Active Transport MOVING MOLECULES ACROSS THEIR CONCENTRATION GRADIENT

Active Transport Moving molecules against their concentration gradient is known as Active Transport.  Energy is required because molecules are being pumped against their concentration gradient  Proteins that work as pumps are called protein pumps.  These protein pumps are membrane bound receptors.

Moving Against the Concentration Gradient The cell uses energy in the form of ATP to transport molecules across the membrane. Low High What is ATP?

ATP- Adenosine Triphosphate Breaking off one of the three phosphates creates energy to be used by the cell. ATP ADP+ P + Energy

Sodium-Potassium Pump  Antiporter- membrane transport protein that simultaneously transports two different molecules across a membrane in opposite directions.  3 Na+ out of cell / 2 K+ into cell  Major contributor for (-) resting membrane potential Requires Energy

Proton Pump  Uses ATP energy to pump Hydrogen molecules across the cell membrane  Aids in membrane potential being slightly (-) Requires Energy

Endocytosis A process by which cells ingest external fluid, macromolecules, and large particles. Vesicles- membrane bound organelle Pinocytosis - involves transport of solutes or fluids. Phagocytosis - involves transport of large particles. Requires Energy

Exocytosis A process that moves intracellular vesicles outside the cell. Proteins are made in ribosomes, packaged in the Golgi apparatus and then transported to the cell surface by vesicles. Requires Energy

Homeostasis  The tendency of an organism or cell to maintain internal stability.  What does membrane transport have to do with homeostasis?

Negative Feedback  Release of an initial hormone stimulates release or production of other hormones or substances that inhibit further release of the initial hormone.  Most hormone systems use negative feedback  Ex. Thermostat

Positive Feedback  Release of an initial hormone stimulates release or production of other hormones.