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Biology 224 > Chapter 9, Cell Communication > Flashcards

Chapter 9, Cell Communication Flashcards

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1
Q

Cell signaling involves both

A

incoming and outgoing signals

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2
Q

A signal is…

A

an agent that can influence the properties of cells

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3
Q

Signals are recognized by

A

receptors

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4
Q

Receptors cause…

A

a cellular response (shape/activity altered due to binding of signal)

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5
Q

5 basic types of singaling

A
  • Direct Intercellular Signaling
  • Contact-dependent Signaling
  • Autocrine Signaling
  • Paracrine Signaling
  • Endocrine Signaling
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6
Q

Direct intercellular signaling

A
  • cell junctions may allow signals to pass directly between cells
  • gap junctions are an example
  • proteins and protein channels involved
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7
Q

Contact dependent signaling

A
  • one cell has membrane-bound signal recognized by a receptor to another cell
  • only way is to come in contact with each other
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8
Q

Autocrine Signaling

A
  • cell secretes signal/chemical that bind to receptors on their OWN SURFACE and also surfaces of NEIGHBORING CELLS and the SAME TIME, stimulating BOTH

***only affects neighboring cells of the SAME TYPE

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9
Q

Paracrine Signaling

A
  • Cell secretes signal that binds to receptors and influences JUST target cells in CLOSE PROXIMITY
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10
Q

Endocrine Signaling

A
  • Cell secretes a hormone into bloodstream that affects cells FAR AWAY from source of signal
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11
Q

3 step cellular response to signals

A

1 - receptor activation (binds and becomes activated)
2 - signal transduction (conversion) (signal converted to internal signal, need to convert to something cell can understand)
3 - cellular response (only then can cell respond)

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12
Q

1 - Receptor Activation

A

the signaling molecule binds to receptor causing CONFORMATIONAL CHANGE in the receptor which activates its function

ligands that bind are non-covalent and temporary

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13
Q

2 - Signal Transduction

A
  • most signals are hydrophilic and can not enter cells through membrane
  • so initial signal is transduced/converted to 2nd signal inside the cell
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14
Q

3 - Cellular response (3)

A
  • many activate enzymes inside the cell
  • some alter function of structural proteins in the cell
  • some affect function of transcription factors, proteins that bind to and regulate activity of genes directly
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15
Q

There are ___ different types of receptors for step one (receptor activation

A

five

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16
Q

(#1, receptor activation) ligands are..

A

signals that bind non-covalently and temporarily to receptors

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17
Q

(#1, receptor activation) the binding of the ligand…

A

changes the receptor and activiates its ability to initiate the cellular responce

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18
Q

(#1, receptor activation) Binding is..

A

temporary and reversable

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19
Q

(#1, receptor activation) when ligand is released…

A

the receptor is no longer activated

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20
Q

(#1, receptor activation) cell surface receptors are necessary because..

A

most signals are hydrophilic or large molecules that will not diffuse through plasma membrane

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21
Q

(#1, receptor activation) many cells need…

A

surface (membrane bound) receptors to bind signals

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22
Q

There are ___ different types of receptors

A

five

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23
Q

Five types are…(A-E)

A
  • (A) enzyme linked receptors
  • (B) G protein-coupled receptors
  • (C) Ligand-gated ion channels
  • (D) Intracellular Receptors
  • (E) Receptor Tyrosine Kinases
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24
Q

(A) Enzyme linked receptors have receptor in…

A

extracellular matrix where the signal binds

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25
Q

(A) Signal can be…

A

hormone, ligand, signal, all the same

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26
Q

(A) When the extracellular domain is bound…

Intracellular domain has a ____ function

A

the intracellular domain is activated

Has catalytic function

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27
Q

(A) Most enzyme linked receptors have a…

A

protein kinase function in intracellular domain

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28
Q

(A) This protein kinase function means…

A

leads to phosphorylation of other proteins (removes phosphate from ATP and attaches it to protein)

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29
Q

(A) The phosphorylated protein is then

A

ACTIVATED to cause a CELLULAR RESPONCE

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30
Q

(B) The G Protein-coupled receptors have G proteins which are named for…

A

ability to bind to GTP as a substrate

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31
Q

(B) The G Protein-coupled receptors typically have….

