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Cell Biology > ch.17 > Flashcards

ch.17 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

In terms of postal service, what is the ligand similar to?

A

the letter in the mail

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2
Q

In terms of postal service, what is the receptor similar to?

A

the mailbox

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3
Q

In terms of postal service, what is the signal transduction pathway similar to?

A

how you respond to the letter

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4
Q

In terms of postal service, what is the cell response similar to?

A

finalize by sending back a letter

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5
Q

True or False: Ligands can be hydrophobic or hydrophilic.

A

true

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6
Q

What kind of interaction does a receptor have?

A

cell surface or intracellular

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7
Q

describe direct cell-cell signaling.

A

proteins on the surface of the cells bind to each other

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8
Q

What are the 3 categories based on the distance over which signals are transmitted?

A

endocrine, paracrine, synaptic

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9
Q

describe endocrine signaling

A

for long distance; goes to blood; interaction between hormone and receptor is high affinity

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10
Q

describe paracrine signaling

A

molecules released by one cell act on neighboring target cells

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11
Q

describe autocrine signaling

A

cells respond to signaling molecules that they themselves produce

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12
Q

Which type of signaling is more precise than endocrine signaling?

A

synaptic signaling

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13
Q

Which type of signaling has rapid transmission of signals?

A

synaptic signaling

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14
Q

What are the sex steroids, produced by the gonads?

A

testosterone, estrogen, and progesterone

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15
Q

What makes cyclic GMP?

A

guanylyl cyclase

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16
Q

what binds to guanylyl cyclase?

A

Nitric oxide (NO)

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17
Q

What does cGMP induce?

A

muscle cell relaxation and blood vessel dilation

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18
Q

define second messenger

A

molecule that relays a signal from a receptor to a target inside the cell

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19
Q

cGMP is an important what?

A

second messenger

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20
Q

What happens when it is dark (in terms of cGMP)?

A

high levels of cGMP, cGMP binds to Na+ channels, Na+ rushes in + depolarizes the photoreceptor in the retina, Ca2+ channels open, Ca2+ leads the fusion of vesicles to release inhibitory neurotransmitters, inhibits any signals from continuing

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21
Q

What happens when it is light (in terms of cGMP)?

A

the 11-retinal changes to all trans, leads to the activation of the phosphodiesterase, GMP, Na+ is not rushing in, No vesicles releasing neurotransmitters, no longer inhibit vision

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22
Q

acetylcholine causes what?

A

skeletal muscle contraction + causes heart cells to relax

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23
Q

Are neurotransmitters hydrophobic or hydrophilic?

A

hydrophilic

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24
Q

Many neurotransmitter receptors are ________

A

ligand-gated ion channels

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25
Q

Enkephalins and endorphins act as what?

A

neurotransmitters and as neurohormones

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26
Q

define neurohormones

A

natural analgesics that decrease pain responses

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27
Q

What binds to morphine receptors on brain cells?

A

neurohormones

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28
Q

What do nerve growth factors (NGF) regulate?

A

development and survival of neurons

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29
Q

What do epidermal growth factors (EGF) do?

A

stimulates cell proliferation

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30
Q

When are platelet-derived growth factors (PDGF) released?

A

during blood clotting at the site of the wound

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31
Q

What do PDGFs stimulate?

A

proliferation of fibroblasts, contributing to regrowth of the damaged tissue

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32
Q

what are fibroblasts important for?

A

making the connective tissue that all the cells grow on

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33
Q

what do cytokines regulate?

A

development and differentiation of blood clots + activities of lymphocytes during the immune response

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34
Q

membrane-anchored growth factors remain where?

A

within the plasma membrane

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35
Q

what’s the function membrane-anchored growth factors?

A

signaling molecules in direct cell-cell interactions

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36
Q

Most ligands responsible for cell-cell signaling bind where?

A

surface receptors on target cells

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37
Q

what does intracellular signal transduction regulate?

A

surface receptors regulate intracellular enzymes

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38
Q

What do intracellular enzymes do?

A

transmit signals from the receptor to a series of additional intracellular targets

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39
Q

What is the largest family of cell surface receptors?

A

G protein-coupled receptors

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40
Q

How many times do the G protein-coupled receptors pass through the membrane (spanning alpha helices)?

