Chapter 3.4

Question 1

What is Tonicity?

Answer 1

the ability of a solution to affect fluid volume and pressure in a cell .

-depends on concentration and permeability of solute

Question 2

What are transport proteins?

Answer 2

In the plasma membrane, transport proteins carry solutes from one side of the membrane to the other.

• Saturation: As the solute concentration rises, the rate of transport rises, but only to a point - Transport Maximum (Tm).

2 types of carrier mediated transport:
Facilitated diffusion and active transport

Question 3

List the types of Membrane Carriers

Answer 3

Uniport - carries only one solute at a time

Symport - carries 2 or more solutes simultaneously in the same direction (contrasport)

Antiport -Carries 2 or more solutes in opposite directions ( counter-transport) . Sodium-potassium pump brings in K+ and removes Na+ from cell

Question 4

What is Facilitated diffusion?

Answer 4

carrier mediated transport of solute though a membrane down its concentration gradient

• does not consume ATP
• solute attaches to binding site on carrier, carrier changes confirmation, then releases solute on other side of membrane.

Question 5

What is Active transport?

Answer 5

carrier mediated transport of solute though a membrane up (against) its concentration gradient

• ATP energy consumed to change carrier
• Examples of uses: sodium-potassium pump keeps K+ concentration higher inside the cell
• bring amino acids into cell
• pump Ca2+ out of cell

Question 6

How does a Sodium-Potassium Pump work?

Answer 6

each pump cycle consumes one ATP and exchanges three Na+ for two K+

keeps the K+ concentration higher and the Na+ concentration lower with in the cell than in ECF

necessary because Na+ and K+ constantly leak though membrane

Question 7

What are the functions of Na+ K+ pump?

Answer 7

• Regulation of cell volume
• Secondary active transport
• heat production
• maintenance of a membrane potential in all cells