Unit 5- Intracellular Activities Flashcards
1
Q
All internal workings within cells must be _______.
A
Organized
2
Q
What are the methods of organizing the cell?
A
Large, Multi-protein complextes Membrane-Enclosed Organelles
3
Q
Nucleus
A
contains main genome, surrounded by nuclear envelope, nuclear pores facilitate communication between interior of nucleus and cytosol
4
Q
Endoplasmic Reticulum
A
interconnected network of sacs and tubes, continuous with nuclear envelope; site of synthesis of membranes for cell and major site of protein modification (ER lumen)
5
Q
Rough ER
A
has bound ribosomes, nascent proteins are delivered to rER membrane or into ER lumen
6
Q
Smooth ER:
A
no ribosomes, major functions vary between cells types
7
Q
Endocrine cells function:
A
Steroid Hormone Synthesis
8
Q
Liver Cells Function:
A
Detoxification of alcohol and other organics
9
Q
Muscle Cells Function
A
The site of Ca2+ Storage
10
Q
Gogli Apparatus
A
receives proteins and lipids from ER and modifies them, dispatches them to destination
11
Q
Lysosomes
A
degrade worn out organelles (autophagy), macromolecules and engulfed material
12
Q
Endosomes
A
sort and dispatch engulfed material to destination, also may recycle it back to plasma membran
13
Q
Peroxisomes
A
break down lipids and destroy toxic molecules using variety of oxidative reactions
14
Q
Mitochondria
A
Energy synthesis
15
Q
Membranous Organelles are held in place by the _______
A
cytoskeleton: serves as tracks along which organelles move
16
Q
Membranous Organelles are Thought to have evolved in _________ through series of ________.
A
Eukaryotic Ancestor Invaginations
17
Q
Non-membranous organelles treat interior of organelles as ______
A
Exterior
18
Q
The Endomembrane system is composed of:
A
Composed of Nuclear Envelope, ER, Golgi, Lysosomes, Endosomes, Peroxisomes
19
Q
Interiors of ES organelles communicate with each other via ______ that bud from one organelle/plasma membrane and fuse with next organelle or to plasma membrane
A
Vesicles
20
Q
Protein content, both in lumen and membrane proteins, of organelles determines ______
A
Functions
21
Q
Protein sorting occurs by what 3 mechanisms?
A
Through nuclear pores Transported across membranes Transport by vesicles
22
Q
Pritein sorting is controlled by ___ ____ ______ of cargo proteins themselves (____ _____)
A
Amino Acid Sequence Signal sequences
23
Q
Describe Transport through nuclear pores
A
Movement in/out of nucleus Pores penetrate both inner and outer nuclear membranes andfunction as selective gates that actively transport material across
24
Q
Describe Transport across membranes
A
• Movement into ER, Mitochondria, some entry into Peroxisomes • Requires protein translocators, which facilitate movement
25
Describe Transport by vesicles
• Movement from one compartment of ES to next • Requires transport vesicles which carry cargo proteins and pinch off from one membrane and fuse with the next
26
Define: Signal Sequence
stretch of few (4) up to 50 AA in primary sequence of protein that directs protein • Often removed from sorted protein
27
The Nuclear Envelope is double-\_\_\_\_\_\_\_
membraned.
28
Inner Membrane of Nuclear Envelope:
Contains attachmetn sites (proteins) for certain regions of chromosomes and is associated with nuclear lamina
29
nuclear lamina
cage-like network of proteins, give shape to nucleus
30
Outer Membrane of Nuclear Envelope:
continuous with and similar to ER Membrane
31
The nuclear evelope is perforated by ____ \_\_\_\_ which facilitate active entry and exit of large molecules
Nuclear Pores
32
True or False: Small, soluble molecules can freely diffuse through nuclear pores
True
33
Nuclear pores are composed of ___ different proteins
30
34
True or False: Proteins lining pore have large, unstructured regions that form soft, tangled meshwork that prevents large molecules passage but allows small molecules
True
35
Tentacle-like fibrils extend from nuclear pore on the _____ side and failitate entry of approriate large molecules.
Cytosolic
36
Proteins destined for the nucleus are called
Cargo
37
Cargo Proteins contain what signas?
Nuclear Localization Signals (NLS)
38
the NLS is bound by ____ \_\_\_\_\_ _____ in the cytosol
Nuclear Import Receptors
39
Nuclear Import Receptors facilitate interaction within the meshwork of the _____ \_\_\_\_\_\_
Nuclear Pore
40
•Short, repeating AA sequences of non-folded proteins in meshwork interact with _____ \_\_\_\_\_\_ \_\_\_\_\_\_, “bumping” into one protein fiber and the next, making passageway for nuclear import receptor and cargo
Nuclear Import Receptor
41
Once it’s in nucleus, nuclear import receptor binds
Ran-GTP
42
NIR binding to Ran-GTP stimulates what?
