Pumps And Transports

Front 1

What is the driving force of passive transport?

Back 1

1. The kinetic energy of particle movement is used.
2. Substances move from areas of high concentration to lower, which continues until equilibrium is reached.

Front 2

What affects the rate of diffusion?

Back 2

Concentration gradient, distance, temperature and size

Front 3

What determines the rate of diffusion across a membrane?

Back 3

Membrane surface area, thickness and permeability as well as the concentration gradient.

Front 4

What does membrane permeability to a substance depend on?

Back 4

1. lipid solubility of the diffusing substance
2. size of the diffusing substance
3. lipid composition of the membrane

Front 5

How do transmembrane proteins play a role in facilitated diffusion?

Back 5

Function as carriers across a membrane by undergoing a conformational change.

Front 6

What is the direction of movement in facilitated diffusion?

Back 6

Down a concentration gradient

Front 7

What is the difference in rate of diffusion b/e facilitated and simple diffusion?

Back 7

The rate of facilitated diffusion accelerates quickly but peaks out, simple diffusion has a steady acceleration up to a Vmax. Eventually catching up to facilitated

Front 8

What are Aquaporins?

Back 8

Allow for the movement of water across membranes

Front 9

What are ion channels?

Back 9

May be water-filled through which ions diffuse or they may possess one or more binding sites for a specific ion.

Front 10

What does transport rate through a channel depend on?

Back 10

Properties of the channels and the number of channels.
*channel saturation can occur.

Front 11

What controls the opening and closing of protein channels?

Back 11

Conformational changes w/in the channel, which can be:
1. Voltage gated; changes are controlled by voltage effects
2. mechanically gated; stretch or other factors open the channels (like in the ear)
3. Chemically gated; ligand binds and triggers channel opening.

Front 12

What is active transport?

Back 12

Energy is expended to transport a substance against its concentration gradient

Front 13

What are properties of primary active transport?

Back 13

Requires ATP and the proteins are ATPases.

Front 14

What is the Na/K ATPase?

Back 14

A perfect example of primary active transport:

W/ each cycle three Na and two K are antiported across the membrane.

Front 15

What determines the rate of primary active transport?

Back 15

1. Properties of pump proteins
2. Number of pumps

Front 16

Can primary active transport pumps be saturated?

Back 16

Yep

Front 17

What is secondary active transport?

Back 17

Transport protein couples the passive movement of a substance down its electrochemical concentration gradient releasing energy that drives the movement of another substance against its electrochemical gradient.

Front 18

What is symport?

Back 18

Two substances moved in the same direction

Front 19

What is antiport?

Back 19

Two substances moved in opposite directions

Front 20

Does simple diffusion require...
1. transport proteins?
2. energy? (ATP or otherwise)
3. an energy source?
4. saturation?
5. specificity?
6. what is the direction of net flux?

Back 20

1. No
2. No
3. No
4. No
5. No
6. Down electrochemical gradient

Front 21

Does channel diffusion require?
1. transport proteins?
2. energy?
3. energy source?
4. saturation?
5. specificity?
6. what is the direction of net flux?

Back 21

1. Yes, ion channels
2. No
3. No
4. Possible
5. Yes
6. Down electrochemical gradient

Front 22

Does facilitated diffusion require...
1. transport proteins?
2. energy?
3. energy source?
4. saturation?
5. specificity?
6. what is the direction of net flux?

Back 22

1. yes, carrier proteins
2. no
3. no
4. yes
5. yes
6. down electrochemical gradient

Front 23

Does primary active transport require...
1. transport proteins?
2. energy?
3. energy source?
4. saturation?
5. specificity?
6. what is the direction of net flux?

Back 23

1. yes, pump proteins
2. yes
3. ATP
4. yes
5. yes
6. up electrochemical gradient

Front 24

Does secondary active transport require...
1. transport proteins?
2. energy?
3. energy source?
4. saturation?
5. specificity?
6. what is the direction of net flux?

Back 24

1. yes, pump proteins
2. yes
3. electrochemical gradient
4. yes
5. yes
6. up electrochemical gradient

Front 25

What is osmosis?

Back 25

Passive transport of water across a membrane down its concentration gradient

Front 26

What affects the movement of water during osmosis?

Back 26

Solute concentration gradients across a membrane affect the movement of water.

Water moves from lower solute concentration to higher solute concentration.

Front 27

How do aquaporins in tight junctions affect osmosis?

Back 27

Accomodate the movement of water paracellularly while those in cell membranes allow the transcellular movement of water.

Front 28

What is osmolarity?

Back 28

The concentration of solute particles in a solution. (in mOsm)

Front 29

What is an isoosmotic solution?

Back 29

Two solutions of the same osmolarity

Front 30

What is a hyperosmotic solution?

Back 30

A solution of higher osmolarity than another

Front 31

What is a hypoosmotic solution?

Back 31

A solution of lower osmolarity than another

Front 32

What is normal physiologic osmolarity?

Back 32

285-295

Front 33

What is the osmotic pressure?

Back 33

The pressure required to stop the osmotic flow of water across a membrane.

Front 34

What is the tonicity?

Back 34

The concentration of nonpermeable solutes outside a cell compared to the concentration of nonpermeable solutes inside a cell affects osmosis and therefore cell volume.
Example: putting a RBC in a isoosmotic sol'n has no effect, but a hypertonic sol'n would cause the cell to shrink while a hypotonic sol'n would cause the cell to swell.

Front 35

What is endocytosis?

Back 35

Extracellular fluid and and/or particles cross membranes by phagocytosis, pinocytosis or receptor mediated endocytosis

Front 36

Briefly describe receptor-mediated endocytosis

Back 36

Binding of extracellular material to membrane receptors called clathrin that forms a coated pit. The endosome contains the receptors and the bound material but the vesicle decoats prior to forming an endosome.

Front 37

What cell are polarized?

Back 37

Epithelial cells specialized for absorption and secretion

Front 38

What is cell polarization?

Back 38

Cells w/ different transporters on the apical side than on the basolateral side.

Front 39

What does any transporter involving sodium depend on?

Back 39

The Na/K exchanger on the basolateral side