Active and Passive Transport

Passive and Active Transport This refers to the movement of molecules across a membrane. Passive = no energy needed Active = energy needed

Facilitated Diffusion Passive Transport No energy needed so this occurs due to Concentration gradients. Kinds… Osmosis Simple Diffusion Facilitated Diffusion Endocytosis Exocytosis

Passive Transport 1. Osmosis and Simple Diffusion are the least complicated of the different Passive Transports.

Facilitated Diffusion Facilitated Diffusion is when there is a special channel made of proteins in the membrane large enough for a specific molecule to pass through.

Channel and Carrier Proteins Channel Proteins- are pores in the cell membrane made by proteins. These pores are big enough for large molecules like sugar to pass through on their own. (an open door) Carrier Proteins- Grab on to only certain molecules and will then change shape to let them into the cell. (Like a bouncer opening a club door)

Channel and Carrier Proteins

Endocytosis Cells Eating! When cells fold the membrane around food or liquid, trapping it in little bubbles of membrane and bring it into the cell.

Exocytosis Cells POOPING!!! Waste in the cell collects in lysosome, where it is digested. Then their membrane connects to the cell membrane, and dumps out the waste. (poop)

Active Transport *The energy needed for active transport is gained from ATP made in the mitochondria.

Active transport is used to: 1. Generate charge gradients. For example, within the mitochondria, hydrogen ion pumps move hydrogen into the inter-membrane space of the organelle as part of making ATP. The energy used in these pumps is made again by the organelle.

Example: Sodium Potassium Pump. Makes muscles move.

2. Concentrate ions Keep the good minerals and nutrients inside the cell that are in low concentration outside. 

3. Keep unwanted ions or other molecules out of the cell that are able to diffuse through the cell membrane. 

In all these cases the key is that active transport uses energy to send substances against the direction they would travel by simple diffusion: that is from a region of low concentration to a region of high concentration. 

Active Transport