NIR to release the cargo
43
Ran-GTP facilitates
Exit from the nucleus
44
In the cytosol, GAP stimulates Ran to hydrolyze
GTP to GDP
45
GAP
GTPase Activating Protein
46
Ran hydrolyzing GTP to GDP does what
Stimulates NIR to release Ran and free the receptor to bind new cargo
47
Proteins destined for the Mitochondria and Chloroplasts have signal sequences where?
N-Terminus
48
The signal sequence on the N-Terminus mediates the interaction with what?
Import Receptors and Organelle Surface
49
(when proteins are destined for mitochondria and chloroplasts) , the import receptor is associated with
The protein translocator
50
Complex of receptor protein translocator, import receptor and signal sequence-containing protein drifts within outer membrane until encountering \_\_\_\_\_\_\_\_\_\_\_in ______ membrane
2nd Protein Translocator Inner
51
When a protein is destined for the Mitochondria and Chloroplasts, the two translocators move the proteins across the membrane, doing what to it in the process?
Unfolding it
52
Once the proteins are across the membrane in the mitochondria and choroplasts, what occurs?
The protein refolds and the signal sequence is removed
53
What are the two methods of peroxisomal import?
From the Cytosol From the ER
54
When proteins are imported to the Peroxisome from the Cytosol, the process requires ___ \_\_\_\_ similar to Mitochondrial Import
Protein Translocators
55
When proteins are imported to the Peroxisome from the Cytosol, are the proteins unfolded like in Mitochondrial import?
No, but their mechanism is unknown
56
When proteins are imported to the Peroxisome from the ER, while the proteins are being translated, they enter the ER and
eventually make their way to peroxisome via vesicles
57
The ER is the entry point for proteins destined for what areas?
ER, other organelles, and outside the cell.
58
Protein entry to ER occurs in (smooth/rough) ER
Rough ER Region
59
Two types of proteins are transported into the nucleus:
Soluble Transmembrane
60
Soluble proteins
Are not attached to the membrane- are completely translocated into the ER Lumen
61
Transmembrane proteins
Partially transported across the membrane and become embedded in it.
62
Protein entry to the ER requires
Signal Recognition Particle (SRP) and SRP Receptor
63
SRP binds ER signal sequence on nascent protein and translating ribosome which does what?
Slows translation
64
SRP Complex binds to what ____ embedded in the Er membrande
SRP Recetor
65
After the SRP recpetor is bound in the ER emembrane, wha occurs?
Translation resumes with the new region of the polypeptide being looped into the ER Lumen nd the signal sequence remaining anchored in the translator
66
Transmembrane Signal ______ cleaves the signal sequence from the completed rotein, releasing it into the ER membrane and Degraded
Peptidase
67
Cleavage results in what?
The release of protein into the lumen.
68
True or False: Transmembrane proteins have start and stop sequences.
True
69
In transmembrane proteins, N-terminal signal sequence gets ______ protein to membrane and then subsequent AA sequences (stop transfer sequence) halt translocation process
Nascent
70
What way does the translocator release proteins into the ER Bilayer?
Sideways
71
Some proteins have internal signal sequences and potentially more than one stop transfer sequences resulting in What?
multi-pass transmembrane proteins
72
In vesicular transport, Cells move soluble proteins and membrane between compartments (organelles) via _____ \_\_\_\_\_, allowing one to communicate with the other
Transport Vesicles
73
In vesicular transport, Progress is from ER to _____ to other organelles and/or ______ \_\_\_\_\_.
Golgi Plasma Membrane
74
only proteins and membrane components needed at destination should be \_\_\_\_\_\_
Transported
75
Coat proteins help form a ____ and help capture molecules to move to correct organelle
Bud
76
What is the function of coat proteins?
help form coated vesicles on parent organelle
77
Clathrin-Coated Vesicles Bud from the _____ and ____ \_\_\_\_
Golgi Plasma Membrane
78
Clathrin is recruited by
Adaptin
79
Adaptin binds specific transmembrane proteins in soon-to-be vesicle, forms a basket-like network that helps form an ______ or ___ which will become the vesicle
Invagination/Pit
80
\_\_\_\_\_\_\_forms a ring around the neck of the pit and eventually pinches it off the membrane
Dynamin
81
True or False: after Dynamin forms the ring, Adaptin and Clathrin bind the vesicle.
