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Cell Biology 2203 > Unit 5- Intracellular Activities > Flashcards

Unit 5- Intracellular Activities Flashcards

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1
Q

All internal workings within cells must be _______.

A

Organized

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2
Q

What are the methods of organizing the cell?

A

Large, Multi-protein complextes Membrane-Enclosed Organelles

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3
Q

Nucleus

A

contains main genome, surrounded by nuclear envelope, nuclear pores facilitate communication between interior of nucleus and cytosol

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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)

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5
Q

Rough ER

A

has bound ribosomes, nascent proteins are delivered to rER membrane or into ER lumen

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6
Q

Smooth ER:

A

no ribosomes, major functions vary between cells types

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7
Q

Endocrine cells function:

A

Steroid Hormone Synthesis

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8
Q

Liver Cells Function:

A

Detoxification of alcohol and other organics

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9
Q

Muscle Cells Function

A

The site of Ca2+ Storage

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10
Q

Gogli Apparatus

A

receives proteins and lipids from ER and modifies them, dispatches them to destination

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11
Q

Lysosomes

A

degrade worn out organelles (autophagy), macromolecules and engulfed material

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12
Q

Endosomes

A

sort and dispatch engulfed material to destination, also may recycle it back to plasma membran

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13
Q

Peroxisomes

A

break down lipids and destroy toxic molecules using variety of oxidative reactions

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14
Q

Mitochondria

A

Energy synthesis

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15
Q

Membranous Organelles are held in place by the _______

A

cytoskeleton: serves as tracks along which organelles move

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16
Q

Membranous Organelles are Thought to have evolved in _________ through series of ________.

A

Eukaryotic Ancestor Invaginations

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17
Q

Non-membranous organelles treat interior of organelles as ______

A

Exterior

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18
Q

The Endomembrane system is composed of:

A

Composed of Nuclear Envelope, ER, Golgi, Lysosomes, Endosomes, Peroxisomes

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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

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20
Q

Protein content, both in lumen and membrane proteins, of organelles determines ______

A

Functions

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21
Q

Protein sorting occurs by what 3 mechanisms?

A

Through nuclear pores Transported across membranes Transport by vesicles

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22
Q

Pritein sorting is controlled by ___ ____ ______ of cargo proteins themselves (____ _____)

A

Amino Acid Sequence Signal sequences

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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

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24
Q

Describe Transport across membranes

A

• Movement into ER, Mitochondria, some entry into Peroxisomes • Requires protein translocators, which facilitate movement

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25
Q

Describe Transport by vesicles

A

• 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

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26
Q

Define: Signal Sequence

A

stretch of few (4) up to 50 AA in primary sequence of protein that directs protein • Often removed from sorted protein

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27
Q

The Nuclear Envelope is double-_______

A

membraned.

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28
Q

Inner Membrane of Nuclear Envelope:

A

Contains attachmetn sites (proteins) for certain regions of chromosomes and is associated with nuclear lamina

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29
Q

nuclear lamina

A

cage-like network of proteins, give shape to nucleus

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30
Q

Outer Membrane of Nuclear Envelope:

A

continuous with and similar to ER Membrane

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31
Q

The nuclear evelope is perforated by ____ ____ which facilitate active entry and exit of large molecules

A

Nuclear Pores

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32
Q

True or False: Small, soluble molecules can freely diffuse through nuclear pores

A

True

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33
Q

Nuclear pores are composed of ___ different proteins

A

30

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34
Q

True or False: Proteins lining pore have large, unstructured regions that form soft, tangled meshwork that prevents large molecules passage but allows small molecules

A

True

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35
Q

Tentacle-like fibrils extend from nuclear pore on the _____ side and failitate entry of approriate large molecules.

A

Cytosolic

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36
Q

Proteins destined for the nucleus are called

A

Cargo

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37
Q

Cargo Proteins contain what signas?

A

Nuclear Localization Signals (NLS)

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38
Q

the NLS is bound by ____ _____ _____ in the cytosol

A

Nuclear Import Receptors

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39
Q

Nuclear Import Receptors facilitate interaction within the meshwork of the _____ ______

A

Nuclear Pore

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40
Q

•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

A

Nuclear Import Receptor

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41
Q

Once it’s in nucleus, nuclear import receptor binds

A

Ran-GTP

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42
Q

NIR binding to Ran-GTP stimulates what?

A

NIR to release the cargo

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43
Q

Ran-GTP facilitates

A

Exit from the nucleus

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44
Q

In the cytosol, GAP stimulates Ran to hydrolyze

A

GTP to GDP

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45
Q

GAP

A

GTPase Activating Protein

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46
Q

Ran hydrolyzing GTP to GDP does what

A

Stimulates NIR to release Ran and free the receptor to bind new cargo

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47
Q

Proteins destined for the Mitochondria and Chloroplasts have signal sequences where?

