Types of Transport Across Cell Membranes

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Passive Transport

Simple Diffusion

Requires NO energy

Molecules move from area of HIGH to LOW concentration

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Simple Diffusion4

no energy is used to make the molecules move because they have a natural KINETIC ENERGY

Diffusion of Liquids5

Diffusion through a Membrane6

Cell membrane

Solute moves DOWN concentration gradient(HIGH to LOW)

Diffusion Animation

Movement of particles from an area of concentration to an area of concentration.

Osmosis

Diffusion of water across a membrane

Moves from HIGH water potential (low solute) to LOW water potential (high solute)

No Energy needed

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Diffusion across a membrane

Semipermeable

membrane

Diffusion of H2O Across A Membrane

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High H2O potentialLow solute concentration

Low H2O potentialHigh solute concentration

Osmosis

Net diffusion of H20 across a semi permeable membrane

ISOTONICHYPOTONIC

HYPERTONIC

Types of Solutions

Isotonic

Concentration of solute is equal on both sides of the membrane

No water net water movement

Hypotonic

Solute concentration is less outside the cell Therefore more water outside the cell

Water moves into the cell CYTOLYSIS (blows up)

Hypertonic

Solute concentration is greater outside the cell Therefore more water inside the cell

Water moves out of the cell PLASMOLYSIS (shrivels)

Cell in Isotonic Solution15

CELL

10% NaCL90% H2O

10% NaCL

90% H2O

What is the direction of water movement?The cell is at _______________.equilibrium

ENVIRONMENT

NO NET MOVEMENT

Cell in Hypotonic Solution16

CELL

10% NaCL90% H2O

20% NaCL

80% H2O

What is the direction of water movement?

Cell in Hypertonic Solution17

CELL

15% NaCL85% H2O

5% NaCL95% H2O

What is the direction of water movement?

ENVIRONMENT

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Isotonic Solution

NO NET MOVEMENT OF

H2O (equal amounts entering

& leaving)

Hypotonic Solution

CYTOLYSIS

Hypertonic Solution

PLASMOLYSIS

Cytolysis & Plasmolysis19

Cytolysis Plasmolysis

Osmosis in Red Blood Cells20

Isotonic Hypotonic

Hypertonic

Transport with Proteins

Types of Transport Proteins22

Channel proteins are have a pore for materials to cross

Carrier proteins can change shape to move material

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Transport with Proteins

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Facilitated Diffusion

Doesn’t require energy

Uses transport proteins to move substances from high to low concentration

Examples: Glucose or amino acids moving from blood into a cell.

Facilitated Diffusion

Carrier protein helps diffusion occur (no energy)

Active Transport

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Active Transport

Requires energy or ATP

Moves materials from LOW to HIGH concentration

AGAINST concentration gradient

Active Transport

Use energy (ATP) to move particles against the concentration gradient.

Active transport

Examples: Pumping Na+ (sodium ions) out and K+ (potassium ions) in against strong concentration gradients.

Called Na+-K+ Pump

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Moving “Big” Stuff

Endo or Exocytosis

Endocytosis Intake

Exocytosis Export

Both move large molecules through the creation of vessicles.

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Excocytosis – Move Out

Molecules are moved out of the cell by vesicles that fuse with the plasma membrane.

This is how many hormones are secreted and how nerve cells communicate with one another.

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ExocytosisExocytic vesicle immediately after fusion with plasma membrane.

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Endocytosis – Move inLarge molecules move materials into the

cell by one of two forms of endocytosis.

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Pinocytosis – cell drinking

Most common form of endocytosis.

Takes in dissolved molecules as a vesicle.

Pinocytosis

Cell forms an invagination

Materials dissolve in water to be brought into cell

Called “Cell Drinking”

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Phagocytosis – Cells Eating

Used to engulf large particles such as food, bacteria, etc. into vesicles

Called “Cell Eating”

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Phagocytosis About to Occur

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Phagocytosis - Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue)