Bellringer-December 11, 2014• 1. If a cell contains 85% water and is placed into a environment which is 50% water.

Is the CELL hypotonic or hypertonic? In which direction will the water move, into the cell or out of the cell?

• 2. A cell contains 85% water and is placed into a solution which contains 90% water. Is the SOLUTION in the environment hypotonic or hypertonic? In which direction will the water move?

• 3. A cell contains 95% water, the environment outside the cell contains 45%

solutes. Is the cell in a hypotonic or hypertonic environment?

• 4. A cell containing 25% solutes is placed into a solution which contains 35% solutes. Which direction will the water move, into the cell or out of the cell?

• 5. A plant cell containing 95% water is placed into a 10% salt solution. Is the salt solution hypotonic or hypertonic? Which direction will the water move?

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ACTIVE TRANSPORT

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Remember….• Passive Transport does NOT require energy• Types of passive transport:

• Diffusion• Facilitated Diffusion• Osmosis

Active Transport • Requires energy! • Molecules move against (up) their concentration

gradients (from LOW concentration to HIGH)• Cells use energy to power this process• Two types: Endocytosis and Exocytosis

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Active transport• Uses energy to move solutes against

their [ ] gradients across the cell membrane–Energy required usually ATP

• Carrier proteins are used…NEVER channel proteins– Ex: sodium-potassium pump

Passive vs. Active Transport

Figure 7.17

1. PROTEIN PUMPS•Protein Pumps -transport proteins that require energy to do work•Examples: • Na+/K+ Pumps are

important in nerve responses

• H+ (proton) pump

Sodium Potassium Pumps (Active Transport using

proteins)

Protein changes conformational shape to move molecules: this

requires energy!

2. Bulk transport across the plasma membrane

• Occurs by exocytosis and endocytosis• BOTH MOVE “BIG” AMOUNTS

OF STUFF in OR out OF THE CELL

Exocytosis• USES ENERGY! • Moves “BIG” materials OUT of the cell• Vesicle moves to the plasma membrane and

fuses with it, contents are emptied from the cell– “exo-” means “exit”– Ex: hormone excretion; nerve cells and

transmitters; removal of wastes

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Exocytosis

ER

ROUGH ER

Glycolipid

Vesicle

Membrane glycolipid

Secretedprotein

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2

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GOLGI APPARATUS

Endocytosis• USES Energy! • Brings “BIG” materials INTO the cell

• Cell takes in macromolecules by forming new vesicles from the plasma membrane– “endo-” means “enter”

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Endocytosis

2 types of Endocytosis1. Phagocytosis

“cell eating” Cell engulfs SOLIDS into

vesicle & “digests” it2. Pinocytosis (think

“pineapple juice) “cell drinking” Cell engulfs LIQUIDS into

vesicle & “digests” it

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Additional Notes T- CHART

Passive Transport

1. NO ENERGY NEEDED

2. THREE SUB UNITS- Osmosis- Diffusion- Facilitated Diffusion3. HIGH to LOW4. SMALL MOLECULES

Active Transport

1. YES! ENERGY NEEDED2. TWO SUB UNITS- Exocytosis- Endocytosis3. LOW to HIGH4. BIG MOLECULES

DON’T FORGET