A

7

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41
Q

In G protein-coupled receptors, how are signals transmitted?

A

guanine nucleotide-binding proteins (G proteins/GTPases)

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42
Q

What are the 3 subunits of the large G protein?

A

alpha, beta, and gamma

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43
Q

define heterotrimeric G proteins?

A

distinguishes large G proteins from other guanine nucleotide-binding proteins

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44
Q

The regulator G protein signal encourages what?

A

to chop off the terminal phosphate (acts like a GAP)

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45
Q

What do G proteins connect?

A

receptors to distinct targets (also regulate ion channels)

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46
Q

______ _____ cells have acetylcholine receptors that are G protein-coupled.

A

Heart muscle

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47
Q

The alpha subunit of the G protein in heart muscle cells (Gi) does what?

A

inhibits adenylyl cyclase

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48
Q

The beta-gamma subunits in heart muscle cells does what?

A

opens K+ channels in the plasma membrane

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49
Q

What slows heart muscle contraction?

A

when beta-gamma subunits open K+ channels in the plasma membrane

50
Q

What is the role of cAMP as a second messenger?

A

signals the breakdown of glycogen to glucose in muscle cells

51
Q

How is cAMP formed?

A

from ATP by adenylyl cyclase

52
Q

how is cAMP degraded to AMP?

A

by cAMP phosphodiesterase

53
Q

What is cAMP mediated by?

A

cAMP-dependent protein kinase or protein kinase A (PKA)

54
Q

Glycogen metabolism PKA phosphorylates how many enzymes?

A

2

55
Q

Describe signal amplification.

A

binding of a hormone molecule leads to activation of many intracellular target enzymes

56
Q

Each receptor may activate up to 100 molecules of ____

A

Gs

57
Q

In many animal cells, cAMP activates what?

A

transcription of genes that have a regulatory sequence called cAMP response element (CRE)

58
Q

Free catalytic subunit of protein kinase A goes to the nucleus and phosphorylates transcription factor______ ______.

A

CREB (CRE-binding protein)

59
Q

Phosphorylation of CREB leads to what?

A

recruitment of coactivators and expression of cAMP-inducible genes

60
Q

When is the target protein active?

A

When protein kinase A phosphorylates ATP (to add a phosphate to the target protein)

61
Q

Odorant receptors are _____________

A

G protein-coupled

62
Q

What stimulates adenylyl cyclase?

A

second messengers

63
Q

The opening of Na+ channels in the plasma membrane leads to what?

A

the initiation of a nerve impulse

64
Q

Many cell surface receptors are directly linked to what?

A

intracellular enzymes

65
Q

What is the largest family of intracellular enzymes?

A

tyrosine kinases

66
Q

Most polypeptide growth factors work through what receptors?

A

receptor tyrosine kinases

67
Q

The human genome encodes how many receptor tyrosine kinases?

A

58

68
Q

Which terminus is the ligand-binding domain in receptor tyrosine kinases?

A

N-terminus

69
Q

Which terminus domain is the tyrosine kinase domain in receptor tyrosine kinases?

A

C-terminus

70
Q

Describe the receptor tyrosine kinases steps.

A

growth factor binds –> dimerize –> auto phosphorylate

71
Q

What are the 2 roles of autophosphorylation?

A

1) phosphorylation of tyrosine in the catalytic domain
2) phosphorylation of tyrosine outside the catalytic domain

72
Q

Phosphorylation of tyrosine in the catalytic domain does what?

A

increases protein kinase activity

73
Q

Phosphorylation of tyrosine outside the catalytic domain creates what?

A

binding sites for other proteins that transmit signals downstream from the activated receptors

74
Q

What are the 4 signaling molecule domains?

A

1) Src Homology 2 (SH2)
2) Phosphotyrosine binding (PTB)
3) Src homology 3 (SH3)
4) pleckstrin homology (PH)

75
Q

Which of the 4 signaling molecule domains bind to phosphorylated tyrosine?

A

SH2 + PTB

76
Q

Which of the 4 signaling molecule domains bind to proline rich regions?

A

SH3

77
Q

nonreceptor tyrosine kinases stimulate what?

A

intracellular tyrosine kinases with which they are noncovalently associated

78
Q

cytokine receptor superfamily includes what?

