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# Active Transport ## B2.1.7 Pump proteins for active transport Many substances needed by cells have to be absorbed from a weak external concentration. * **Define active transport** * from an area of low to high concentration * movement of particles * Against the concentration gradien...

# Active Transport ## B2.1.7 Pump proteins for active transport Many substances needed by cells have to be absorbed from a weak external concentration. * **Define active transport** * from an area of low to high concentration * movement of particles * Against the concentration gradient * using energy from ATP hydrolysis * And Specific Protein pumps * Across the semi-permeable membrane * **Write notes next to the diagrams below to describe what happens in active transport** **1.** Molecules or ions collide with the specific protein pump in the membrane. **2.** The protein pump is activated by ATP and uses energy released by the hydrolysis of ATP to change shape. **3.** The molecule or ions being transported are released on the other side of the membrane. **4.** Pi (inorganic phosphate from the hydrolysis of ATP to ADP and Pi) is released form the protein pump which causes it to revert back to its original shape, ready to receive another particle. **(Diagrams):** **(Image Descriptions):** The diagrams show a protein pump embedded in a cell membrane. There are four stages: * **Stage 1:** Molecules or ions are shown approaching the protein pump on one side of the membrane. * **Stage 2:** ATP binds to the carrier protein, changing its shape. * **Stage 3:** The molecule or ion is released to the other side of the membrane. * **Stage 4:** ADP and Pi are released, causing the protein pump to revert to its original shape, getting ready to bind to a new molecule or ion on the other side of the membrane.