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

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.

Lipids

• Lipids function in:– Energy (E) storage, – forming cell membranes, – and as chemical messengers

(e.g., hormones)

• Nonpolar (hydrophobic)

• Made up mostly of Carbon and Hydrogen (with a few Oxygen)

Lipids1. Fats (Triglycerides)

– Glycerol + 3 Fatty Acids– Saturated = No Double Bonds (solid)– Unsaturated = Double Bonds (liquid)

OH

OH

OH

OH

OH

OH

Ester Bonds

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

Egg lab

• Dissolve egg shells

• Rinse

• Calculate initial mass

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

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

This means it goes down a concentration gradient

There are three types…

3 types of Passive Transport

1. Diffusion2. Osmosis3. Facilitated Diffusion

Diffusion

[High] [Low]

Osmosis

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…

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 storestore substances the cell needs

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

1. A vesicle carrying a substance

2. fuses with the cell membrane

3. and releases the substance