1. Unit 2 Notes: Cell Membrane Transport

2. (1) Cell Membrane
Definition: The semi-permeable outer-covering of all cells.
Composition:
2 Phospholipid Layers (Bilayer)
Protein Channels embedded
Purpose / Function:
Control traffic in and out of the cell
Protection

5. (2) Cell Membrane Transport
Methods:
Diffusion (No energy needed)
Osmosis (No energy needed)
Facilitated Diffusion (No energy needed)
Active Transport (Energy needed)
“Transport” = Things moving in and out of the cell.

6. (3) Concentration
Definition: The amount of matter in a given amount of space (area).
High Concentration = More matter in a given amount of space.
Low Concentration = Less matter in a given amount of space.
“Concentration Gradient”: A difference in concentrations.

8. (4) Permeability
Definition: The ability of matter to move across a boundary.
Cell Membranes are Semi-Permeable.
“Semi-Permeable”: The ability of only certain types of matter to move across a boundary.

9. Fully Permeable
Not Permeable
Semi- Permeable

10. (5) Equilibrium Definition: State of balance.
Matter moves in and out of cells to reach equilibrium.

11. (6) Diffusion
Definition: The movement of particles across a concentration gradient, from an area of higher concentration, to an area of lower concentration, without the use of cell energy (ATP).
REMEMBER: HIGH  LOW

13. (7) Facilitated Diffusion
Definition: The movement of larger biomolecules across protein channels in the cell membrane, without the use of energy (ATP).
How is this different?
Larger molecules cannot diffuse normally.
Need larger membrane openings.

15. (8) Osmosis
Definition: The movement of water particles, across a concentration gradient, from an area of higher water concentration, to an area of lower water concentration.
REMEMBER: HIGH  LOW
Osmotic Environments:
Isotonic  Same amount of water inside + out.
Hypertonic  Too much water inside the cell.
Hypotonic  Not enough water inside the cell.

19. (9) Solute & Solvent Solute: Solid particles
Sugar
Salt
Solvent: Liquid which dissolves solute.
Water

21. (10) Active Transport
Definition: The forced movement of molecules, across a semi-permeable membrane, AGAINST the concentration gradient, using cell energy (ATP).
REMEMBER: Against the Gradient & ATP
Why Would Cells Do this?
Sometimes cells need a lot of a biomolecule (sugar), and need to go beyond equilibrium.

23. (11) The “-Cytosis” Processes
Endocytosis: Bringing materials into a cell by folding them into bits of the cell membrane.
Phagocytosis: A type of endocytosis where cells hunt the materials first.
Pinocytosis: The endocytosis of liquid materials into the cell.
Exocytosis: The releasing of materials/wastes out of the cell by wrapping them in bits of cell membrane.