“Active” Cellular Transport Requires energy cellular energy = ATP Moves materials from LOW to HIGH concentration Works AGAINST concentration gradient

Three Types of Active Transport Membrane Pumps 2. Endocytosis (pinocytosis and phagocytosis) 3. Exocytosis

1. Membrane Pumps Against gradient Uses transport proteins Specific binding sites Activated by ATP

The Membrane Pump ATP activates protein Molecules bind Transported to other side Protein returns to original shape Remember ATP is the energy used to power cellular reactions.

Membrane Pumps - Example The Plasma Membrane 11/12/2018 Membrane Pumps - Example Sodium-Potassium Pump Na+ (sodium ions) are pumped out and K+ (potassium ions) are pumped in against strong concentration gradients. G. Podgorski, Biol. 1010

Sodium-Potassium Pump The Plasma Membrane 11/12/2018 Sodium-Potassium Pump 3 Na+ are pumped in for every 2 K+ pumped out (both AGAINST the gradient). Creates a membrane potential and regulates cell volume G. Podgorski, Biol. 1010

2. Endocytosis Uses energy to form a vesicle by folding the membrane inward Moves food, large amounts of water, and other molecules to the inside of the cell

Receptor-Mediated Endocytosis The Plasma Membrane 11/12/2018 Receptor-Mediated Endocytosis Some integral proteins have receptors on their surface to recognize & take in hormones, cholesterol, etc. G. Podgorski, Biol. 1010

Two Types of Endocytosis Eating (Phagocytosis) Drinking (Pinocytosis) Takes in food Uses energy Takes in water/liquids Uses energy

Endocytosis – Phagocytosis The Plasma Membrane 11/12/2018 Endocytosis – Phagocytosis Used to engulf large particles such as food, bacteria, etc. into vesicles Called “Cell Eating” G. Podgorski, Biol. 1010

The Plasma Membrane 11/12/2018 Phagocytosis - Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue) G. Podgorski, Biol. 1010

Pinocytosis Most common form of endocytosis. The Plasma Membrane Pinocytosis 11/12/2018 Most common form of endocytosis. Takes in dissolved molecules as a vesicle. G. Podgorski, Biol. 1010

3. Exocytosis Cell expelling wastes Opposite of endocytosis Uses energy, against gradient

The Plasma Membrane 11/12/2018 Exocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane. Cell environment Inside Cell G. Podgorski, Biol. 1010

Review: Types of Transport Passive Diffusion Osmosis Facilitated diffusion Active Membrane pump Endocytosis Pinocytosis Phagocytosis Exocytosis