A

7 transmembrane segments which embed them in the plasma membrane

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32
Q

(B) G proteins have…

A

two subunits, alpha and beta/gamma subunit

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33
Q

(B) When bound by signal…

A

the receptors intracellular domain contacts and causes G protein to release GDP and bind to GTP

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34
Q

(B) When bound to GTP

A

the alpha subunit dissociates from the beta/gamma subunit

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35
Q

(B) After alpha subunit dissociates..

A

the alpha subunit is then activated and free to initiate cellular responce

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36
Q

(B) When the original signal dissociates…

A

process is reversed - alpha subunit splits GTP to GDP, which allows alpha to re-bind to beta/gamma, which inactivates G protein and ends cellular responce

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37
Q

(C) Ligan gated ion channels is when…

A

signal (ligand) binds to receptor, it changes CONFORMATION and open channel for ions to flow

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38
Q

(C) example of ligand gated ion channel is

A

facilitated diffusion, flow down concentration

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39
Q

(D) intracellular receptors are…

A

steroid (hormones), therefore lipids meaning they can pass through the plasma membrane and go right to nucleus

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40
Q

(D) The receptors are…

A

intracellular and bind the signal to cause CONFORMATIONAL change in receptor, which ACTIVATES IT

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41
Q

(D) The active signal/receptor complex is found in…and…

A

nucleus, binds specific genes (acting as transcription factors) to activate them

42
Q

(D) cellular response of intracellular receptors are

A

protein production

43
Q

(E) Epidermal Growth Factors is…

A

a hormone that activates a receptor tyrosine kinase

44
Q

(E) EGF is a hormone which…(cell response)

A

stimulates cell division in the body

45
Q

(E) EGF hormone is…

A

secreted by endocrine cells into the blood and carried throughout the body

46
Q

(E) First part of receptor tyrosine kinases is…

A

2 epidermal growth factors EACH bind a receptor (there are always 2 receptors), which when they phosphorylate the tyrosine on each other

47
Q

(E) The now activated receptor…

A

activates Grb, which then binds and activates Sos

48
Q

(E) activating Sos causes…

A

Ras to release GDP and bind to GTP, which activates Ras

49
Q

(E) Ras is…

A

the first kinase in an enzyme/protein kinase cascade

50
Q

(E) Ras…

A

binds to and phosphorylates Raf, which then binds and phosphorylates Mek, which then binds and Phospohorylates Erk

Ras –> Raf –> Mek –> Erk

51
Q

(E) Erk then…

A

enters the nucleus and phosphorylates transcription facts like Myc and Fos

52
Q

(E) Myc and Fos are just

A

transcription facts in activated forms which lead to produce proteins that stimulate cellular division

53
Q

Since most signal cant physically enter the cell…

A

they depend on a second messenger to carry on signal and produce cellular response

54
Q

Seconds messengers typically…

A

produce quick and short cellular responses

55
Q

________ is original messenger, then once inside the cell it needs a second messenger

A

ligand

56
Q

In Signal Transduction, when G protein receptors activate G proteins…

A

alpha subunits are freed up, which activate a variety of other proteins

57
Q

One common enzyme activated by alpha subunit is…

A

Adenylyl Cyclase

58
Q

Adenylyl Cyclase is a…

A

membrane-bound enzyme attached to the INTERIOR of plasma membrane

59
Q

The function of Adenylyl Cyclase is to…

A

remove pyrophosphate (2 phosphates) from ATP producing cyclic AMP (cAMP)

60
Q

cAMP is…

A

a common second messenger

61
Q

One common effect of cAMP is to…

A

activate protein kinase A (PKA)

62
Q

PKA has..

