Module 6: Transport Mechanisms of Cells

Vocabulary flashcards covering cellular transport mechanisms, including passive transport, active transport, bulk transport, and solution tonicity.

Passive Transport

A naturally occurring phenomenon in which the cell does not require energy for molecules to move.

Diffusion

The movement of particles along a concentration gradient from high to low concentration.

Osmosis

The movement of water through a partially permeable membrane from high to low concentration.

Active Transport

The movement of particles against a concentration gradient from low to high concentration, which requires energy.

Isotonic Solution

A solution that has the same osmolarity (concentration of solutes) as another solution, resulting in equal water flow into and out of the cell with no net movement.

Hypertonic Solution

A solution containing a higher concentration of solutes compared to another solution, causing water to move out of the cell and reducing or shrinking the cell's size.

Hypotonic Solution

A solution containing a lower concentration of solutes compared to another solution, causing water to move into the cell and making it swell or burst.

Plasmolysis

The shrinking of the protoplasm away from the cell wall in plants and bacteria as a result of water leaving the cell.

Cytolysis

The bursting of animal cells when water moves toward and fills the cell in a hypotonic solution.

Facilitated Diffusion

A passive transport process driven by concentration gradients that utilizes protein transmembrane channels or carrier proteins to move specific materials into or out of the cell.

Bulk Transport

The transport of macromolecules like proteins and polysaccharides into and out of the cell that involves energy expenditure in the form of ATP.

Exocytosis

A bulk transport process where secretory vesicles fuse with the plasma membrane to export materials, wastes, or cellular products like enzymes and hormones out of the cell.

Endocytosis

The bulk transport process by which materials enter the cell.

Phagocytosis

Also known as cell-eating, a form of endocytosis where the cell's plasma membrane surrounds a macromolecule or cell to form a food vacuole or phagosome.

Pinocytosis

Also known as cell-drinking, a form of endocytosis where a cell engulfs droplets of fluid by pinching in and producing vesicles smaller than phagosomes.

Receptor-mediated Endocytosis

A highly selective endocytosis mechanism for bringing materials into the cell, mediated by receptor proteins located in depressed membrane regions called coated pits.

Alveoli

Air sacs in the lungs that act as the site for gas exchange where oxygen diffuses into the blood and carbon dioxide diffuses into the air sacs to be exhaled.

Epidermis

The outer layer of skin that absorbs water and swells when soaked.