A

N-Terminus

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48
Q

The signal sequence on the N-Terminus mediates the interaction with what?

A

Import Receptors and Organelle Surface

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49
Q

(when proteins are destined for mitochondria and chloroplasts) , the import receptor is associated with

A

The protein translocator

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50
Q

Complex of receptor protein translocator, import receptor and signal sequence-containing protein drifts within outer membrane until encountering ___________in ______ membrane

A

2nd Protein Translocator Inner

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51
Q

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?

A

Unfolding it

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52
Q

Once the proteins are across the membrane in the mitochondria and choroplasts, what occurs?

A

The protein refolds and the signal sequence is removed

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53
Q

What are the two methods of peroxisomal import?

A

From the Cytosol From the ER

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54
Q

When proteins are imported to the Peroxisome from the Cytosol, the process requires ___ ____ similar to Mitochondrial Import

A

Protein Translocators

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55
Q

When proteins are imported to the Peroxisome from the Cytosol, are the proteins unfolded like in Mitochondrial import?

A

No, but their mechanism is unknown

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56
Q

When proteins are imported to the Peroxisome from the ER, while the proteins are being translated, they enter the ER and

A

eventually make their way to peroxisome via vesicles

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57
Q

The ER is the entry point for proteins destined for what areas?

A

ER, other organelles, and outside the cell.

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58
Q

Protein entry to ER occurs in (smooth/rough) ER

A

Rough ER Region

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59
Q

Two types of proteins are transported into the nucleus:

A

Soluble Transmembrane

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60
Q

Soluble proteins

A

Are not attached to the membrane- are completely translocated into the ER Lumen

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61
Q

Transmembrane proteins

A

Partially transported across the membrane and become embedded in it.

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62
Q

Protein entry to the ER requires

A

Signal Recognition Particle (SRP) and SRP Receptor

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63
Q

SRP binds ER signal sequence on nascent protein and translating ribosome which does what?

A

Slows translation

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64
Q

SRP Complex binds to what ____ embedded in the Er membrande

A

SRP Recetor

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65
Q

After the SRP recpetor is bound in the ER emembrane, wha occurs?

A

Translation resumes with the new region of the polypeptide being looped into the ER Lumen nd the signal sequence remaining anchored in the translator

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66
Q

Transmembrane Signal ______ cleaves the signal sequence from the completed rotein, releasing it into the ER membrane and Degraded

A

Peptidase

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67
Q

Cleavage results in what?

A

The release of protein into the lumen.

68
Q

True or False: Transmembrane proteins have start and stop sequences.

A

True

69
Q

In transmembrane proteins, N-terminal signal sequence gets ______ protein to membrane and then subsequent AA sequences (stop transfer sequence) halt translocation process

A

Nascent

70
Q

What way does the translocator release proteins into the ER Bilayer?

A

Sideways

71
Q

Some proteins have internal signal sequences and potentially more than one stop transfer sequences resulting in What?

A

multi-pass transmembrane proteins

72
Q

In vesicular transport, Cells move soluble proteins and membrane between compartments (organelles) via _____ _____, allowing one to communicate with the other

A

Transport Vesicles

73
Q

In vesicular transport, Progress is from ER to _____ to other organelles and/or ______ _____.

A

Golgi Plasma Membrane

74
Q

only proteins and membrane components needed at destination should be ______

A

Transported

75
Q

Coat proteins help form a ____ and help capture molecules to move to correct organelle

A

Bud

76
Q

What is the function of coat proteins?

A

help form coated vesicles on parent organelle

77
Q

Clathrin-Coated Vesicles Bud from the _____ and ____ ____

A

Golgi Plasma Membrane

78
Q

Clathrin is recruited by

A

Adaptin

79
Q

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

A

Invagination/Pit

80
Q

_______forms a ring around the neck of the pit and eventually pinches it off the membrane

A

Dynamin

81
Q

True or False: after Dynamin forms the ring, Adaptin and Clathrin bind the vesicle.

A

False: They release the vesicle

82
Q

Vescicles are actively transported by what type of proteins?

A

Motor Proteins

83
Q

Although they are transported by motor proteins, vesicles must dock with ____ _____.

