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Mbb231 > Membrane Transport > Flashcards

Membrane Transport Flashcards

1
Q

Specific molecules and ions

A

Need to overcome selective permeability barrier
To moved in/out of cell

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2
Q

Dynamic steady state

A

Maintain an internal environment

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3
Q

Passive transport

A

-Down concentration gradient
-No energy expended
-Transport protein may need/or not

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4
Q

Active Transport

A

-Against concentration gradient
-Requires ATP
-Transport proteins(Pumps) are required

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5
Q

Simple diffusion

A

-Membrane permeability
-Favorable gradient conditions

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6
Q

Permeability is determined by

A

1-Molecular size
2-Partition coefficient/polarity
3-Charge

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7
Q

Concentration gradient

A

Move down concentration gradient
(Increase entropy)

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8
Q

Electric Potential Gradient

A

Move toward compartment with the net opposite charge

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9
Q

Thermodynamically favourable for charged molecules

A

Determined by electrochemical gradient

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10
Q

Thermodynamically favorable for no net charge

A

Determine by concentration gradient

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11
Q

Simple diffusion is possible for:

A

-gases
-nonpolar molecules
-Small polar molecules

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12
Q

Diffusion moves solute toward

A

Equilibrium

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13
Q

Passive/simple diffusion

A

Unassisted movement
Down concentration gradient

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14
Q

In capillaries of body tissues

A

Low o2
High co2

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15
Q

In capillaries of body tissues

A

O2 is released from hemoglobin

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16
Q

In capillaries of lungs

A

High O2
Low CO2

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17
Q

In capillaries of lungs

A

O2 diffuses inward
Bind hemoglobin

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18
Q

Osmosis

A

Diffusion of water through semi permeable membrane

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19
Q

Osmosis in plants

A

Plants are hypertonic compared to fluid environments

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20
Q

Plants in hypertonic solutions

A

Undergoes plasmolysis
Plant loses support and wilts

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21
Q

Thermodynamically simple diffusion is

A

Exergonic process
No energy required

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22
Q

Inward flux of solute and concentration gradient of solute

A

Simple diffusion

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23
Q

Facilitated transport

A

Requires protein:
-carriers
-channels

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24
Q

Carriers

A

Transporter alternate between two conformation
-Transport in either direction based on concentration gradient

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25
Channels
Water-filled pore -specific ions and small molecules diffuse
26
Channel proteins
Form hydrophilic channels through membrane Allow passage of solutes without conformational change
27
Carrier Proteins
Bind one or more solute molecules Undergoes conformational change
28
Channel proteins
Hydrophilic transmembrane channels
29
Channel proteins
1- Ion channels 2- porins 3- Aquaporins
30
Ion channels
-Highly-specific channel -Bidirectional -flow determine by electrochemical gradient -Most channels are gated
31
Porins
-Hydrophilic solutes -size limit Determined by pore size -Low specificity -Polar side chains inside -Nonpolar side chains point outside
32
Aquaporins
Water flows with rate if several billion per second
33
Most ion channels are
Selective for specific ion
34
Most ion channels are
-Gated — specific stimulus trigger -No need to undergo conformational changes with each ion it passes
35
Gated channels
-Voltage gated -Mechanically gated -ligand gated (intracellular or extracellular)
36
Channel positions
Open Close Inactive
37
Aquaporins
Water flows through at a rate of several billion per second
38
Carrier proteins
1- specific target molecule 2- activity regulated 3- exhibit saturation kinetic (V max)
39
Uniporter
Transport a single solute
40
Symporter
Two solutes in same direction
41
Antiporter
Two solutes in opposite direction
42
Coupled transport
Symport or antiport
43
Glucose uniport carrier protein
Glucose transporter GLUT1 -found in all mammalian plasma membrane -uses atp
44
Antiport carrier protein example
Chloride-Bicarbonate Exchanger (1:1) —aka anion exchange protein
45
Electrochemical gradient/potential
Concentration gradient and electrical gradient
46
Active transport
-Move solutes up a concentration gradient -Away from equilibrium -Couple endergonic transport to exergonic
47
Membrane proteins in active transport
Pumps
48
Active transport direction
Has intrinsic direction
49
Active transport three important cellular functions
1-Uptake if essential nutrients 2- Removal of waste 3-Maintenance non equilibrium concentration ions
50
Primary active transport
Coupled directly to an exergonic chemical rxn (ex. ATP hydrolysis)
51
Indirect(secondary) active transport
Endergonic is coupled to exergonic -may pumped uphill by primary active transport
52
Endergonic
Against concentration gradient
53
Exergonic
Down a concentration gradient
54
Difference of primary vs secondary
Source of energy
55
Primary active transport
ATPases harness energy of ATP HYDROLYSIS to move ions
56
P-type ATPases
Reversibly phosphorylated by ATP on specific aspartic acid residue
57
Sub families of p-type ATPases
Most found on plasma membranes -p1 in all organisms -p2-5 only in eukaryotes -p4 transport lipid (act as flippase)
58
2/3 of energy consumed by beain is used to ———
Maintain Na/K ATPase required for transmission of nerve impulses
59
V-type ATPase
Pump proton into organelles Only in eukaryotic
60
F-type ATPase
Transport protons in bacteria, mitochondria, chloroplasts -can work in both direction: ——endergonic —hydrolysis ATP ——exergonic—synthesize ATP
61
Reversible function of ATPases illustrates
ATP can be used as energy source to generate ion gradient Or Ion gradient can be used an energy source to synthesize ATP
62
MDR (multi-drug-resistant) transporter (ABC-type)
ABC transporter pump antibiotic or drug out of cell -Transport wide range of chemically dissimilar drugs
63
Indirect Active transport
Not powered by ATP -powered by potential energy stored in ionic gradient
64
Get glucose from digestive system into body
Na/Glucose symporter Glucose transporter Work together
65
Does indirect transport relies on ATP
Yes Because the conc. Gradient is generated by ATPase pump

Mbb231 (19 decks)

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