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BIOL 3510 - Cell Biology Lecture > Chapter 16 - Part I - Cell Signaling > Flashcards

Chapter 16 - Part I - Cell Signaling Flashcards

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1
Q

Signaling cells produce _____ molecules.

A

signaling

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2
Q

Target cells detect the signal using a ____.

A

receptor protein

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3
Q

What term describes the extra cellular signal that is converted to an intracellular signal?

A

signal transduction

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4
Q

Regardless of the nature of the signal, the target cell responds by means of a specific protein called a ______, which binds the signaling molecule then initiates a response in the target cell.

A

receptor

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5
Q

Cells are typically exposed to many different types of signaling molecules. Cells are not responding all signals. Your cells respond to some signals but ignore others. What determines whether a cell responds to a signaling molecule?

A

Presence or absence of…. 1- Receptor 2- Intracellular signaling molecules and intracellular effector proteins 3- Combinations of signals give different responses

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6
Q

What are the 4 basic types of cell signaling?

A

Endocrine, paracrine, neuronal, contact-dependent

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7
Q

Which cell signaling is carries through the blood stream?

A

endocrine

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8
Q

Which cell signaling does not require the release of a secreted molecule such as a hormone and this method is used for very localized signaling event?

A

contact-dependent

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9
Q

Which cell signaling cell type is physically contacting each other?

A

contact-dependent

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10
Q

The cell signal type that remains in the neighborhood of the secreted cell type?

A

paracrine

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11
Q

The cell signal type that involves a local mediator?

A

paracrine

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12
Q

Which signal cell type involves the conversion of electrical impulses just like action potential into a chemical signals?

A

neuronal

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13
Q

Which signal cell type involves a neurotransmitter?

A

neoronal

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14
Q

Which cell type involves a hormone?

A

endocrine

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15
Q

Animal cell use ______ signal molecules to communicate with one another in various ways.

A

extracellular

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16
Q

Hormones are secreted by ____ cells into the bloodstream and are distributed widely throughout the body?

A

endocrine

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17
Q

Which cell signaling type involves long-range signaling?

A

endocrine

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18
Q

What type of signals diffuse in the extracellular fluid and as as local mediators on **on nearby cells**?

A

paracrine

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19
Q

In paracrine cell signaling, if the secreting cell itself responds, that is called ______ signaling.

A

autocrine

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20
Q

Many of the signal molecules that regulate inflammation at the site of an infection is ____ cell signaling.

A

paracrine

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21
Q

Cell signaling that involves neighborhood or self-signaling is ____.

A

paracrine.

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22
Q

What cell signaling involves a signal (neurotransmitter) that is delivered to a specific target cell at the synapse?

A

synaptic

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23
Q

What cell signaling involves direct signaling?

A

synaptic

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24
Q

Which cell signaling type involves the signaling molecule that is not released by the signaling cell?

A

contact-dependent

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25
Q

Which cell signaling type is important for the embryonic development and immune response and cell-to-cell communication via direct contact without the diffusion of signaling molecule?

A

contact-dependent

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26
Q

Many of the same types of signal molecules are used for endocrine, paracrine, and neuronal signaling. The crucial difference lies in the ______ and _____ with which the signals are delivered to their targets.

A

speed; selectivity

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27
Q

Rank the following types of cell signaling from 1 to 4, with 1 representing the type of signaling in which the signal molecule travels the least distance, and 4 the type of signaling in which the signal molecule travels the largest distance. ___ paracrine signaling ___ contact-dependent signaling ___ neuronal signaling ___ endocrine signaling

A

3, 1, 2, 4

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28
Q

Rank the following types of cell signaling from 1 to 4, with 1 representing the type of signaling in which the signal molecule travels the largest distance, and 4 the type of signaling in which the signal molecule travels the least distance. ___ paracrine signaling ___ contact-dependent signaling ___ neuronal signaling ___ endocrine signaling

A

2, 4, 3, 1

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29
Q

Extracellular signal molecules bind either to ____ receptors or to ____ receptors.

