Bio- Chapter 3

Plasma Membrane

The membrane that separates the inside and outside of a cell.

Fluid Mosaic Model

shows the plasma membrane as a flexible mix of parts with different jobs.

Semi-permeable

lets certain substances in and keeps others out.

Phospholipid Bilayer

forms the plasma membrane and controls what enters and exits.

Amphipathic

A molecule that has both hydrophilic (water-attracted) and hydrophobic (water-repelling) parts.

Facilitated Diffusion

when molecules move passively through membrane proteins.

Osmosis

the movement of water from low to high solute concentration.

Hypertonic Solution

higher solute concentration compared to another solution, causing water to move out of cells placed in it.

Hypotonic Solution

Lower solute concentration outside the cell causes water to move into the cell

Isotonic Solution

has equal solute concentrations, so no water moves.

Active Transport

The movement of substances against their concentration gradient, requiring energy.

Sodium-Potassium Pump

A protein pump that transports sodium out of the cell and potassium into the cell against their concentration gradients.

Exocytosis

The process of exporting materials out of a cell via vesicles.

Endocytosis

The process of importing materials into a cell by engulfing them in vesicles.

Phagocytosis

A type of endocytosis where the cell engulfs large particles or cells, often for digestion.

Pinocytosis

A type of endocytosis where the cell engulfs extracellular fluid and dissolved molecules.