1. 7-3: Cell Boundaries
Biology 1

2. All cells are surrounded by a thin, flexible barrier
Introduction
All cells are surrounded by a thin, flexible barrier
CELL MEMBRANE: thin, flexible barrier around a cell; regulates what enters and leaves the cell
Plant cells are also supported by a strong layer
CELL WALL: strong supporting layer around the cell membrane in plants, algae, and some bacteria

3. Cell Membrane
Cell membrane regulates what enters and leaves the cell, also provides protection and support
Cell membranes are made from double-layered sheets
LIPID BILAYER: double-layered sheet that forms the core of nearly all cell membranes

5. Cell walls are present in plants, algae, fungi and prokaryotes
Main function is to provide support and protection
Made of mostly carbs and proteins

6. Diffusion
Most important function of cell membrane is to move molecules from one side to other
DIFFUSION: process by which molecules tend to move from an area where they are more concentrated to an area where they are less concentrated

7. Particles move back and forth across cell membrane
Diffusion
Particles move back and forth across cell membrane
Particles continue moving until they are equal everywhere
EQUILIBRIUM: when the concentration of a solute is the same throughout a solution
When perfume is sprayed in one corner, then the whole room smells

8. The movement of water through the membrane of a cell
Osmosis
The movement of water through the membrane of a cell
OSMOSIS: diffusion of water through a selectively permeable membrane

9. Water wants to move to where there is LESS
Osmosis
Water wants to move to where there is LESS
ISOTONIC: when the concentration of two solutions is the same
HYPERTONIC: when comparing two solutions, the solution with the greater concentration of solutes
HYPOTONIC: when comparing two solutions, the solution with the lesser concentration of solutes

11. Facilitated Diffusion
Some molecules (like sugar) pass through cells very quickly
Cell membranes have “helper” proteins that allow certain molecules to cross
ONLY allow specific molecule (like sugar) to pass through)
FACILITATED DIFFUSION: movement of specific molecules across cell membranes through protein channels

12. Cell Membrane Passive Transport
Great Pacific Media
Cell Membrane Passive Transport