TRANSPORT MECHANISMS Flashcards
1
Q
The cell membrane is (selectively/nonselective) permeable and restricts the movement of _______ ______
A
selectively and soluble gases
2
Q
High or Low Permeability: Dissolved Gases (O2, CO2)
A
High Permeability
3
Q
High or Low Permeability: Small uncharged molecules
A
High Permeability
4
Q
High or Low Permeability: H2O
A
High Permeability
5
Q
High or Low Permeability: Lipid Soluble Substances
A
High Permeability
6
Q
High or Low Permeability: Larger Molecules
A
Low Permeability
7
Q
High or Low Permeability: Charged Particles
A
Low Permeability
8
Q
Match: Hydrophilic/Hydrophobic - polar/non-polar
A
Hydrophilic - polar
Hydrophobic - non-polar
9
Q
Cell membrane consists of _____ heads and ______ tails
A
Hydrophilic, hydrophobic
10
Q
Structure of cell membrane
A
Bimolecular Phospholipid Bilayer
11
Q
Amphipathic
A
Polar and Non-Polar ends
12
Q
Where is cholesterol inserted?
A
Bilayer
13
Q
Purpose of cholesterol bilayer insertion
A
- Reduces packing of fatty acid tails (slightly amphipathic)
- Increases membrane fluidity
- Formation of vesicles
14
Q
Glycocalyx
A
A layer of carbohydrates formed by a chain of monosaccharides
15
Q
What is glycocalyx bound to?
A
Protein
16
Q
Purpose of glycocalyx
A
Protection, identify and interact with other cells
17
Q
Two types of membrane proteins
A
Integral and Peripheral
18
Q
What are integral proteins
A
Mostly cross the membrane, closely associated with phospholipids, for transport
19
Q
What are peripheral proteins
A
Loosely associated, mostly on the cytoplasmic side
20
Q
Cell membrane is not ________
A
static
21
Q
What are the functions of Membrane Proteins? (6)
A
- Transport/diffusion of molecules in and out of cells
- acts of enzymes that catalyze membrane reactions
- receptor of signals from the cell environment
- Cell surface identity markers
- Cell to cell adhesion
- Attachment to cytoskeleton
22
Q
Types of Transport Mechanisms
A
Passive and Active
23
Q
Match: Passive/Active - Energy dependent/independent
A
Passive - Energy independent
Active - Energy-dependent
24
Q
Types of passive transport mechanisms (3)
A
- Diffusion
- Facilitated Diffusion
- Osmosis
25
Types of active transport mechanisms (1ab-2)
1. Active Transport
- primary, secondary
2. Pino/Phagocytosis
26
What is diffusion?
Movement of molecules from one location to another due to random thermal motion
27
What is flux?
amount of particles crossing a surface/time
28
What is net flux?
high concentration to lower concentration
29
What are the flux and net flux at equilibrium?
Flux - equal
| Net flux = 0
30
When cells are exposed to a large extracellular solution the concentration is _______
constant
31
DIffusion time is proportional to the _____ of the ______
square of the distance
32
Diffusion is only effective over _____ distances
short
33
Factors that affect diffusion: (5)
```
Mass of molecule
concentration gradient (cell membrane)
Lipid solubility
Electrical Charge
Availability of ion channels and membrane carriers
```
34
How do molecules cross membranes?
Dissolving in lipid component (non-polar)
| Diffusing through the channel (ions)
35
Ion channels consist of one or clusters of _______
Proteins
36
The movement of ions is affected by an ________ gradient
Electrical
37
What is ion channel gating?
Ion channel can exist in open and closed state
38
What are the types of ion channel gating?
Ligand Gated
Voltage-Gated
Mechanically Gated
39
What does the voltage gate depend on?
conductance, how often/long it opens
40
What does the Ligand gate depend on?
Presence of Ligands
41
The movement of ions and molecules by integral proteins (transporters)
Mediated-Transport Systems
42
Speed of Mediated Transport systems vs Ion Channels
Mediated Transport systems are much slower than Ion Channels
43
Two types of Mediated Transport systems?
