Part 1

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% water

95% water

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% water

95% water

What is a hypertonic solution?

• A solution that has LESS water and MORE solute

• The cell will dehydrate90% water

95% water

Which direction does water flow?

a) Water doesn’t flow at all.

b) Water flows from an area of low concentration to an area of high concentration.

c) Water flows from an area of high concentration to an area of low concentration.

Lipids2. Phospholipids

– Glycerol with Phosphate Head + 2 Fatty Acid Chains

– Amphiphilic (“Both” “lover”)• Hydrophilic head• Hydrophobic tail

– Forms 2 layers in water– Makes up cell membranes

Organic Compounds: Lipids: Phospholipids

Phosphate

Glycerol

Fatty Acids

phospholipid Membraneproteins

Hydrophobicregion

Hydrophilic heads of phospholipids

Carbohydrate side chain

MarkerProteins (has carbohydrate side chain attached)

Different Types of Membrane Proteins (page 77)

TRANSPORTERS RECEPTORS ENZYMESSIGNAL/ RECOGNITION

Different Types of Membrane Proteins (page 77)

signal/recognition

Enzymes

receptor

transporter

The plasma/cell membrane is selectively permeable

~ It controls what enters and leaves the cell ~ only certain substances are allowed to pass

through

What can and can not pass through the membrane?

CAN PASS THROUGH

• Other lipids and fatty substances that dissolve in fat (hydrophobic)

• Small molecules, like water

• Things w/o charge

CAN NOT PASS THROUGH

1. Water-like substances (hydrophilic)

2. Large molecules

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

CH2OH

OH

CH2OH

OH

Go to page 78…

• Fill in the table…• What substances can pass through the

membrane?

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

This means it goes down a concentration gradient

3 types of Passive Transport

1. Diffusion2. Osmosis3. Facilitated Diffusion

Diffusion

[High] [Low]

Osmosis

Facilitated Diffusion+ CH2OH

OH

Passive Transport: Facilitated Diffusion

Channel protein

Energy is used[Low] [High]

This means it goes up or against a concentration gradient

3 Examples of Active Transport

1. Protein pumps2. Endocytosis3. Exocytosis

Protein Pumps

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

Go to page 87 - 88

8

2

1

6

7

4

3

5

Now complete page 88 to check your understanding

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

Exocytosis(opposite of endocytosis)

1. A vesicle carrying a substance

2. fuses with the cell membrane

3. and releases the substance

Inside the cell Outside the cell

Check for understanding

• Complete pages 100 – 101 Section Review