1. Movement of Materials In and Out of a Cell
Cellular Transport
Movement of Materials
In and Out of a Cell

2. Plasma Membrane Maintains homeostasis (stable environment)
Membrane is “selectively permeable”
Only certain things can pass in and out

3. Structure of the Plasma Membrane
Fluid Mosaic Model
Membrane is not rigid
Molecules can move back and forth (fluid)

4. Phospholipid Bi-layer
2 layers of Phospholipids
Hydrophobic tails and hydrophilic heads

5. Cholesterol molecules:
sometimes found embedded in membrane to give it more strength and rigidity.
Carbohydrate Chains: help cells identify each other

6. Membrane Proteins Protein Channels Anchor Proteins Enzyme Proteins
Provide pathway for movement of certain materials
Anchor Proteins
Anchor molecules in membrane so they don’t move around
Enzyme Proteins
Take part in chemical
reactions

7. Receptor Proteins Act as binding sites for specific molecules
Cellular communication
Recognize foreign cells
Tell cell to begin or stop activity

10. Movement in a Liquid Medium
Cytoplasm has many different things dissolved in it.
Solvent = water
Solute = stuff dissolved (ex: sugar, salt)
Solution = the mixture of solvent and solute
Concentration = how much is dissolved

11. All molecules are in constant random motion, so over time they will move from one location to another.

12. Types of Transport

13. Passive Transport Doesn’t require energy
Diffusion:
Movement of materials through the cell membrane.
Higher concentration to lower concentration
Does not require energy (ATP)
Ex: oxygen, carbon dioxide, water

14. Dynamic Equilibrium: a point of balance that is reached when concentrations stop changing (but particles still moving!)

15. Example of Diffusion Higher Concentration Outside
Particles Diffuse Into Cell
Equilibrium Reached
(Diffuse In & Out Equally)

16. Facilitated Diffusion:
Protein channels facilitate (help) movement of charged ions and large molecules like glucose to cross cell membrane
Energy (ATP) not needed

17. Osmosis: Movement (diffusion) of WATER through the cell membrane
From high concentration to low (of water)
No energy needed

18. Aquaporins: Water channel proteins Involved in osmosis
Allow water to move easily through membrane by diffusion
Type of facilitated diffusion
Oil (fat) and water don’t mix
Channel helps water get through fatty membrane!!!

19. Water moves into an area that is more concentrated with solute particles!!!!
Equilibrium is reached and concentrations are equal on both sides of membrane

20. Osmosis
Water moves to area where water is less concentrated

22. Osmotic Pressure: force caused by net movement of water into or out of cell

23. Isotonic Solution: of the same “strength”
Same concentration as cell
Hypertonic Solution: “above strength”
More concentrated than cell
Hypotonic Solution: “below strength”
Less concentrated than cell

24. What will Happen? To a cell in a: Isotonic Solution?
Hypertonic Solution?
Hypotonic Solution?
Which way will water move?
Will it fill up and burst, shrink, or stay the same?
Types of Solutions:
Egg Experiment:

26. Plasmolysis: when a plant cell loses water
Normal plant cell – large vacuole stores water
In salt water, or in times of drought – water leaves cell to go into surroundings (wilts)

27. Active Transport: Requires energy (ATP)
Materials are moved from low to high concentration

28. Protein Pumps: Membrane proteins
Move small molecules and ions across membrane
Against concentration gradient (low to high)
Requires energy (ATP)

29. Endocytosis Folding in the membrane to form a vacuole
Take in large molecules, clumps of food or whole cells
Requires energy

30. Types of Endocytosis Phagocytosis Cell “eating”
Cell engulf large particles by sending out extensions of cytoplasm
Ex:
Amoeba sends out pseudopods,
White blood cells eat bacteria and damaged cells

31. Pinocytosis Cell “drinking” Cell takes in liquid
“Pinching in” of cell membrane to create a storage vacuole

32. Exocytosis Cells releasing (excreting) materials
Membrane of vacuole fuses with cell membrane

33. Inner Life of the Cell