Cell Membrane and Transport

On the left side of your IntNB, draw the set-up of the

demonstration once it has been explained to you.

Make an hypothesis as to which direction the liquid will flow.

The plasma/cell membrane is selectively permeable

~only certain substances are allowed to pass through

What can and can not pass through the membrane?

CAN PASS THROUGH• Things that can

dissolve in fat• Small molecules• Water

CAN NOT PASS THROUGH

1. Things that can dissolve in water

2. Large molecules

3. Ions: Molecules with plus (+) or minus (-) charges

CH2OH

OH

What is an Isotonic Solution?

• [Water] inside cell = [Water] outside cell

• Cell is at equilibrium– Molecules are equally

distributed in end

• The amount of water entering the cell = the amount of water leaving the cell

95% 95% waterwater

95% 95% waterwater

What is a hypotonic solution?

• A solution that has MORE water, and LESS solute

• The cell can lyse or burst if left in a hypotonic solution

100% 100% waterwater

95% 95% waterwater

What is a hypertonic solution?

• A solution that has LESS water and MORE solute

• The cell will dehydrate90% 90% waterwater

95% 95% waterwater

What can pass through a membrane? (p. 253)

Can pass through membrane

Cannot pass through membrane

Solubility?

Size?

Charge?

Water solubleFat soluble

Small Large

Uncharged Molecules

Ions (H+, Na+, HCO3-, K+…)

The Plasma Membrane (p. 251)

TEM of a red blood cell

Hydrophilic Region

Hydrophilic Region

Hydrophobic Region

Phospholipid

Proteins

Carbohydrate side chainsGlycoprotein

Inside of Cell

Outside of Cell

No energy is used[High] [Low] (it’s the natural flow)

This means it goes down a concentration gradient

There are three types…

[High] [Low]

Passive Transport: Diffusion

OsmosisPassive Transport: Osmosis (Diffusion of water)

Facilitated Diffusion+ CH2OH

OH

Passive Transport: Facilitated Diffusion

Energy is used[Low] [High]

This means it goes up or against a concentration gradient

There are three types…

Protein Pumps

Protein Pumps: proteins use energy to pull or pump materials into or out of the cell to stockpile or storestore substances the cell needs

Active Transport: Protein Pumps

Different Types of Membrane Proteins (page 252)

TRANSPORTERS RECEPTORS ENZYMESSIGNAL/ RECOGNITION

Different Types of Membrane Proteins (page 252)

signal/recognition

Enzymes

receptor

transporter

Endocytosis• When cells engulf particles into the cell• 2 types

1. Phagocytosis: When a cell wraps part of its membrane arounda large particle forming a “pocket” or vesicle

2. Pinocytosis: The same process, but with smaller particles or liquids

Active Transport: Endocytosis

Exocytosis

1. A vesicle carrying a substance

2. fuses with the cell membrane

3. and releases the substance

Active Transport: Exocytosis