A

receptors for most cytokines and some polypeptide hormones

79
Q

Janus kinase (JAK) family

A

kinases associated with cytokine receptors

80
Q

What are key targets of JAK kinases?

A

STAT proteins

81
Q

STAT proteins are what?

A

transcription factors with SH2 domains

82
Q

STAT proteins are inactive in the cytosol until what?

A

cytokine receptors are stimulated

83
Q

What can JAK phosphorylate?

A

JAK, receptor, STAT

84
Q

Once STAT proteins are phosphorylated, what happens?

A

the STAT proteins dimerize and translocate to the nucleus

85
Q

MAP kinase pathway is what?

A

a cascade of protein kinases found in all eukaryotic cells

86
Q

what do MAP kinases do?

A

mitogens activate mitosis

87
Q

MAP kinases involve what amino acid kinases?`

A

serine + threonine kinases

88
Q

MAP kinases first found in mammalian cells belong to the ____.

A

ERK family (extracellular signal-regulated kinase)

89
Q

ERK signaling emerged from the studies of what?

A

Ras proteins

90
Q

Ras proteins are activated by what?

A

GEFs (guanine nucleotide exchange factors)

91
Q

What do GEFs stimulate the exchange of?

A

GDP for GTP

92
Q

Ras-GTP activity is terminated by what?

A

GTP hydrolysis –> stimulated by interaction of Ras-GTP with GAPs

93
Q

Some activated ERK goes to the nucleus, where it does what?

A

regulates transcription factors by phosphorylation

94
Q

_____ and ______ cells have multiple MAP kinase pathways

A

yeast and mammalian

95
Q

Each cascade consists of 3 protein kinases…

A

terminal MAP kinase + 2 upstream kinases

96
Q

What do mammalian MAP kinases include?

A

ERK, JNK, and p38 kinases

97
Q

Specificity of MAP kinase signaling is maintained partly by what?

A

physical association on scaffold proteins

98
Q

PI 3-kinase/Akt pathway is based on what?

A

a second messenger derived from the membrane phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2)

99
Q

What is PIP2 phosphorylated by?

A

phosphatidylinositide (PI) 3-kinase

100
Q

What is PI 3-kinase recruited to?

A

activated receptor tyrosine kinases via its SH2 domain

101
Q

PIP3 targets a _______/________ kinase called Akt via its pleckstrin homology (PH) domain.

A

serine/threonine

102
Q

What is Akt phosphorylated and activated by?

A

PDK1

103
Q

Activation of Akt also requires phosphorylation by protein kinase _______, which is also stimulated by growth factors.

A

mTORC2

104
Q

Akt phosphorylates several target proteins such as what?

A

transcription factors (FOXO)

105
Q

Akt phosphorylation of FOXO sequesters it in ______ form in the cytosol.

A

inactive

106
Q

The mTORC1 complex is activated ______ of Akt.

A

downstream

107
Q

what does mTORC1 regulate?

A

cell size by controlling protein synthesis

108
Q

mTORC1 also inhibits _______ ________ by regulating autophagy.

A

protein degradation

109
Q

What happens in the phospholipase C/calcium pathway?

A

hydrolysis of PIP2 by phospholipase c

110
Q

what are the 2 second messengers that phospholipase c produces?

A

DAG and IP3

111
Q

where is DAG located?

A

remains associated with the plasma membrane

112
Q

what does DAG activate?

A

serine/threonine kinases of the protein kinase c family

113
Q

what does IP3 bind to?

A

receptors that are ligand-gated Ca2+ channels in the ER

114
Q

What is one of the major Ca2+ binding proteins that mediates the effects of Ca2+

A

calmodulin

115
Q

when is calmodulin activated?

A

when Ca2+ concentration increases

116
Q

members of the ______ kinase family are also activated by Ca2+/calmodulin.

A

CaM

117
Q

One form of CaM kinase regulates what?

A

synthesis and release of neurotransmitters

118
Q

In the TGF-B/Smad pathway, receptors for transforming growth factor B (TGF-B) directily phosphorylate transcription factors of the _____ family.

A

Smad

119
Q

Wnt proteins are what?

A

Growth factors that bind to receptors of the Frizzled and LRP families

120
Q

signaling from frizzled and LRP leads to what?

A

stabilization of β-catenin, a transcriptional activator

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