A

cell-surface; intracellular

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30
Q

Signal molecules can be protein, peptide, amino acid, steroid, nucleotides, ions, or even dissolved gases. True or False?

A

True

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31
Q

Cell-surface receptors and binding occur inside the cell. True or false?

A

False. The extracellular signal molecule is huge and hydrophilic and can not enter the cell.

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32
Q

Cell-surface receptors and binding occur outside the cell. True or false?

A

True

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33
Q

Intracellular receptors involve large, hydrophilic molecules and an intracellular receptor. True or false?

A

False. It involves a small, hydrophobic signal molecule.

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34
Q

Intracellular receptors involve small, hydrophobic molecules and an intracellular receptor. True or false?

A

True

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35
Q

All cell types respond to acetylcholine the same. True or false?

A

False. Different cell types respond to acetylcholine differently.

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36
Q

Without signals, most cells undergo a form of cell suicide known as ___.

A

apoptosis

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37
Q

Cell responses that include molecular events like the release of vesicles, and firing action potentials are very (rapid or slow?)

A

rapid

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38
Q

A fast cell response involves a change in ___ activity.

A

protein

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39
Q

A slow cell response involves a change in _____, _____ and _____.

A

gene expression; cell growth; division

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40
Q

Altered protein synthesis is a (fast or slow?) cell response.

A

slow

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41
Q

Altered protein function is a (fast or slow?) cell response.

A

fast

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42
Q

Why does gene expression take longer?

A

The gene will need to be transcribed then mRNA will need to be translated and the protein needs to be accumulated to high enough levels to initiate changes. So that takes time.

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43
Q

Extracellular signaling molecules can bind ____ receptors or ___ receptors.

A

cell-surface; intracellular

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44
Q

The location of a receptor depends on whether the signaling molecule is ___ or ____.

A

polar; nonpolar

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45
Q

Cell-surface receptors are also called _____ receptors.

A

transmembrane

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46
Q

Name two types of hormones that cross the plasma membrane and bind intracellularly.

A

steroid and thyroid hormones

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47
Q

___ and ___ hormones are hydrophobic molecules that bind nuclear receptors promoting transcription.

A

steroid; thyroid

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48
Q

What type of hormones are cortisol, estradiol and testosterone?

A

steroid

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49
Q

What type of hormone is thyroxine?

A

thyroid

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50
Q

Which steroid hormone is produced in the adrenal glands in response to stress?

A

cortisol

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51
Q

Cortisol is nonpolar and can easily cross the membrane. Where are the receptors located?

A

cytosol

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52
Q

For nonpolar signaling molcules, the receptors are located on the surface on the cell. True or false?

A

False. The receptors are NOT located on the surface of the cell.

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53
Q

Steroids are (hydrophilic or hydrophobic?)

A

hydrophobic

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54
Q

Some gases diffuse across the plasma membrane and bind intracellularly. Nearby nerve endings release ____ triggering the production of ___ acid.

A

acetylcholine; nitric

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55
Q

DIffusion of ___ from the endothelial cells promotes relaxation of adjoining smooth muscle cells.

A

nitric acid

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56
Q

Diffusion of nitric oxide from the endothelial cells to the smooth muscle promotes ____ of smooth muscle cell.

A

relaxation

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57
Q

____ triggers smooth muscle relaxation in a blood-vessel wall.

A

nitric oxide

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58
Q

____ has been used for almost 100 years to treat patients with angina- pain caused by inadequate blood flow to the heart muscle.

A

Nitroglycerine

59
Q

In the body, ___ is converted to __, which rapidly relaxes blood vessels.

A

nitroglycerine; NO

60
Q

____ reduces the workload on the heart and decreases the muscle’s need for oxygen-rich blood.

A

Nitric acid (NO)

61
Q

_____ within an intracellular signaling pathway can **adjust the response** to an extracellular signal.

A

Feedback regulation

62
Q

Intracellular signaling proteins are molecular _____.

