1
Q
Classes of membrane proteins
A
- Integral
- Peripheral
- Lipid Anchored
2
Q
Examples of Integral Membrane proteins
A
- Transmembrane protein: Spans from extracellular to intracellular side
- Protein that only spans through one leaflet
3
Q
Peripheral Proteins
A
- Not inserted within the bilayer
- Can exist in the cytosolic or extracellular space
4
Q
Function of Integral proteins
A
- Receptors
- Channels
- Transporters
- Amphipathic (Hydrophobic and Hydrophilic regions)
- Hydrophobic region is asspociated with the fatty acid region
- Not Fixed and can be moved
5
Q
Interactions in the transmembrane doman of integral proteins
A
- Van der waals drives the hydrophobic interactions with the associated fatty acids within the membrane
6
Q
How do peripheral proteins increact with the membrane
A
- Weak non-covalent bonds like van der waals
- Dynamic relationship with membrane : Enzymes and factors that transmit transmembrane signals
7
Q
How are lipid anchored proteins bonded with the membrane
A
- Covalently bonded lipid group located within the membrane
- Can be either intracellular or extracellular
8
Q
Glycocalyx
A
- Membrane carbohydrates
- Located extracellularly
- Short
- Can interact to lipid component of the protein component
- Provides physical barrier
- Provides a way to interact with the extracellular matrix
- Provides lubrication around the cell for cell mobility
- Provides variablity
9
Q
how is CHO linked to protein
A
Covalently
10
Q
Process of covalently attaching CHO to protein is called
A
Glycosylation
11
Q
Where do majority of CHO bind to
A
Protein
12
Q
How do CHO bond to lipid
A
Covalently by glycosidic bonds
13
Q
2 types of linkages between CHO and proteins
A
- N - Linkages
- O - Linkages
14
Q
Which AA make N - Linkages
A
- Aspargine
- Arginine
15
Q
Which AA make O linkages
A
- Serine
- Threonine
16
Q
Parts of plasma membrane structure
A
- Cell Cortex
- Spectrin
17
Q
Spectrin
A
- Fibular protein
- Primary protein for internal membrane skeleton
17
Q
Cell Cortex
A
- Only in animal cells
- Protection and structural integrity
18
Q
Major component of internal membrane skeleton
A
Spectrin
19
Q
Spectrin is attached to membrane surface via _______
A
Ankyrin
20
Q
Factors influencing membane fluidity
A
- Temperature
- Cholestrol
- Saturated and Unsaturated fattt acids
21
Q
When temp is cold
A
- Rigid
- Not as fluid
- May break
22
Q
When temp is hot
A
- Too fluid / flexible
- Wont hold shape
23
Q
Saturated fatty acids
A
More rigid
Tight packing
24
Unsaturated fatty acids
- Have more kinks
- More fluidity
25
Phospholipids can move ______
Laterally
26
Cell fusion
Technique whereby two different types of cellls, or cells from two different species, can be fused to produce one cell
27
What reveals the mobility of membrane proteins
Cell fusion
28
Protein movement is slower when
Protein size
Membrane viscocity
29
Which interactions limit protein movement
- Membrane skeleton
- Neighbouring proteins
- Extracellular interactions
30
Membranes vary in protein
- Composition
- Mobility
31
Intestinal / kidney epithelial cells are
Highly polarized
32
Apical membane
Absorbtion
33
Basal membrane
- Generation of ion gradients
- basement membrane contact
34
Lateral
Cell contact / communications
35
Movement of substances across cell membrane is
Selectively Permeable
36
Permeability factors
- Molecular size
- Lipid solubility
37
High concentration of ions in the intracellular space
- Pottasium
- Organic anions
38
High concentration of ions in the extracellular space
- Sodium
- Chloride
39
Two types of transport
- Passive
- Active
40
Types of passive transport
- Diffusion
- Channel Protein
- Carrier protein
- Goes along the concentration gradient
41
Fascilitated diffusion
- Channel Protein
- Carrier Protein
42
Active Transport
Against Concentration gradient
43
Simple Diffusion
- Small nonelecrolyte solutes
- Fits through gaps between membrane lipids
- Non polar / minimal polarity
- Steroid hormones
- Fatty Acids
44
Diffusion goes from
High to low
45
Osmosis goes from
Low to high
46
how does water move in organs
Aquaporin
47
Aquaporin
- Small integral protein
- 4 subunits
- Quarternary Structure
- Lined by hydrophobic a.a.
- Specific for h20
48
Types of channel gating mechanisms
- Voltage gated
- Stretch gated
- Phosphorylation gated
- Ligand gated
49
States of the voltage gated pottasium channel
- Open
- Inactivated
- Closed
50
Bacterial KcsA Pottasium Channel
- Structure = Function
- Selectivity
- Carbonyl groups interacts with pottasium
51
How can you increase rate of carrier transport
- Increased graident of solute
- Increased carriers in the membrane
52
Example of fascilitated diffusion
Glucose Transporters
53
Insulin
Regulates blood sugar levels
54
Increase Blood Glucose
- Insulin secretion
- Glucose uptake into cell via carriers
55
Two types of Active Transport
- Primary Active Transport
- Secondary Active Transport
56
Primary Active Transport
- ATP is used primarily
57
Secondary Active transport
ATP is used indirectly
58
One impoertant feature of pumps
- Move ions
- Electroneutral
- Electrogenic
59
Na / K ATPase
- Found in animal cells
- 2K in and 3 Na out
- P type pump uses ATP, causes confromational changes
- Transport against concentration gradients
60
What type of pump is Na / K ATPase
Electrogenic
61
What tyoe of pump is electroneutral
H / K ATPase
62
H / K ATPase
- Stomach proton H+ Pump
- Acidifies stomach
- Exchanges 2 H+ for 2 K+
63
Co transport is what kind of active transport
Secondary
64
2 types of secondary co transporters
- Symporters
- Antiporters
65
Na / Glu pump is an example of
Symporter
66
Bacterial LeuT family
- Secondary transporter
- Established Na+ gradient helps to transport leucine to bacteria
- Symport
67
Neurons
Specialized cells that use changes in membrane potential to transmit a signal
68
Dendrites
Receive incoming information
69
Cell Body
contains the nucleus and the metabolic centre of the cell
70
Axon
A long extension for conducting outgoing impulses
71
What contributes to the membrane resting potential
Intracellular K + ions
72
What is the membrane resting potential
- 70mV
73
How are K + gradients maintained
Na / K ATPase
74
How are action potentials propagated?
- Local membrane currents depolarize adjacent membrane regions
- Unidirectional
- Nerve impulse retains intensity / strngth with propagation
75
Speed of neural impulse depends on
- Axon Diameter (Larger)
- Myelination
BMSC 220
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