Chapter Nine: Cell Communication Flashcards
(102 cards)
1
Q
Cell signaling involves both ___________ and ___________ signals
A
incoming and outgoing
2
Q
Any agent that can influence the properties of cells
A
A Signal
3
Q
Signals are recognized by…
A
Receptors
4
Q
What are allosteric and cause a cellular response?
A
Receptors
5
Q
What type of signaling?
- cell junctions may allow signals to pass directly between cells
- Gap junctions would be an example
A
Direct Intercellular Signaling
6
Q
What type of Signaling?
One cell has a membrane-bound signal recognized by a receptor by a receptor on another cell
A
Contact-dependent Signaling
7
Q
What type of Signaling?
Cell Secretes a signal/chemical that bind to receptors on their own surface and that of neighboring cells of the same type, stimulating them
A
Autocrine Signaling
8
Q
What type of signaling?
Cell Secretes a signal that influences not themselves but target cells in close proximity
A
Paracrine Signaling
9
Q
What type of cell signaling?
Cell secretes a hormone into bloodstream that affects cells far from the source of the signal
A
Endocrine Signals
10
Q
What are the three step response to signals?
A
- Receptor Activation
- Signal Transduction
- Cellular Response
11
Q
The _________ ____________ binds to the Receptor causing a conformational change in the Receptor which activates its function
A
signaling molecule
12
Q
Most signals are ______________ and can not enter cells through the membrane
A
hydrophilic
13
Q
The initial signal is converted to a second signal _____________ the cell
A
inside
14
Q
Many signals activate _____________ inside the cell
A
enzymes
15
Q
Some signals alter the ___________ of structural proteins in the cell
A
function
16
Q
Some signals affect _________ that bind to and regulate the activity of genes directly
A
proteins
17
Q
What are signals that bind non-covalently and temporarily to Receptors?
A
Ligands
18
Q
What changes the receptor to activate the ability to initiate the cellular response?
A
binding
19
Q
Is binding temporary and reversible?
A
yes
20
Q
When the _________ is released, receptor is no longer activated
A
ligand
21
Q
The signal, often a _____________, binds the receptor
A
hormone
22
Q
Receptors have different ______________ for the signal
A
affinities (preferences)
23
Q
The Dissociation Constant (___) indicates the affinity
A
Kd
24
Q
A low Kd indicates a ________ affinity
A
high
25
Receptors are necessary because most signals are hydrophilic or large molecules that will not diffuse through the…
Plasma Membrane
26
Cells need _________ receptors to bind specific signals
surface
27
Enzyme-linked receptors have a receptor in the ____________ _________ where the signal, often a hormone, bonds
Extracellular matrix
28
The _______________ ____________ has a catalytic function
Intracellular Domain
29
When the Extracellular Domain is bound, the ________________ _____________ is activated
Intracellular Domain
30
Most Enzyme-linked receptors have a protein ____________ function in the intracellular domain
Kinase
31
When bound by a signal, the protein kinase will ______________ other proteins
phosphorylate
32
Protein Kinases ____________ a phosphate from ATP and attach it to a protein
remove
33
The phosphorylated protein is usually _____________ to cause a cellular response
activated
34
G Proteins are named for their ability to bind _______ as a substrate
GTP
35
The receptors typically have _____ transmembrane segments which embed it in the Plasma Membrane
7
36
G Proteins have what two subunits?
alpha and beta
37
When bound by a signal, the receptor’s intracellular domain causes the G protein to release _______ and bind ________
GDP
GTP
38
When bound to the GTP, the ___ subunit dissociates from the ____ subunit
alpha
beta
39
After the alpha subunit dissociates from the beta subunit, it is then _______ and free to initiate a cellular response
active
40
That alpha subunit splits GTP to GDP, which allows alpha to be bound by the beta subunit, ____________ the G protein, ending the cellular response
inactivating
41
When the signal (ligand) binds the receptor, it changes conformation and opens the channel for an _____ to flow
ion
42
Some signals are _________ (hormones) and pass through the Plasma Membrane
steroids
43
Do intracellular receptors require a second messenger?
no
44
Intracellular Receptors bind signal to cause a conformational change in the ____________, activating it
receptor
45
The active signal or receptor complex enters the __________ and binds specific genes to activate them
nucleus
46
What is a hormone that activates a Receptor Tyrosine Kinase?
Epidermal Growth Factor
47
What does the hormone EGF stimulate throughout the body?
