Chapter 9, Cell Communication Flashcards
1
Q
Cell signaling involves both
A
incoming and outgoing signals
2
Q
A signal is…
A
an agent that can influence the properties of cells
3
Q
Signals are recognized by
A
receptors
4
Q
Receptors cause…
A
a cellular response (shape/activity altered due to binding of signal)
5
Q
5 basic types of singaling
A
- Direct Intercellular Signaling
- Contact-dependent Signaling
- Autocrine Signaling
- Paracrine Signaling
- Endocrine Signaling
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
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
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
9
Q
Paracrine Signaling
A
- Cell secretes signal that binds to receptors and influences JUST target cells in CLOSE PROXIMITY
10
Q
Endocrine Signaling
A
- Cell secretes a hormone into bloodstream that affects cells FAR AWAY from source of signal
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)
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
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
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
15
Q
There are ___ different types of receptors for step one (receptor activation
A
five
16
Q
(#1, receptor activation) ligands are..
A
signals that bind non-covalently and temporarily to receptors
17
Q
(#1, receptor activation) the binding of the ligand…
A
changes the receptor and activiates its ability to initiate the cellular responce
18
Q
(#1, receptor activation) Binding is..
A
temporary and reversable
19
Q
(#1, receptor activation) when ligand is released…
A
the receptor is no longer activated
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
21
Q
(#1, receptor activation) many cells need…
A
surface (membrane bound) receptors to bind signals
22
Q
There are ___ different types of receptors
A
five
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
24
Q
(A) Enzyme linked receptors have receptor in…
A
extracellular matrix where the signal binds
25
(A) Signal can be...
hormone, ligand, signal, all the same
26
(A) When the extracellular domain is bound...
Intracellular domain has a ____ function
the intracellular domain is activated
Has catalytic function
27
(A) Most enzyme linked receptors have a...
protein kinase function in intracellular domain
28
(A) This protein kinase function means...
leads to phosphorylation of other proteins (removes phosphate from ATP and attaches it to protein)
29
(A) The phosphorylated protein is then
ACTIVATED to cause a CELLULAR RESPONCE
30
(B) The G Protein-coupled receptors have G proteins which are named for...
ability to bind to GTP as a substrate
31
(B) The G Protein-coupled receptors typically have....
7 transmembrane segments which embed them in the plasma membrane
32
(B) G proteins have...
two subunits, alpha and beta/gamma subunit
33
(B) When bound by signal...
the receptors intracellular domain contacts and causes G protein to release GDP and bind to GTP
34
(B) When bound to GTP
the alpha subunit dissociates from the beta/gamma subunit
35
(B) After alpha subunit dissociates..
the alpha subunit is then activated and free to initiate cellular responce
36
(B) When the original signal dissociates...
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
37
(C) Ligan gated ion channels is when...
signal (ligand) binds to receptor, it changes CONFORMATION and open channel for ions to flow
38
(C) example of ligand gated ion channel is
facilitated diffusion, flow down concentration
39
(D) intracellular receptors are...
steroid (hormones), therefore lipids meaning they can pass through the plasma membrane and go right to nucleus
40
(D) The receptors are...
intracellular and bind the signal to cause CONFORMATIONAL change in receptor, which ACTIVATES IT
41
(D) The active signal/receptor complex is found in...and...
nucleus, binds specific genes (acting as transcription factors) to activate them
42
(D) cellular response of intracellular receptors are
protein production
43
(E) Epidermal Growth Factors is...
a hormone that activates a receptor tyrosine kinase
44
(E) EGF is a hormone which...(cell response)
stimulates cell division in the body
45
(E) EGF hormone is...
secreted by endocrine cells into the blood and carried throughout the body
46
(E) First part of receptor tyrosine kinases is...
2 epidermal growth factors EACH bind a receptor (there are always 2 receptors), which when they phosphorylate the tyrosine on each other
47
(E) The now activated receptor...
activates Grb, which then binds and activates Sos
48
(E) activating Sos causes...
Ras to release GDP and bind to GTP, which activates Ras
49
(E) Ras is...
the first kinase in an enzyme/protein kinase cascade
50
(E) Ras...
binds to and phosphorylates Raf, which then binds and phosphorylates Mek, which then binds and Phospohorylates Erk
Ras --> Raf --> Mek --> Erk
51
(E) Erk then...
enters the nucleus and phosphorylates transcription facts like Myc and Fos
52
(E) Myc and Fos are just
transcription facts in activated forms which lead to produce proteins that stimulate cellular division
53
Since most signal cant physically enter the cell...
they depend on a second messenger to carry on signal and produce cellular response
54
Seconds messengers typically...
produce quick and short cellular responses
55
________ is original messenger, then once inside the cell it needs a second messenger
ligand
56
In Signal Transduction, when G protein receptors activate G proteins...
alpha subunits are freed up, which activate a variety of other proteins
57
One common enzyme activated by alpha subunit is...
