Cell membrane and transport

Selective Permeability

The ability of a cell membrane to allow some substances to pass through while blocking others.

Diffusion

The movement of particles from an area of high concentration to an area of low concentration.

Osmosis

The diffusion of water across a selectively permeable membrane.

Passive Transport

The movement of substances across a membrane without using energy.

Concentration Gradient

The difference in concentration of a substance between two areas.

Tonicity

How a solution affects the movement of water into or out of a cell.

Isotonic

A solution with the same concentration of solutes as the inside of a cell, resulting in no net water movement.

Hypertonic

A solution with a higher concentration of solutes than the inside of a cell, causing water to leave the cell.

Hypotonic

A solution with a lower concentration of solutes than the inside of a cell, causing water to enter the cell.

Osmoregulation

The process by which cells or organisms regulate water and solute levels to maintain balance.

Plasmolysis

The shrinking of a plant cell's cytoplasm due to water loss when in a hypertonic solution.

Turgid

A plant cell that is swollen with water, providing firmness.

Flaccid

A plant cell that has lost water and becomes limp.

Facilitated Diffusion

The movement of substances across a membrane through protein channels without energy use.

Ion Channels

Proteins in the cell membrane that allow specific ions to pass through.

Gated Channels

Ion channels that open or close in response to specific signals.

Active Transport

The movement of substances across a membrane using energy (ATP), often against a concentration gradient.

Sodium-Potassium Pump

A protein that uses energy to pump sodium out of the cell and potassium into the cell.

Exocytosis

The process of moving large substances out of a cell by enclosing them in a vesicle.

Endocytosis

The process of bringing large substances into a cell by engulfing them in a vesicle.

Phagocytosis

A type of endocytosis where the cell engulfs large particles or cells.

Pinocytosis

A type of endocytosis where the cell takes in fluids and dissolved substances.