A

Target Membrane

84
Q

Rab Proteins:

A

GTPases bound to surface of vesicle and recognized by tethering protein attached to target membrane

85
Q

GTPase

A

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
Q

Each organelle and vesicle have unique Rab and ____ proteins

A

Tethering

87
Q

SNARES

A

once Rab/tethering protein interaction links vesicle (v) to target (t) membrane, these proteins facilitate docking and membrane fusion

88
Q

vSNARE on vesicle surface interacts/intertwines with _______ on target membrane, providing energy for and driving process of membrane fusion, which is energetically (Favorable/Unfavorable)

A

tSNARE Unfavorable

89
Q

Signal Transduction:

A

Conversion of external signal to internal signal

90
Q

Extracellular Signaling Molecule

A

Molecule used by one cell to stimulate another

91
Q

What are the various mechanisms for cellular communication?

A

Endocrine (Long Range) Paracrine (Short Range) Synaptic Contact-Dependent

92
Q

Cells respond (or dont) based on what

A

Receptors they express

93
Q

True or False: Response to same extracellular signaling molecule can vary from cell to cell

A

True

94
Q

Cell’s overall behavior depends on what?

A

Signals from other cells

95
Q

Endocrine signals are (long/short range)

A

Long Range

96
Q

How do steroid hormones transmit their signals?

A

diffuse through membrane, bind nuclear receptors

97
Q

Paracrine signals are (long/short) range

A

Short or Local Mediators

98
Q

Dissolved gases transmit their signals by

A

Diffusing through the membrane, binds to ad regulates specific proteins in a target cell.

99
Q

How do proteins, peptides, amino acids, and nucleotides use extracellular signaling?

A

bind various cell-surface receptors

100
Q

What are some examples of proteins, peptides, amino acids, and nucleotides using extracellular signaling?

A

G-protein-coupled receptors (GPCRs), Receptor Tyrosine Kinases (RTKs), ionchannel-coupled receptors

101
Q

Synaptic Extracellular Signaling

A

Neurotransmitters: bind ion-channel-coupled receptors

102
Q

What is an example of Contact-Dependent Extracellular Signaling?

A

Various • Example: Glycoproteins from one cell bind leptins on another

103
Q

Steroid hormones are ____ (Lipid-Based) and (passs/cannot pass) directly though membrane

A

Hydrophobic Easily pass

104
Q

Steroid Hormone Singlaing: In cytosol or nucleus, hormone binds _____ _______, changing receptor’s conformation such that it now binds DNA and regulates transcription

A

Nuclear Receptors

105
Q

True or False: NO (nitric oxide) cannot pass directly through membrane of cells

A

False: Nitric Oxide passes directly through the membrane.

106
Q

Nitric Oxide works only locally. Why?

A

because it easily interacts with O2 and H2O, which are abundant, resulting in loss of activity

107
Q

Nitric Oxide is produced by what type of cells?

A

endothelial cells that line blood vessels and stimulates smooth muscle cells (SMCs) in vessel walls

108
Q

Nitric Oxide binds and activates ______ ______, which produces cGMP which through its own set of activities stimulates relaxation of SMC

A

Guanylyl Cyclase

109
Q

What are cell-Surface Receptors?

A

Transmembrane receptors that take message from outside of cell and convert it into an internal signal of a different form

110
Q

Upon Binding by ligands, cell-surface receptor proteins initate what?

A

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
Q

What are the various types of Cell-Surface Receptors?

A

GPCRs RTKs

112
Q

What is a GPCR

A

G-Protein Coupled Receptor

113
Q

True or False: There are only 3 trypes of GPCRs

A

False: There are over a thousand different types of GPCRs.

114
Q

The seven-pass transmembrane protein functions as what?

A

functions as receptor • When activated, binds and activates accessory G-proteins (G = GTPase), alpha & beta-Gamma

115
Q

Before activation, GPCR and G Proteins are ____, may or may not be associated prior to activation

A

Inactive

116
Q

Upon Ligand binding, ____ conformation changes, which in turn alters G-Protein’s conformation

A

GPCR’s

117
Q

Aleration of the Alpha subnit of the G-Protein does what?

A

Allows for exchange of bound GDP for GTP, activating the Alpha and Beta-Gamma Subunits

118
Q

Activated Alpha and Beta-Gamma subunits may or may not ____ befre interacting with tragets/effector proteins.

A

Dissociate

119
Q

In the G-Protein inactivation, what controls the duration of the response?

A

The Alpha Subunit

120
Q

The Aplha subunit eventually hydrolyzes What into What in G Protein Inactivation?

A

GTP to GDP, inactivating the Aphla Subunit.

121
Q

in G Protein inactivation, the Aplha subunit binds active ___ ____ , resulting in that subunut’s inactivation.

