Active Transport Using energy

Active Transport Transport methods that involve work (energy) by the cell are forms of active transport.

Carrier molecules are proteins in the cell membrane that transport large molecules or molecules that cannot dissolve in the lipids that make up the cell membrane. They pick up molecules on one side of the membrane and move them to the other side.

2 Kinds of Carrier Transport 1.facilitated diffusion - substances move with the concentration gradient Carrier proteins speed things up passive transport because energy is not used ex: glucose

2. active transport - involves the movement of materials against the concentration gradient requires the use of cellular energy Ex: Na+ – K+ pump

Bulk Transport Movement in Vesicles

Endocytosis and exocytosis are active processes that enable cells to take in or release materials too large to pass through the membrane. Molecules enter or exit through a vesicle. endocytosis exocytosis

Endocytosis Large molecules, such as protein, enter the cell when they are surrounded by the cell. This forms a vesicle for the transport of these molecules. This process is called endocytosis.

Phagocytosis “ cell eating ” Solid particles enter through a vesicle ex: amoeba taking in food ex: white blood cells eating bacteria

Pinocytosis “ cell drinking ” Particles enter as a droplet (liquid) Ex: human egg cell absorbs nutrients Ex: absorption of nutrients by cells in the intestines

Exocytosis When large particles leave the cell, they use a vesicle that fuses with the cell membrane. The releasing of these molecules is called exocytosis.

ex: secretion of proteins by a cell

The End