A

two catalytic subunits (REGULATORY AND CATALYTIC) which phosphorylate and activate other proteins

63
Q

cAMP binds…which then…

A

the regulatory subunits of PKA which frees them from the catalytic subunits, which then free catalytic subunits to activate

64
Q

Active PKA uses PO4 groups from ATP to…

A

phosphorylate and activate other proteins, causing cellular responce

65
Q

Second messengers have…

A

short durations

66
Q

How does cAMP get separated from PKA

A

Phosphodiesterase hydrolyzes (break down using water) cAMP to AMP, removing it from regulatory subunits of PKA

67
Q

The regulatory subunits then…

A

rebind the catalytic subunits of PKA, inactivating them

68
Q

G proteins can also…

A

activate enzymes other than adenylyl cyclase

69
Q

(G proteins can activate other enzymes other than adenylyl cyclase) When another different signal is bound to G protein-coupled receptor…

A

activated G protein alpha subunit activates phospholipase C

70
Q

The Phospholipase C…

A

cleaves phosphatidyl-inositol releasing Diacyglycerol (DAG) and Inositol Phosphate (IP3), BOTH ARE SECOND MESSENGERS

71
Q

IP3 will…

And the result is…

A

bind to ligand-gated Ca2+ channel in the ER membrane, opening the channel

Ca+ has been actively transported into Er, when the channel opens, Ca+ flows out, which is A SIGNAL, telling cell to do something

72
Q

Ca2+ is…

A

a second messenger

73
Q

Ca2+ along with __________…

A

Diacylglycerol (DAG) it binds and activates protein kinase C

74
Q

PKC …

A

phosphorylates other proteins

75
Q

Ca2+ by itself…

A

can also bind and activate the protein Calmodulin, which in turn alters the function of still other cellular proteins

76
Q

Advantages to second messengers (3)…

A
  • AMPLIFY signal so that each successive step in pathway produces more and more messengers
  • generally small and hydrophobic
  • this allows them to rapidly diffuse throughout the cell to produce a QUICK RESPONSE
77
Q

Hormones are…

A

chemicals secreted in minute quantities into the bloodstream which have effects in DISTANT parts of body

78
Q

Hormones can produce

A

a diverse set of responses throughout the body

79
Q

Hormones can either be…

A
  • steroid and enter directly through the membrane
  • proteins and bind receptors to product second messengers
80
Q

Divergent effects because #1

A
  • only cells with receptors for that hormone can respond to hormone
81
Q

Divergent effects because #2

A
  • different receptors may recognize the same hormone, and different receptors produce different effects in cells
82
Q

Divergent effects because #3

A

different receptors have different affinities/sensitivites for a hormone, so depending on CONCENTRATION, some will respond and others will not

83
Q

Divergent effects because #4

A
  • different cells have different transduction pathways, so they respond differently
84
Q

Divergent effects because #5

A

different cell types may not express certain proteins, even if they are stimulated

85
Q

Example of #5 reason is…

A

glycogen breakdown will not accur under influence of epiniphrine/adrenaline is the enzyme (glycogen phosphorylase) is not expressed in particular cell

86
Q

Apoptosis is

A

cellular death

87
Q

Death of some cells during development…

A

is normal and helps form the organs of the body

88
Q

BMP4 is

A

a signal that causes cells to undergo apoptosis and die

89
Q

Gremlin is

A

a signal that inhibits the function of BMP4 and allows cells to survive

90
Q

Duck originally has BMP4 that is released to tell the webbed cells to die but…

A

Gremlin is released after to stop cells from dying

91
Q

Other cells experiencing extensive damage…

A

are programmed to die rather than damage other cells and the life of the whole organism

92
Q

Intrinsic pathways are

A

patways that begin and end inside cell

93
Q

Extrinsic pathways are

A

pathways that begin on outer and end inner

94
Q

Both intrinsic and extrinsic pathways

A

lead to apoptosis

95
Q

Internal cell damage..

A

such as massive damage to DNA can produce internal signals leading to apoptosis

96
Q

Surface proteins on Mitochondria..

A

play key role in this Intrinsic pathway leading to apoptosis

97
Q

Death Receptors are an example of…

A

EXTRINSIC pathways in cell membrane leading to apoptosis in cell

98
Q

These death receptors, when bound by a signal…

A

initiate a cellular response leading to programmed cell death

99
Q

Virus example of

A

EXTRINSIC pathway

100
Q

Virus apoptosis example is when…

A

cell infected with virus may be signaled to die, thereby removing the virus from organism rather than allowing infection to spread

101
Q
A

Biology 224 (18 decks)

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