Facilitated Diffusion and Active Transport
44
Characteristics of Mediated Transport (3)
Specificity (one particular molecule), Saturation (binding sites are occupied), Competition (structurally similar substance compete for binding site)
45
Factors of Flux Magnitude (4)
1. Solute Concentration
2. Affinity of Transporters
3. Number of Transports
4. Rate of Transporters conformational change
46
What may increase facilitated diffusion?
hormones
47
What is facilitated diffusion?
carrier
| which enables solute to penetrate the membrane
48
Facilitated diffusion is _______ mediated
Transporter (carrier)
49
Facilitated diffusion (does/does not) require energy
Does not
50
Facilitated diffusions net flux from ____ to ____ concentration
high to low concentration
51
Active Transport (does/does not) require energy
does
52
Active Transport obtains energy through the ______ of ______
Hydrolysis of ATP
53
Active Transport goes ______ the concentration gradient
against
54
Active transport is susceptible to ______ ______
metabolic inhibitors
55
Two types of Active Transport?
Primary and Secondary
56
How does Primary Active Transport occur?
Hydrolysis of ATP
57
Phosphorylation of transporter changes the __________ and __________
Confirmation and Solute Binding Affinity
58
How does Secondary Active Transport occur?
Uses energy stored in the electrochemical gradient to move the ion and transported solute
59
What does secondary transport depend on?
Primary Transport
60
Cotransport
Solute transport in the same direction as Na+ (symport)
61
Counter Transport
Solute transport in opposite direction as Na+ (antiport)
62
Endocytosis
Cell membrane invaginates and pinches off to form a vesicle
| Materials inside to outside the cell
63
Exocytosis
intercellular vesicle fuse with cell membrane, contents released into ECF
Materials outside to inside the cell
64
2 Types of Exocytosis
Constitutive and Regulated
65
2 Types of Endocytosis
Pinocytosis and Phagocytosis
66
Constitutive
non-regulated, functions to replace plasma membrane
67
Regulated
triggered by extracellular signals, increase of calcium ion
68
Pinocytosis
Engulfs extracellular fluid, solutes
69
Phagocytosis
Binds and internalizes matter (dust particles, cell debris, microorganisms)
Form large vesicles (phagosomes) --> fuse with lysosomes where contents are degraded
70
Two types of receptor-mediated endocytosis
Catherine dependent
71
What is Catherine dependent receptor-mediated endocytosis?
```
The receptor binds to the ligand
Catherine proteins forming a clathrin-coated pit
Vesicle forms
unbound ligands to the nucleus
receptor recycled to the membrane
fuse with lysosome
```
72
What is potocytosis? also known as
molecules are sequestered and transported by tiny vesicles, Catherine independent
73
Tiny vesicles in potocytosis
caveolae
74
Deliver to the cell cytoplasm, ER, other organelles, or other plasma membranes
potocytosis
75
Deliver molecules to other plasma membranes
transcytosis
76
Diffusion of water occurs by
facilitated by proteins (aquaporins)
77
aquaporins form ______ channels
permeable
78
Osmosis
Net diffusion of H2O
79
Osmotic Pressure
The pressure required to prevent movement of H2O
| The difference in Hydro Static Pressures
80
Osmolarity
Total Solute Concentration
81
How many osmols in 1M NaCl
2 osmol: 1 osmol (Na+) + 1 osmol (Ca-)
82
Isomotic Solution (mOsm)
300 mOsm
83
Hypoosmotic Solution (mOsm)
Less than 300 mOsm
84
Hyperosmotic Solution (mOsm)
Greater than 300 mOsm
85
What are non-penetrating molecules?
particles not able to cross the membrane
86
molecules pumped against the concentration gradient
non-penetrating molecules
87
Isotonic Solution (mOsm)
Solution of 300 mOsm with non-penetrating particles
88
Hypotonic Solution (mOsm)
Solution of less than 300 mOsm with non-penetrating particles
89
Hypertonic Solution (mOsm)
Solution of more than 300 mOsm with non-penetrating particles
90
What is the capillary wall?
Single-layer of flattened endothelial cells and a supporting basement membrane
91
Where does the main exchange of solutions take place?
Capillaries
92
What does the capillary wall allow for?
Acts as a filter that allows protein-free plasma from capillaries to ISF
93
Endocytosis on the luminal side
Transcytosis
94
Transport in vesicle across cell
Transcytosis
95
Exocytosis on interstitial side
Transcytosis
96
Distributes the ECF fluid volume between the plasma and ICF
Bulk Flow
97
The magnitude of Bulk flow
hydrostatic pressure between plasma and ISF
98
FACILITATED DIFFUSION involves the presence of a
“transporter” or “carrier” molecule
99
Common molecules transported by facilitated diffusion
glucose
