phosphodiesterase

36
Q

-Breaks down cAMP
– Inhibition of cAMP phosphodiesterase prolongs
actions of cAMP

A

Second Messengers

37
Q

cAMP binds to
-PKA phosphorylates downstream targets

A

cAMP-dependent protein
kinase (PKA

38
Q

Some G proteins inhibit
Results in less generation of cAMP

A

adenylyl cyclase

39
Q

activated by Gq,
catalyzes breakdown of a phospholipid (PIP2)
-second messengers

A

Phospholipase C (PLC)

40
Q
  • Diacylglycerol (DAG)
    – Inositol Triphosphate (IP3)
    – Both function as second messenger
A

Phospholipase C (PLC

41
Q
A
42
Q

DAG activates

A

protein kinase C

43
Q

IP3 binds to ligand gated Ca2+ channels in

A

ER

44
Q

Ca2+ as

A

Secondary Messenger

45
Q

Ca2+ can be increased or decreased to elicit a
cellular response

A

action potential

46
Q

Ca2+ is maintained at BLANK concentration in the
cell

A

Low

47
Q

Electrochemical gradient favors diffusion into the
cytosol via

A

Ca2+ channels

48
Q

Cell can be altered by influencing active
transport systems of

A

Ca2+

49
Q

– Calmodulin
– Troponin
– Kinases

A

Ca2+ also acts by binding proteins and
activating them

50
Q

Ca2+ as

A

Secondary Messenger

51
Q

Ca2+ also acts by

A

binding proteins and
activating them

52
Q

Signal transduction pathways are eventually

A

shut off

53
Q

-Cessation of receptor activation
-Decrease in concentration of first messenger

A

Cessation of Activity

54
Q

-Receptor become chemically altered
– Phosphorylation of receptor prevents further G
protein binding to the receptor
– Plasma membrane receptors may be removed

A

Receptors can be inactivated in 3 ways

55
Q

Signal pathways do not exist in isolation, they
occur simultaneously.
* Many first messengers may simultaneously
influence a cell.
* “Cross-talk” can occur at one or more levels
among signal transduction pathways.

A

Interactions of Signal Transduction Pathways

56
Q

Signal pathways do not exist in isolation, they
occur BLANK

A

simultaneously

57
Q

Many BLANK messengers may simultaneously
influence a cell.

A

first

58
Q

can occur at one or more levels among signal transduction pathways

A

Cross-talk

BIO 104 (13 decks)

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