False: They release the vesicle
82
Vescicles are actively transported by what type of proteins?
Motor Proteins
83
Although they are transported by motor proteins, vesicles must dock with ____ \_\_\_\_\_.
Target Membrane
84
Rab Proteins:
GTPases bound to surface of vesicle and recognized by tethering protein attached to target membrane
85
GTPase
Are a large family of hydrolase enzymes that can bind and hydrolyze guanosine triphosphate (GTP). The GTP binding and hydrolysis takes place in the highly conserved G domain common to all GTPases.
86
Each organelle and vesicle have unique Rab and ____ proteins
Tethering
87
SNARES
once Rab/tethering protein interaction links vesicle (v) to target (t) membrane, these proteins facilitate docking and membrane fusion
88
vSNARE on vesicle surface interacts/intertwines with _______ on target membrane, providing energy for and driving process of membrane fusion, which is energetically (Favorable/Unfavorable)
tSNARE Unfavorable
89
Signal Transduction:
Conversion of external signal to internal signal
90
Extracellular Signaling Molecule
Molecule used by one cell to stimulate another
91
What are the various mechanisms for cellular communication?
Endocrine (Long Range) Paracrine (Short Range) Synaptic Contact-Dependent
92
Cells respond (or dont) based on what
Receptors they express
93
True or False: Response to same extracellular signaling molecule can vary from cell to cell
True
94
Cell’s overall behavior depends on what?
Signals from other cells
95
Endocrine signals are (long/short range)
Long Range
96
How do steroid hormones transmit their signals?
diffuse through membrane, bind nuclear receptors
97
Paracrine signals are (long/short) range
Short or Local Mediators
98
Dissolved gases transmit their signals by
Diffusing through the membrane, binds to ad regulates specific proteins in a target cell.
99
How do proteins, peptides, amino acids, and nucleotides use extracellular signaling?
bind various cell-surface receptors
100
What are some examples of proteins, peptides, amino acids, and nucleotides using extracellular signaling?
G-protein-coupled receptors (GPCRs), Receptor Tyrosine Kinases (RTKs), ionchannel-coupled receptors
101
Synaptic Extracellular Signaling
Neurotransmitters: bind ion-channel-coupled receptors
102
What is an example of Contact-Dependent Extracellular Signaling?
Various • Example: Glycoproteins from one cell bind leptins on another
103
Steroid hormones are ____ (Lipid-Based) and (passs/cannot pass) directly though membrane
Hydrophobic Easily pass
104
Steroid Hormone Singlaing: In cytosol or nucleus, hormone binds _____ \_\_\_\_\_\_\_, changing receptor’s conformation such that it now binds DNA and regulates transcription
Nuclear Receptors
105
True or False: NO (nitric oxide) cannot pass directly through membrane of cells
False: Nitric Oxide passes directly through the membrane.
106
Nitric Oxide works only locally. Why?
because it easily interacts with O2 and H2O, which are abundant, resulting in loss of activity
107
Nitric Oxide is produced by what type of cells?
endothelial cells that line blood vessels and stimulates smooth muscle cells (SMCs) in vessel walls
108
Nitric Oxide binds and activates ______ \_\_\_\_\_\_, which produces cGMP which through its own set of activities stimulates relaxation of SMC
Guanylyl Cyclase
109
What are cell-Surface Receptors?
Transmembrane receptors that take message from outside of cell and convert it into an internal signal of a different form
110
Upon Binding by ligands, cell-surface receptor proteins initate what?
intracellular signaling process(es) where message is passed “downstream” from one intracellular signaling molecule to another • Functions and results of intracellular signaling pathways vary
111
What are the various types of Cell-Surface Receptors?
GPCRs RTKs
112
What is a GPCR
G-Protein Coupled Receptor
113
True or False: There are only 3 trypes of GPCRs
False: There are over a thousand different types of GPCRs.
114
The seven-pass transmembrane protein functions as what?
functions as receptor • When activated, binds and activates accessory G-proteins (G = GTPase), alpha & beta-Gamma
115
Before activation, GPCR and G Proteins are \_\_\_\_, may or may not be associated prior to activation
Inactive
116
Upon Ligand binding, ____ conformation changes, which in turn alters G-Protein's conformation
GPCR's
117
Aleration of the Alpha subnit of the G-Protein does what?
Allows for exchange of bound GDP for GTP, activating the Alpha and Beta-Gamma Subunits
118
Activated Alpha and Beta-Gamma subunits may or may not ____ befre interacting with tragets/effector proteins.
Dissociate
119
In the G-Protein inactivation, what controls the duration of the response?
