ch18 Movement through Cell Membranes

A collection of vocabulary terms covering the biological processes of movement through cell membranes, including diffusion, active transport, and osmosis, as well as related environmental conditions and experimental materials.

Diffusion

The passive movement of a substance (solute) from an area of high concentration to an area of low concentration without the requirement of energy.

Concentration gradient

The difference between the concentrations of a solution in two areas.

Active transport

The movement of a substance from an area of low concentration to an area of high concentration across a semi-permeable membrane, using energy in the form of ATP against the concentration gradient.

Homeostasis

The process of maintaining the correct balance of substances in cells.

ATP (Adenosine triphosphate)

The form of energy required to power active transport.

Dialysis

A medical process used to remove toxic urea and maintain the balance of salts and water in the blood for patients awaiting a kidney transplant.

Osmosis

The passive movement of water from an area of high water concentration to an area of low water concentration across a semi-permeable membrane.

Semi-permeable membrane

A barrier that allows certain substances to pass through but not others.

Hypotonic solution

An external solution with a higher water concentration than that inside a cell, causing water to move into the cell.

Isotonic solution

An external solution with a water concentration equal to that inside a cell, resulting in no net movement of water.

Hypertonic solution

An external solution with a lower water concentration than that inside a cell, causing water to move out of the cell.

Lyse

The process of an animal cell bursting after too much water moves into it by osmosis.

Turgid

The state of a swollen plant cell when it experiences outward pressure (turgor) of the cytoplasm and cell membrane against the cell wall.

Flaccid

The state of plant cells in an isotonic solution, which makes the plant appear floppy and limp.

Plasmolysis

The shrinking of the contents of a plant cell away from the cell wall due to water loss in a hypertonic solution.

Surface area-to-volume ratio

A ratio that is higher in smaller cells, allowing materials to diffuse throughout the cell quickly.