Adenylyl Cyclase
58
Adenylyl Cyclase is a...
membrane-bound enzyme attached to the INTERIOR of plasma membrane
59
The function of Adenylyl Cyclase is to...
remove pyrophosphate (2 phosphates) from ATP producing cyclic AMP (cAMP)
60
cAMP is...
a common second messenger
61
One common effect of cAMP is to...
activate protein kinase A (PKA)
62
PKA has..
two catalytic subunits (REGULATORY AND CATALYTIC) which phosphorylate and activate other proteins
63
cAMP binds...which then...
the regulatory subunits of PKA which frees them from the catalytic subunits, which then free catalytic subunits to activate
64
Active PKA uses PO4 groups from ATP to...
phosphorylate and activate other proteins, causing cellular responce
65
Second messengers have...
short durations
66
How does cAMP get separated from PKA
Phosphodiesterase hydrolyzes (break down using water) cAMP to AMP, removing it from regulatory subunits of PKA
67
The regulatory subunits then...
rebind the catalytic subunits of PKA, inactivating them
68
G proteins can also...
activate enzymes other than adenylyl cyclase
69
(G proteins can activate other enzymes other than adenylyl cyclase) When another different signal is bound to G protein-coupled receptor...
activated G protein alpha subunit activates phospholipase C
70
The Phospholipase C...
cleaves phosphatidyl-inositol releasing Diacyglycerol (DAG) and Inositol Phosphate (IP3), BOTH ARE SECOND MESSENGERS
71
IP3 will...
And the result is...
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
Ca2+ is...
a second messenger
73
Ca2+ along with __________...
Diacylglycerol (DAG) it binds and activates protein kinase C
74
PKC ...
phosphorylates other proteins
75
Ca2+ by itself...
can also bind and activate the protein Calmodulin, which in turn alters the function of still other cellular proteins
76
Advantages to second messengers (3)...
- 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
Hormones are...
chemicals secreted in minute quantities into the bloodstream which have effects in DISTANT parts of body
78
Hormones can produce
a diverse set of responses throughout the body
79
Hormones can either be...
- steroid and enter directly through the membrane
- proteins and bind receptors to product second messengers
80
Divergent effects because #1
- only cells with receptors for that hormone can respond to hormone
81
Divergent effects because #2
- different receptors may recognize the same hormone, and different receptors produce different effects in cells
82
Divergent effects because #3
different receptors have different affinities/sensitivites for a hormone, so depending on CONCENTRATION, some will respond and others will not
83
Divergent effects because #4
- different cells have different transduction pathways, so they respond differently
84
Divergent effects because #5
different cell types may not express certain proteins, even if they are stimulated
85
Example of #5 reason is...
glycogen breakdown will not accur under influence of epiniphrine/adrenaline is the enzyme (glycogen phosphorylase) is not expressed in particular cell
86
Apoptosis is
cellular death
87
Death of some cells during development...
is normal and helps form the organs of the body
88
BMP4 is
a signal that causes cells to undergo apoptosis and die
89
Gremlin is
a signal that inhibits the function of BMP4 and allows cells to survive
90
Duck originally has BMP4 that is released to tell the webbed cells to die but...
Gremlin is released after to stop cells from dying
91
Other cells experiencing extensive damage...
are programmed to die rather than damage other cells and the life of the whole organism
92
Intrinsic pathways are
patways that begin and end inside cell
93
Extrinsic pathways are
pathways that begin on outer and end inner
94
Both intrinsic and extrinsic pathways
lead to apoptosis
95
Internal cell damage..
such as massive damage to DNA can produce internal signals leading to apoptosis
96
Surface proteins on Mitochondria..
play key role in this Intrinsic pathway leading to apoptosis
97
Death Receptors are an example of...
EXTRINSIC pathways in cell membrane leading to apoptosis in cell
98
These death receptors, when bound by a signal...
initiate a cellular response leading to programmed cell death
99
Virus example of
EXTRINSIC pathway
100
Virus apoptosis example is when...
cell infected with virus may be signaled to die, thereby removing the virus from organism rather than allowing infection to spread
101