Cell Division
48
Receptor Tyrosine Kinases are secreted by ________________ Cells into the blood and is carried throughout the body
Endocrine
49
Two Epidermal Growth Factors each bind a receptor, which binds and ________________ each other on tyrosine amino acids
phosphorylate
50
Receptor Tyrosine Kinases: the now activated receptor activates _______ which then binds and activates _______
Grb
Sos
51
Receptor Tyrosine Kinases: activated ______ causes Ras to release GDP and GTP bind, which activates Ras
Sos
52
Receptor Tyrosine Kinases: _____ is the first Kinase in an Enzyme cascade
Ras
53
Ras binds and phosphorylated Raf, which binds and phosphorylates…
Erk
54
Receptor Tyrosine Kinases: Erk then enters the Nucleus and phosphorylates ______________ factors like Myc and Fos
transcription
55
Receptor Tyrosine Kinases: They bind genes (maybe 100) which then produce ____________ that stimulate cell division
proteins
56
Since most signals can’t enter the cell, they depend on a ___________ ___________ to produce the cellular response
second messenger
57
Second Messengers typically produce quick and short ____________ responses
cellular
58
When G Protein Receptors activate G Proteins, the _______ subunit is freed up, in turn activates a variety of other proteins
alpha
59
One common enzyme activated by alpha subunits is…
Adenylyl Cyclase
60
Adenylyl Cyclase is a membrane-bound enzyme, attached to the interior of the…
Plasma Membrane
61
The function of Adenylyl Cyclase is to remove _________________ from ATP, producing cyclic AMP (cAMP)
pyrophosphate
62
cAMP is a common….
second messenger
63
One common effect of cAMP is to activate….(PKA)
Protein Kinase A
64
PKA has two Regulatory Subunits that repress the two Catalytic subunits which phosphorylate and activate other…
proteins
65
cAMP binds the ___________ subunits which frees them from the _____________ subunits
Regulatory
Catalytic
66
Once the Catalytic subunit is freed it is…
active
67
Active PKA uses PO4 groups from _______ to phosphorylate and activate other proteins, causing a cellular response
ATP
68
Second Messengers have _______ durations
short
69
Phosphodiesterase hydrolyses cAMP to ATP, removing it from the Regulatory subunits of…
PKA
70
The Regulatory subunits then rebind the _____________ subunits of PKA, inactivating them
Catalytic
71
When PKA is activated it phosphorylates Phosphorylase Kinase which activates Glycogen Phosphorylase, which cutes Glucose-Phosphate from _____________, making it available to muscles
Glycogen
72
PKA also phosphorylates Glycogen Synthase, inactivating it to promote ____________ breakdown rather than synthesis
Glycogen
73
G proteins can activate ___________ other than adenylyl cyclase
enzymes
74
_______ binds G Protein-coupled Receptor
Signal
75
Activated G Protein alpha subunit activates….
Phospholipids C
76
Phospholipase C cleaves Phospatidylinositol releasing Diacylglycerol and Inositol Phosphate (IP3), both of which are…
Second Messengers
77
IP3 will bind to a Ligand-gated Ca+ channel on the _____, opening the channel
ER
78
Ca+ is actively transported into the ER so when the channel opens, _____ flows out
Ca+
79
Ca+ is another __________ Messenger
Second
80
In conjunction with Diacylglycerol, Ca+ binds and activates…
Protein Kinase C
81
Ca+ by itself can also bind and activate the protein _____________, which in turn alters the function of still other cellular proteins
Calmodulin
82
Second messengers __________ the signal so that each successive step in the pathway produces more and more messengers
amplify
83
Second messengers are generally ________ and ______________
small and hydropholic
84
Second messengers being small and hydrophilic allows them to rapidly diffuse throughout the cell to produce a ________ response
quick
85
Hormones are chemicals secreted in minute quantities into the _______________ which have effects in distant parts of the body
bloodstream
86
Hormones can either be steroid and enter through _____________, or proteins and bind _____________ to produce a second messenger
membranes
receptors
87
Only cells with receptors for that hormone can respond to the _______________
hormone
88
Different receptors have different affinities for a hormone, so depending on the __________, some will respond and others will not
concentration
89
Different cells have different _______________ pathways, so respond differently
transduction
90
Different cell types may not express certain proteins, even if…
stimulated
91
Glycogen breakdown is under the influence of Epinephrine/Adrenaline which is the enzyme responsible for that ____________
breakdown
92
But if Glycogen Phosphorylase is not expressed in the cell there will be no response even if…
stimulated
93
Apoptosis is….
cellular death
94
The death of some cells during development is normal and helps form the ____________ of the body
organs
95
Cells experiencing extensive damage are programmed to die rather than damage other cells and the life of the whole….
organism
96
Intrinsic and Extrinsic signal transduction pathways lead to…
apoptosis
97
Internal damage, such as massive damage to DNA can produce ___________ signals leading to Apoptosis
internal
98
Surface proteins on the _______________ play a key role in this Intrinsic Pathway leading to Apoptosis
Mitochondria
99
________________ signals can also, through a different pathway, promote apoptosis
Extracellular
100
There are death receptors in the ______ ______________ of cells
cell membranes
101
When bound by a signal the death receptor initiates a cellular response leading to a programmed cell…
death
102
Apoptosis usually involves the activation of ______________ which destroy the cytoskeleton and Dnases which destroy the DNA
proteases
