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Active Transport Active Transport • Active transport is the movement of molecules from an area of low concentration to high concentration • This takes molecules from outside the cell and moves them inside • These processes take energy Active Transport • There are two main types of active transport – Pumps – Vesicles • These two processes require energy and move molecules “up” a concentration gradient Cell Membrane Pumps • Membrane proteins can help both active and passive transport • Membrane proteins that assist active transport are referred to as Cell Membrane Pumps • These pumps assist charged particles into the cell Cell Membrane Pumps • These pumps are a little different than the passive transport carrier proteins • These have a certain amount of binding sites • These binding sites will fill with ions or other small molecules • Once those are full, the cell uses energy to move the molecules into or out of the cell Cell Membrane Pumps • The energy that is used by these pumps is ATP • ATP is a molecule that supplies energy when it is broken apart • After it is broken the cell can use the energy that is released Sodium Potassium Pump • One example of active transport in animal cells is the sodium potassium pump • This pump carries sodium and potassium up their concentration gradients Sodium Potassium Pump • Sodium is an element that can be toxic to a cell in high enough concentration • https://www.youtube.co m/watch?v=NTFBXJ3Zd_4 • Potassium is something that a cell needs for many processes however it is not always found in abundance in the environment Sodium Potassium Pump • The pump starts by binding three sodium atoms from inside the cell • With some energy, the sodium ions are released from the cell Sodium Potassium Pump • Next two potassium ions are attached to the protein pump • With some energy from ATP, the potassium ions are brought into the cell Movement in Vesicles • Many times there are molecules that are too large to fit through the carrier proteins and membrane pumps • These macromolecules, nutrients and molecules need to be brought into the cell in other ways Endocytosis • A cell can take in external fluid, large particles and dissolved particles • It does this by creating an indent in its cell membrane • The cell membrane then creates a small pouch called a vesicle • The vesicle is brought in to the golgi apparatus Endocytosis • When large molecules needs to be brought into the cell, the cell goes through endocytosis • Endocytosis is the process of making a vesicle out of cell membrane Endocytosis • What is actually in the vesicle determines what kind of endocytosis it is • Pinocytosis involves the movement and transport of solutes and fluids • Phagocytosis is the movement of large molecules, bacteria or viruses Endocytosis • Receptor–mediated endocytosis is a specific type of active transport that only happens when receptors on the cell surface pick up specific molecules • When the receptors engulf the molecules, a coated vesicle is formed and the cell can bring it where it needs to go Exocytosis • Exocytosis is the process by which a substance is released from the cell • Exocytosis is a process that requires energy to create the vesicles involved Exocytosis • During exocytosis a cell takes a vesicle and fuses it with its plasma membrane • During this process a cell releases what ever was contained within the vesicle • It can be a large molecule, several small molecules or things dissolved