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)
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