A

switches

63
Q

_____ turn on the signaling by protein phosphorylation.

A

Protein kinase

64
Q

_____ turn off the signaling by protein phosphorylation.

A

protein phosphatase

65
Q

_____ turn on the signaling by GTP-binding proteins.

A

GTP binding

66
Q

_____ turn off the signaling by GTP-binding proteins.

A

GTP hydrolysis

67
Q

What are the 3 types of extracellular receptors?

A

1- Ion-channel-coupled receptors;

2-G-protein-coupled receptors (GPCR);

3- Enzyme-coupled receptor

68
Q

What type of receptors are signal binding that opens the channel which allows ions to cross the plasma membrane and hence, **alters the membrane potential**?

A

1- Ion-channel-coupled receptors;

69
Q

Which extracellular receptor has seven transmembrane domains?

A

G-protein-coupled receptors

70
Q

Signal binding to a GPCR ___ a G-protein. G-proteins activate ___ channels for enzymes.

A

activates; downstream

71
Q

Which extracellular receptor involves a trimer?

A

GPCR

72
Q

After signal binding, these enzyme-coupled receptor act as ___ or activate other ___.

A

enzyme enzymes

73
Q

Which extracellular receptors were discovered for their role in responding to growth factors in animal cells?

A

enzyme-coupled receptor

74
Q

The number of different types of receptors is ___ than the number of extracellular signals that act on them.

A

greater

75
Q

Foreign substances like nicotine, morphine, and menthol exert their initial effects by ____.

A

interact with cell-surface receptors, causing the receptors to transduce signal inappropriately in the absence of the normal stimulus.

76
Q

Which family of receptors form the largest family of cell surface receptors?

A

GPCR

77
Q

Why are GPCRs an attractive target for the development of drugs to treat many disorders?

A

They mediate responses to an enormous diversity of extracellular signal molecules and are involved in a large variety of cell processes.

78
Q

About 1/3 of all drugs are used today to work through ___.

A

GPCRs

79
Q

What are the 2 main types of GTP binding proteins that participate in intracellular signaling pathways?

A

1- Large, trimeric GTP-binding proteins (aka G proteins); 2- Small, monomeric GTPases

80
Q

The monomeric GTP-binding proteins are aided by two sets of regulatory proteins. ____ activate the switch proteins by promoting the exchange of GDP for GTP. And ____ turn them off by promoting GTP hydrolysis.

A

Guanine nucleotide exchange factors (GEFs); GTPase-activating proteins (GAPs)

81
Q

GPCR is the G protein. True or false?

A

False. GPCR is the receptor.

82
Q

GPCR is a ___.

A

receptor

83
Q

Monomeric GTPase activate when GEFs promote the exchange of ___ for ___.

A

GDP; GTP

84
Q

Monomeric GTPase are inactivate when GAPs stimulate the hydrolysis of __ to ___.

A

GTP to GDP

85
Q

G proteins and monomeric GTPases are active when GTP is bound and inactive when GDP is bound. True or false?

A

True

86
Q

___ activate G-proteins upon signal binding.

A

GPCRs.

87
Q

What are the 3 subunits for G-proteins? Which one binds to GTP?

A

alpha, beta, gamma; alpha

88
Q

GPCR acts as a __ for the G-protein **activating** the alpha and beta-gamma subunits.

A

GEF (guanine exchange factor)

89
Q

When a G-protein-coupled activates a G protein, what happens?

A

The alpha subunit exchanges its bound GDP for GTP.

90
Q

Both the GTP-bound alpha subunits and nucleotide-free beta-gamma complexes - but not GDP- bound, fully assembled G proteins - can activate other molecules downstream of GPCRs. True or false?

A

True. Both are involved in downstream message delivery.

91
Q

The amount of time that the alpha and beta-gamma subunits remain “switched on” determines how long a response lasts. True or false?

A

True

92
Q

This time is controlled by the behavior of the __ subunit has an intrinsic GTPase activity.

A

alpha

93
Q

As long as alpha subunit has GTP, it is off. True or False?

A

False. As long as alpha subunit has GTP, it is ON.

94
Q

The length of time a G protein will signal is determined by ____.

A

the GTPase activity of G-alpha

95
Q

Bacteria ___ G-protein activity.

A

exploit

96
Q

Vibrio cholerae produces ___ toxin. It prevents __ protein from hydrolyzing ___ in intestinal cells. It And constitutively active __ results in diarrhea and dehydration.

A

cholera; G_s; GTP; G_s

97
Q

Bordetella pertussis produces __ toxin. It prevents the __ protein from exchanging GDP to GTP in the lungs. And constitutively inactive __ stimulates coughing.

A

pertussis; G_i; G_i

98
Q

G-protein-coupled receptors (GPCRs) all have a similar structure with ___ transmembrane domains.

A

7

99
Q

When a GPCR binds an extracellular signal an intracellular G protein, composed of __- subunits, become acticated.

A

3

100
Q

__ of the G-protein subunits are tethered to the plasma membrane by short lipid tails.

A

2

101
Q

When unstimulated, the alpha subunit is bound to ___, which is exchanged for ___ on stimlation.

A

GDP; GTP;

102
Q

The intrinsic ___ activity of the alpha subunit is important for inactivating the G protein.

A

GTPase

103
Q

___ inhibits this activity of the alpha subunit, thereby keeping the subunit in an active site.

A

Cholera

104
Q

Some G-proteins regulate ion channels. This is __ response.

A

rapid

105
Q

Heart muscle cells is an example of __ response.

A

rapid

106
Q

In the heart muscle cells, the acetylcholine ___ muscle contraction via ___ signaling cascade.

A

inhibits; GPCR

107
Q

Binding of the neurotransmitter ___ to its GPCR on the heart cells results in the activation of the G protein, G_i.

A

acetylcholine

108
Q

The ___ directly opens a __ channel in the plasma membrane, increasing its permeability to __ and thereby making the membrane harder to activate and ___ the heart rate.

A

activated beta-gamma complex; K+; K+; slowing

109
Q

Inactivation of the __ by hydrolysis of its bound GTP returns the G protein to its inactive state, allowing the __ channel to close.

A

alpha; K+

110
Q

G-proteins can activate membrane-bound enzymes creating __ or __ messengers.

A

small; second

111
Q

What is the second messenger for the following enzyme: adenylyl cyclase?

A

cyclic AMP (cAMP)

112
Q

What is the second messenger for the following enzyme: phospholipase C?

A

IP3 and DAG

113
Q

Second messenger molecules ___ to act on intracellular signaling proteins.

A

diffuse

114
Q

The alpha subunit of G_s activates ____ generating ___ from ATP.

A

adenylyl cyclase; cAMP

115
Q

cAMP activates cyclic-AMP-dependent ___.

A

PKA

116
Q

PKA __ other proteins changing their activity.

(Think… What does PKA stand for?)

A

phosphorylates

117
Q

cyclic AMP phosphodiesterase continuously converts ___ to ___ (down-regulating the activity).

A

cAMP; AMP

118
Q

Caffeine acts as a stimulant by inhibiting ___ in the nervous system, blocking cyclic AMP ___ and keeping the concentration of cyclic AMP ___.

A

cyclic AMP phosphodiesterase; degradation; high

119
Q

Give an example where the response to a signal and the increase in cAMP can be rapid. Why does this occur?

A

Skeletal muscle; These reactions do not involve changes in gene transcription or new protein synthesis

120
Q

Give an example where the response to a signal and the increase in cAMP can be slow.

A

neuronal learning memory

121
Q

G_q activates ____ which cleaves ____ to form the second messengers ___ and ___.

A

phospholipase C; inositol phospholipid; IP3; DAG

122
Q

Vasopressin (a peptide hormone) a) Targets what tissue? b) What’s the major response?

