Ch 3 The Cell - Movement Into/Out of Cells

Diffusion does NOT require ______ to move substances across cell membrane.

ATP / energy

Facilitated diffusion

-Requires protein channel to move large substance across membrane but does NOT require ATP (energy)
-Moves substance from area of high concentration --> low
concentration

Diffusion

-does not require ATP / energy
-moves substance from area of high concentration --> low concentration

Active Transport

-moves substance from area of low concentration --> high concentration
-requires presence of protein channel to "pump" substance from low to high concentration
-requires ATP (energy)

Endocytosis (Endo = into, Cyto = cell)

-moves substances INTO cell that are too big to pass through protein channels or diffuse through phospholipid bilayer
-substance is engulfed/surrounded by cell membrane instead of crossing cell membrane.
-Ends up inside cell in vesicle made of cell membrane
-process requires ATP / energy

Pinocytosis

-Form of Endocytosis, requires ATP (energy)
-Liquid moves into cell and ends up in vesicle inside cell
-Cell drinks (Pino = Drink, cyte = cell)

Phagocytosis

-Form of Endocytosis; process requires ATP (energy)
-Solid moves into cell and ends up inside cell in a vesicle made of cell membrane.
-Cell eats (Phago = Eat, cyte = cell)
-Example: bacteria entering White Blood Cell

Receptor-mediated Endocytosis

-Substance attaches to a receptor on cell membrane.
-Cell engulfs the substance and the receptor. They move into cell inside a vesicle made of the cell membrane.
-Process requires ATP (energy)

Exocytosis

-moves substances OUT of cell that are too big to diffuse across phospholipid bilayer or pass through protein channel
-substance in vesicle inside cell is released out of cell when vesicle fuses to inner surface of cell membrane and opens to outside
-process requires ATP (energy)

Transcytosis

-Involves both Endocytosis AND Exocytosis
-Substance enters one side of cell thru Endocytosis, moves across cell, and exits other side of cell thru Exocytosis.
Trans = across, Cyte = cell