Active Transport Cell Membrane Pumps and Vesicle Transport

Active Transport Cell Membrane Pumps and Vesicle Transport

Active Transport § Active transport - movement of materials AGAINST the concentration gradient from low concentration to high concentration Ø Requires the cell to use energy (ATP) Ø 2 kinds: 1. membrane pumps 2. vesicle transports

1. Cell Membrane Pumps Ø Involve carrier proteins called cell membrane pumps to move materials against the concentration (UP concentration gradient) ØSimilar to the steps of facilitated transport. Ø Results in electrical impulses across nerve cells ØEx. Sodium-Potassium Pump

2. Vesicle Transport Ø Some substances (ex. Food) are too BIG to pass through membrane OR large quantities need to pass through the cell Ø These situations use vesicle transport Ø Two kinds 1. Endocytosis 2. Exocytosis

Endocytosis Ø Cells ingest external fluid, macromolecules & large particles (including other cells) Ø External materials are enclosed by part of the cell, forming a pouch Ø The pouch pinches off cell membrane & becomes a membrane bound organelle called a vesicle Ø Vesicles can fuse with lysosomes to digests contents. Two kinds of Endocytosis: 1. Phagocytosis – movement of large particles or whole cells. *Possible feeding method, or a method of defense to destroy bacteria/viruses 2. Pinocytosis – transport of solutes or liquids

Phagocytosis (cartoon animation) Pinocytosis (cartoon animation)

Phagocytosis (taking place in cells under a microscope)

Endocytosis

Exocytosis (Reverse of endocytosis) Ø Vesicles in cytoplasm fuse with cell membrane and RELEASE their contents into the external environment OUTSIDE the cell Ø Used to release large molecules such as proteins packaged by the golgi apparatus Ø Used in nervous & endocrine system to control activities in other cells.

Exocytosis

Endocytosis & Exocytosis

Endocytosis • http: //www. maxanim. com/physiology/Endo cytosis%20 and%20 Exocytosis/Endocytosi s%20 and%20 Exocytosis. htm