A

Beta-Gamma

122
Q

When both subunits are inavtivaed in G-Protein inavtibation, they are raeasdy for what?

A

Re-Activation

123
Q

What toxins work by impacting the duration of Alpha Subunit Activity?

A

Pertussis, Cholera

124
Q

G Proteins vary depending on type of _____ _____ they activate, which often produce secondary messengers that impact other cellular components

A

Effector Proteins

125
Q

What are the types of G-Proteins

A

Ion-channel activating • Gs • Gi • Gq

126
Q

Gs activates

A

activates adenylyl cyclase whichconverts ATP to cAMP

127
Q

Gi function:

A

Inhibits Adenylyl Cylcase

128
Q

Gq Function:

A

activates Phospholipase C which generates inositol triphosphate (IP3) and diacylglycerol (DAG), both of which function as secondary messengers

129
Q

IP3

A

Inositol Triphosphate

130
Q

Diaglycerol

A

DAG

131
Q

phosphodiesterase

A

comverts Camp into AMP

132
Q

Camp is produced by

A

Adenylyl Cylcase

133
Q

Camp activates what?

A

cAMP-dependent protein kinase (aka PKA)

134
Q

PKA phosphorylates various _____ and _____ AAs in various proteins resulting in activation or deactivation.

A

Serines Theronines

135
Q

In Gq-mediated activation of Protein Kinase C , activated Gq activates what?

A

PLC/Phospholipase C

136
Q

Phospholpiase C produces ______ and souble IP3

A

Diaglycerol (DAG)

137
Q

IP3 diffuses Ligand-gated ___ channels in the ER membrane , opening them.

A

Ca2+ Binds Protein Kinase C (PKC)

138
Q

In Gq-mediated activation of Protein Kinase C , DAG binds ___.

A

PKC

139
Q

In Gq-mediated activation of PKC, the Combination of Ca2+ and DAG binding PKC (activates/Inactivates) PKC

A

Activates

140
Q

Active PKC has similar (in terms of variety) activities to activated ____.

A

PKA

141
Q

Enzyme-coupled Receptors

A

Transmembrane receptors that have enzymatic activity associated with intracellular regions OR that associate with enzymes upon activation

142
Q

What are the types of Enzyme-Coupled Receptors’ responses?

A

Slow(Hours) Rapid

143
Q

Slow ECR responses?

A

responses that often involve changes in gene expression • Signaling molecules causing this type of response are often growth factors

144
Q

Rapid ECR Repsonse

A

responses that alter cytoskeleton and potentially cell movement • Signaling molecules causing this type of response are often attached to ECM

145
Q

What is a common type of Enzyme-Coupled Receptor?

A

Receptor Tyrosine Kinase (RTK)

146
Q

Ras

A

Small, membrane-bound, monomeric GTPase that is activated by all RTKs

147
Q

Ras is active when has _____ bound, eventually hydrolyzes GTP to ____, inactivating it (similar to Ga)

A

GTP

148
Q

Ras-Guanine Exchange Factor (Ras-GEF)

A

Ras-Guanine Exchange Factor (Ras-GEF) stimulates exchange of GDP for GTP • Active RTK recruits and activates Ras-GEF, resulting in Ras activation

149
Q

• Ras-GTPase-activating Protein (Ras-GAP)

A

stimulates GTPase activity of Ras

150
Q

Activated Ras results in several Serine/Threonine phosphorylation events which helps ?

A

send signal from RTK to nucleus

151
Q

MAP

A

mitogen-activated protein

152
Q

MAP-Kinase is what type of molecule?

A

Signaling

153
Q

Ras activates

A

MAP Kinase Kinase Kinase

154
Q

MAP Kinase Kinase Kinase activates

A

MAP Kinase Kinase

155
Q

MAP Kinase Kinase activates

A

MAP Kinase

156
Q

MAP Kinase Activates

A

several transcription factors associated with proliferation

157
Q

RTKs may aso activate

A

PI3K

158
Q

PI3K Phosphorylates

A

inositol-lipids in plasma membrane

159
Q

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

A

TRUE

160
Q

AKT is also kown as

A

PKB

161
Q

AKT/PKB has various targets with overall effect of promoting cell survival:

A

Bad TOR

162
Q

BAd

A

protein that promotes cellular suicide. PKB inactivates Bad.

163
Q

PKB inactivates

A

Bad

164
Q

Tor

A

protein that enhances protein synthesis and inhibits protein destruction, ultimate result of which is promotion of cell survival and growth

165
Q

GPCRs and RTKS

A

Both types of receptors activate myriad of pathways that may directly or indirectly impact each other

Cell Biology 2203 (5 decks)

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