Lecture 3

Question 1

Ionic Properties of Cells:

Answer 1

• Every cell maintains intracellular concentration of inorganic solute that are very different from those of the extracellular environment
• These ionic gradients across the cell membranes are so important to cell function that the cell spends a great deal of energy to maintain them (ex. Na+/K+ - ATPase)

Question 2

Simple Diffusion

Answer 2

• Molecules more constantly and randomly
  Over time, more molecules move at random from an area of high concentration to an area of low concentration. This process is passive (no energy needed)

Question 3

Fick’s Law of Diffusion:
J = D x ((C1 - C2)/X)

Answer 3

J: rate of diffusion or quantity of solute diffusing per unit time
D: Diffusion coefficient
C1: Value of high concentration
C2: Value of low concentration
X: Distance between C1 and C2

Question 4

Fick’s Law of Diffusion:
D= P/(square root)MW

Answer 4

D: Diffusion coefficient
P: Permeability
MW: Molecular weight

Question 5

Electrochemical Gradients:

Answer 5

• Ionic charges separation occurs only with nanometers
• determines the movements of solutes across a permeable membrane
• when the chemical and electrical gradients are in the same way, diffusion is fast

Question 6

Osmosis

Answer 6

Is the diffusion of water through a semipermeable membrane from a region of low solute concentration to a region of high solute concentration

Question 7

Osmosis and Hydrostatic Pressure (water movement)

Answer 7

Water stops moving when the hydrostatic pressure equals the osmotic pressure

Question 8

Osmotic Pressure

Answer 8

Property of a solution that allows you to predict which way water will move

Question 9

Osmolarity

Answer 9

• Total dissolved entities per liter
• is the unit of measure or osmotic pressure

Question 10

Tonicity

Answer 10

• The effect of a solution on cell volume

Question 11

Effect of Tonicity

Answer 11

Depends on differences in osmolarity but also on the permeability of the membrane to the solutes
Ex. Whether or not the solute can enter the cell

Question 12

Osmosis Vs. Tonicity

Answer 12

• Osmolarity considers the total concentration of penetratind of non- penetrating solutes
• Tonicity relates only to the total concentration or non-penetrating solutes

Question 13

Donnan Equilibrium

Answer 13

• Predicts that the distribution of ions across a membrane will be unequal if the membrane is impermeable to one or more types of charged particles
• Animal cells tend towards this equation because they contain a high concentration of non-permeating avionics molecules (A-)

Question 14

Rule #1: Donnan Equilibrium

Answer 14

Principle of Electroneutrality

Question 15

Rule #2: Donnan Equilibrium

Answer 15

The product of the concentration of permeant ions inside the cell equals the product of the concentration of permeant ions outside the cell

Question 16

Rule #3: Donnan Equilibrium

Answer 16

Osmolarity inside/outside the cell must balance

Question 17

OLEK

Answer 17

Zabinski