Exam 3 Flashcards
1
Q
What are the tubular membranes in the ER called?
A
Flattened sacks
Cisternae
2
Q
What is the space called within the ER lumen?
A
Cisternal Space
3
Q
List the two types of ER
A
Rough
Smooth
4
Q
Is the smooth ER associated with synthesis?
A
No
5
Q
Where are the proteins made by the RER destined?
A
Secretion or membrane bound proteins
6
Q
Which side are the ribosomes attached to on the RER?
A
Cytosolic side
7
Q
Is the rRNA charge positive or negative in the RER?
A
Negative
8
Q
Where do the proteins destined for secretion go after the RER?
A
Golgi
9
Q
Proteins made by the RER ribosomes are generally imported into the RER cisternal space by a process known as…..
A
Cotranslational Import
10
Q
How are the proteins made by the RER transported to the cisternal space?
A
Translocon
11
Q
What are the 3 different protein signal sequences?
A
ERSS
Internal Stop transfer sequence
Internal Start transfer Sequence
12
Q
Where does the ERSS direct import?
A
Translation of the ribosome
N-terminal
13
Q
Once the ERSS is made where does the ribosome dock?
A
Translocon via SRP and temporarily blocks translation
14
Q
What is the job of SRP
A
Direct to translocon
15
Q
Which side of the ERSS protein is cleaved off?
A
N terminus
16
Q
List the steps of cotranslational import
A
SRP binds to ERSS SRP takes polypeptide to translocon Dock GTPs bind to SRP and unblocks translation GTP to GDP release SRP ERSS is cleaved off (N terminus) C terminus leads polypeptide to ER lumen
17
Q
What does insulin regulate?
A
Blood glucose levels
18
Q
Where is n-linked
A
RER
19
Q
Where is o-linked?
A
Golgi
20
Q
What is the job of the Internal Stop Transfer
A
To stop the translocation at the site. iN and C cytosol
21
Q
What is the job of the internal Start Transfer?
A
Signals SRP to dock with the translocon
22
Q
What is the main job of the Smooth ER?
A
Drug detox
Cabohydrate metabolism
Calcium storage
Hormone biosynthesis
23
Q
What is the Golgi involved in?
A
Processing and Packaging
24
Q
How many cisternae does the Golgi have?
A
3-8
25
What are the two sides of the Golgi?
Cis- forming
| Trans- maturing
26
What is the Cis Golgi closest to?
RER
27
Define compartmentalization.
Processing enzymes in the intracisternal space of the golgi
28
What are the two models for material flow through the Golgi?
Stationary model and Maturation model
29
What is the most supported model of material flow in the Golgi?
Maturation model
30
What is the ERGIC tubulovesicular structure?
The space between the Golgi and the ER
31
Which way do materials move in the Golgi?
CGN toward TGN
32
All known Golgi-specific proteins are ______ proteins many with just a single transmembrane domain.
Integral membrane
33
What are the 3 main fates for transport vesicles from the Golgi?
Secretory vesicles, endosomes (lysosomes) or retrograde transport
34
What is the function of the lysosome?
digestion
35
How does a lysosome form?
Endocytic vesicles and early endosomes
Late endosomes
Mature lysosome due to pH lowering in lumen
V pump
36
Protein modification in the RER
N linked to asparagine
37
Protein modification in the golgi
O linked to serine and threonine
38
What does protein sorting depend on?
Sequence tags
| Transmembrane domain length
39
Constitutive secretion
continuous secretion, unregulated
40
Regulated secretion
concentration of materials in the vesicle
| ex insulin
41
What is a specific example of a protein destined for the regulated secretion pathway. Hint: glucose balance
GLUT 4
42
Where is GLUT 4 synthesized?
RER
43
What are the two main mechanisms for cell signaling?
Electrical and Chemical
44
Which system utilizes electrical signals?
Nervous system
45
What are the two main categories of cells in the nervous system?
Neurons and Glial cells
46
Define membrane potential
An unequal distribution of ions across a cellular membrane.
47
Vm
| inside with respect to outside of the cell
Quantitative electrical difference across the membrane
48
What are the three ions that membrane potential relies on?
Na, K, Cl
49
Electroneutrality
The charged particles can be separated
50
How many of each ion does the Na/K pump out/in?
3 Na out 2 K in
51
Equilibrium potential
The voltage difference across the membrane
52
What is the resting membrane potential for mammals
~-70--80
53
At rest, is the membrane polarized or depolarized?
Polarized
54
Graded potentials
A signal that is of varying magnitude
55
True or False. Graded potentials dissipate with distance along a membrane and time
TRUE
56
Action potential
an all or nothing response. magnitude invariable
57
Does action potential dissipate as it travels along the membrane?
No
58
What causes changes in permeability of the cell membrane?
