Cell transport involves the many ways that wastes and other materials get in and out of the cell.

Passive Transport

Passive transport is the movement of a substance across a cell membrane without the input of the cell's energy.

Simple Diffusion

Simple Diffusion involves the movement of atoms across the cytolemma from a region of higher concentration to a region of lower concentration.  Atoms move across the cell membrane by by going between the lipid molecules that make up the cell membrane.  Small atoms diffuse the easiest across the membrane.  No outside chemical energy is needed for simple diffusion.

Diffusion

Facilitated Diffusion

Diffusion is facilitated by cell membrane proteins that provide a way for atoms or molecules to more easily diffuse across the membrane.

Osmosis

Osmosis is the simple diffusion of water molecules across a semipermeable membrane.  It occurs when the concentration of solutes in the solution on the two sides of a semipermeable membrane are different moves from a solution with a higher water concentration to a solution with lower water concentration.

Active Transport

Chemical energy in the form of ATP is used to begin this process.  A membrane carrier is used and the direction can be from high to low concentration or from low to high concentration.  Active transport can enable a cell to move items across the membrane against a concentration gradient.

Active Transport

Exocytosis

In exocytosis wastes and cell products are packaged by Golgi apparatus in sacs called Golgi vesicles.  Gogi vesicles fuse with the cell membrane and the materials in the vesicles are secreted out of the cell.

Endocytosis

The cell membrane surrounds desirable macromolecules outside the cell.  The cell pinches off a saclike portion of its outer membrane to form a tiny new vesicle .  the vesicle moves into the cell where it releases its contents into the cytoplasm.

          Pinocytosis

In Pinocytosis the cell membrane encloses a droplet of fluid and its solutes and brings the droplet into the cell.

          Phagocytosis

In Phagocytosis the cell engulfs a food particle .  The vesicle containing food then fuses with a lysosome carrying digestive enzymes.

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