The Alpha Subunit
120
The Aplha subunit eventually hydrolyzes What into What in G Protein Inactivation?
GTP to GDP, inactivating the Aphla Subunit.
121
in G Protein inactivation, the Aplha subunit binds active ___ \_\_\_\_ , resulting in that subunut's inactivation.
Beta-Gamma
122
When both subunits are inavtivaed in G-Protein inavtibation, they are raeasdy for what?
Re-Activation
123
What toxins work by impacting the duration of Alpha Subunit Activity?
Pertussis, Cholera
124
G Proteins vary depending on type of _____ \_\_\_\_\_ they activate, which often produce secondary messengers that impact other cellular components
Effector Proteins
125
What are the types of G-Proteins
Ion-channel activating • Gs • Gi • Gq
126
Gs activates
activates adenylyl cyclase whichconverts ATP to cAMP
127
Gi function:
Inhibits Adenylyl Cylcase
128
Gq Function:
activates Phospholipase C which generates inositol triphosphate (IP3) and diacylglycerol (DAG), both of which function as secondary messengers
129
IP3
Inositol Triphosphate
130
Diaglycerol
DAG
131
phosphodiesterase
comverts Camp into AMP
132
Camp is produced by
Adenylyl Cylcase
133
Camp activates what?
cAMP-dependent protein kinase (aka PKA)
134
PKA phosphorylates various _____ and _____ AAs in various proteins resulting in activation or deactivation.
Serines Theronines
135
In Gq-mediated activation of Protein Kinase C , activated Gq activates what?
PLC/Phospholipase C
136
Phospholpiase C produces ______ and souble IP3
Diaglycerol (DAG)
137
IP3 diffuses Ligand-gated ___ channels in the ER membrane , opening them.
Ca2+ Binds Protein Kinase C (PKC)
138
In Gq-mediated activation of Protein Kinase C , DAG binds \_\_\_.
PKC
139
In Gq-mediated activation of PKC, the Combination of Ca2+ and DAG binding PKC (activates/Inactivates) PKC
Activates
140
Active PKC has similar (in terms of variety) activities to activated \_\_\_\_.
PKA
141
Enzyme-coupled Receptors
Transmembrane receptors that have enzymatic activity associated with intracellular regions OR that associate with enzymes upon activation
142
What are the types of Enzyme-Coupled Receptors' responses?
Slow(Hours) Rapid
143
Slow ECR responses?
responses that often involve changes in gene expression • Signaling molecules causing this type of response are often growth factors
144
Rapid ECR Repsonse
responses that alter cytoskeleton and potentially cell movement • Signaling molecules causing this type of response are often attached to ECM
145
What is a common type of Enzyme-Coupled Receptor?
Receptor Tyrosine Kinase (RTK)
146
Ras
Small, membrane-bound, monomeric GTPase that is activated by all RTKs
147
Ras is active when has _____ bound, eventually hydrolyzes GTP to \_\_\_\_, inactivating it (similar to Ga)
GTP
148
Ras-Guanine Exchange Factor (Ras-GEF)
Ras-Guanine Exchange Factor (Ras-GEF) stimulates exchange of GDP for GTP • Active RTK recruits and activates Ras-GEF, resulting in Ras activation
149
• Ras-GTPase-activating Protein (Ras-GAP)
stimulates GTPase activity of Ras
150
Activated Ras results in several Serine/Threonine phosphorylation events which helps ?
send signal from RTK to nucleus
151
MAP
mitogen-activated protein
152
MAP-Kinase is what type of molecule?
Signaling
153
Ras activates
MAP Kinase Kinase Kinase
154
MAP Kinase Kinase Kinase activates
MAP Kinase Kinase
155
MAP Kinase Kinase activates
MAP Kinase
156
MAP Kinase Activates
several transcription factors associated with proliferation
157
RTKs may aso activate
PI3K
158
PI3K Phosphorylates
inositol-lipids in plasma membrane
159
True Or False: PI3K phosphorylates inositol-lipids in plasma membrane which creates docking sites for various signaling proteins that can activate each other now that they’ve been recruited to membrane
TRUE
160
AKT is also kown as
PKB
161
AKT/PKB has various targets with overall effect of promoting cell survival:
Bad TOR
162
BAd
protein that promotes cellular suicide. PKB inactivates Bad.
163
PKB inactivates
Bad
164
Tor
protein that enhances protein synthesis and inhibits protein destruction, ultimate result of which is promotion of cell survival and growth
165
GPCRs and RTKS
Both types of receptors activate myriad of pathways that may directly or indirectly impact each other