Opening or closing of some ion channel
59
Integral membrane proteins that form ion-conducting pores across the membrane are_________
gated
60
Ligand-gated
Will open in response to binding of ligand
61
Voltage gated
Will open in response to a change in membrane potential
62
What mechanism is used in the Inactivation gate?
Ball and Chain
63
What are action potentials?
Large electrical depolarizations and repolarizations of the plasma membrane
64
Which channels are involved in the action potentials?
K and Na
65
AP depolarization
Opening of Na channels
Positive inside
Approaches E na
66
AP repolarization
Opening of K channels
Negative inside
Towards Ek
67
AP hyperpolarization
undershoot due to prolonged opening of K channels
68
What is required in order for AP to occur?
Threshold must be met
69
What is the resting potential for the Na/K gate?
-60mV
70
What causes the absolute refractory period?
Na channel inactivation
71
When can the Na diffuse into the cell for the depolarization period?
Once the cell is depolarized to threshold
72
When does repolarization occur?
When K diffuses out
73
Hyperpolarization
When K continues to flow out, overcorrection
74
Subthreshold depolarization
Depolarization does not reach threshold
75
Does the membrane potential ever reach the Ena?
NO!
76
Why can no stimulus cause another action potential in the absolute refractory period?
The na channels cant be opened
77
What is relative refractory period
Inactivation gate is opened for Na during repolarization and beginning of hyperpolarization
78
What causes the gates to open and close?
Initial depolarization to threshold
79
When is deinactivation?
-40 - -80 during repolarization
80
During repolarization are the Na channels inactivated or closed?
Inactivated
81
What is the period called when the Na channels are inactivated?
Refractory period
82
Can an AP occur in the relative refractory period?
Yes but it is more difficult
83
True or false
| The refractory period prevents APs from occurring too close together in time. APs cannot summate
TRUE
84
How do APs travel on the axon?
Down from the point of origin and spread passively
85
What is electrotonic or passive spread?
The magnitude of the initial depolarization is lower at sites distant from the initial site
86
What does lambda represent?
Space that it takes for the voltage to decay to 37%
87
Is passive electrotonic spread of the depolarization AP conduction?
NO
88
________ Spread passively to surrounding regions
Depolarizations
89
Which direction does passive spread occur?
All directions
90
Anatomy of myelinated axon
multiple intermittently spaced sheaths of membranes wrapped around the axon
91
Myelinated axon
Sheaths that are wrapped around the axon
92
What are the gaps between the sheaths called?
Nodes of Ranvier
93
Myelination allows for more _______ conduction velocities.
Rapid
94
Which provides faster dispersal?
Myelinated is faster
95
How is the electrical signal transmitted from cell to cell?
Synapses
| post and pre
96
How many neurotransmitters does each presynaptic cell have?
One main
97
Depolarization=Excitatory
Excitatory post synaptic potential
98
Hyperpolarization=inhibitory
Inhibitory postsynaptic potential
99
(Pre or post synaptic cell?)
| AP causes voltage gated Ca channels in the membrane to open at the terminal bulb
Pre synaptic
100
Pre or post synaptic?
Ca 2+ diffuses into the cell and causes synaptic vesicles to fuse to the presynaptic membrane
Neurotransmitter is released into the cleft
Pre synaptic
101
Pre or post synaptic?
| Neurotransmitter binds to its receptor
Post synaptic
102
Pre or post synaptic?
| Induces a change in membrane conductance (ESPS or IPSP which are graded potentials)
Post synaptic
103
What mechanism is used to fuse the synaptic vesicles and the presynaptic membrane?
Ca 2+ induced exocytosis
104
What are the three main vesicles present in the terminal bulb?
Undocked
Docked
Docked and primed
105
On the vesicle there are V snares and synaptotagmin
Found in the vesicle
106
True or false
| Docking proteins are tethering proteins
True
107
What does priming involve?
Interactions of v-snares and t-snares
108
What are toxins that interfere with vesicle release?
Botox, tetanus and presynaptic blockers
109
Ionotropic
The receptor is the channel
110
Metabotropic
The receptor communicates with a channel indirectly
111
Ionotropic receptor example
nachr opens the Na+ channel
112
Ionotropic receptor example
GABAa opens the Cl- channel
113
Metabotropic Receptor example
GABAb leads to opening of K channels, hyperpolarization
114
Are postsynaptic potentials additive?
Yes! Time and space
115
How can the activation state of the postsynaptic cell be determined?
Net influence of all the excitatory and inhibitory influences
116
What type of potentials are the incoming electrical signals at the dendrites and soma?
Graded IPSP and EPSP
117
Do IPSP and EPSP potentials degrade with time?
Yes
118
Why can't the dendrites or soma fire APs?
Because of the channel types that they are.
119
Can neurotransmitters be removed from the synapse by transport into the cells?
Yes
120
True or False
| All neurotransmitters are simply degraded like Ach.
False
