Active Transport

Joohee KimSec. IIIIB Biology

Active Transport Active transport

is the pumping of molecules against their concentration gradient with the expenditure of energy (ATP).

Why Is It Necessary?

Living cells often require the uptake of molecules that are scarce in their environment.

3 Types Of Active Transport

Ion Pumps Cotransport Endocytosis

Ion Pumps Ion pumps (also

called electrogenic pumps) are special proteins which actively transport ions resulting in an ionic and voltage gradient.

Cotransport

Cotransport is the coupled passage of two materials across a membrane.

Without assistance, the sucrose is unable to enter the cell.

Endocytosis

Endocytosis is the import of materials to the cell by infoldings of the plasma membrane.

Phagocytosis (cell eating) In Phagocytosis,

pseudopods (extensions of the cell membrane) surround the food item and fuse together forming a vesicle to take the food into the cell.

Pinocytosis (cell drinking)

In Pinocytosis, vesicles of fluid are formed in the cell membrane without the formation of pseudopods.

Receptor-Mediated Endocytosis In receptor-

mediated Endocytosis, special coated pits in the cell membrane are lined with receptor proteins that binds with specific materials.