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Bio Vocab List 2.3
| Term | Definition |
|---|---|
| Cell Membrane | Surrounds all cells and controls what comes in and goes out |
| Semi-permeable | Allows some molecules through but not others |
| Phospholipid bilayer | Structure of the cell membrane. Polar heads are hydrophilic and non-polar tails are hydrophobic. |
| Diffusion | Molecules move across a membrane from high to low concentration. No energy needed. |
| Carrier-facilitated diffusion | Molecules are "helped" across a membrane by proteins from high to low concentration. No energy needed. |
| Active transport | Molecules are "pumped" across a membrane by proteins from low to high concentration. Energy is required! |
| ATP | Type of energy that the cell uses. |
| Concentration | Amount of molecules in a given area/volume. |