A

a) liver b) glycogen breakdown

123
Q

Acetylcholine. If the target tissue is the pancreas, what is the major response?

A

secretion of amylase (a digestive enzyme)

124
Q

Acetylcholine. If the target tissue is the skeletal muscle, what is the major response?

A

contraction

125
Q

Thrombin (a proteolytic enzyme) a) Targets what tissue? b) What’s the major response?

A

a) blood platelets; b) aggregation

126
Q

Which of the following types of cell signaling is long range and uses hormones as signals?

A

Endocrine

127
Q

The first step in a signaling pathway that responds to a molecule that stays in the extracellular space is…

A

binding of the signal molecule to a receptor.

128
Q

The active form of a monomeric GTP-binding protein is the…

A

GTP-bound form.

129
Q

What type of cell response would take the longest amount of time (on the scale of minutes to hours) to execute?

A

one that involves a change in gene expression

130
Q

The length of time a G protein will signal is determined by _______.

A

the GTPase activity of Gα.

131
Q

Foreign substances like nicotine, morphine, and menthol exert their initial effects by _____.

A

interacting with cell-surface receptors, causing the receptors to transduce signal inappropriately in the absence of the normal stimulus.

132
Q

One of the two types of GTP-binding proteins, often called G-proteins, are membrane bound. These are the

A

trimeric GTP-binding proteins.

133
Q

Which of the following would produce the fastest response to G-protein activation?

A

ion channel activation

134
Q

Signaling molecules that a cell secretes may act as local mediators, affecting only cells in the immediate environment of the signaling cell, in a process called________________________.

A

paracrine

135
Q

All members of the steroid hormone receptor family are found where in the cell?

A

Cytosol

136
Q

. Circle the phrase in each pair that is likely to occur more rapidly in response to an extracellular signal.

A. changes in cell secretion / increased cell division

B. changes in protein phosphorylation/changes in proteins being synthesized

C. changes in mRNA levels / changes in membrane potential

A

A. changes in cell secretion
B. changes in protein phosphorylation
C. changes in membrane potential

137
Q

Given the generic signaling pathway in the figure below, write the number corresponding to the item on the line next to the descriptor.

A

Receptor Protein 2
Effector proteins 4
Intracellular signaling proteins 3
Ligand 1

138
Q

Match the cell-surface receptors with the best description of function. Not all descriptors will be used.
G-protein-coupled receptors ______
ion-channel-coupled receptors ______
enzyme-coupled receptors ______

A. alter the membrane potential directly by changing the permeability of the plasma membrane
B. signal by opening and closing in a ligand-independent manner
C. must be coupled with intracellular monomeric GTP-binding proteins
D. all receptors of this class are polypeptides with seven transmembrane domains
E. discovered for their role in responding to growth factors in animal cells

A

D
A
E

139
Q

Two main types of protein kinases operate in intracellular signaling pathways: the most common are

A

1- serine/threonine kinases;

2- tyrosine kinases

140
Q

What are the two main types of GTP binding proteins that participate in intracellular signaling pathways?

A

1- Large, trimeric GTP-binding proteins (also called G proteins);

2- small, monomeric GTPases

141
Q

Which binding proteins relay messages from G-proteins-coupled receptors (GPCR)?

A

Large, trimeric GTP-binding proteins (also called G proteins)

142
Q

Which binding proteins to help relay their signals

A

small, monomeric GTPases

143
Q

These monomeric GTP-binding proteins are aided by two sets of regulatory proteins. What are they?

A

1- Guanine nucleotide exchange factors (GEFs)

2- GTPase-activating proteins (GAPs)

144
Q

a) What activates the switch proteins by promoting the exchange of GDP for GTP?
b) What turns the above off by promoting GTP hydrolysis?

A

a) Guanine nucleotide exchange factors (GEFs)
b) GTPase-activating proteins (GAPs)

BIOL 3510 - Cell Biology Lecture (17 decks)

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