BI110 Chapter Notes - Chapter 5: Membrane Transport Protein, Antiporter, Endoplasmic Reticulum
Document Summary
Active transport requires a direct or indirect input of energy derived from atp hydrolysis. Moves substances against their concentration gradients; requires cells to expend energy. Two kinds of active transport: primary active transport. The same protein that transports substance also hydrolyses atp to power transport directly: secondary active transport. Transport proteins do not break down atp. Instead use a favorable concentration gradient of substance, built up by primary active transport, as their energy source. Moves positively charged ions across membrane: h+ pumps (proton pumps) In the plasma membrane pushes hydrogen ions from the cytoplasm to the cellular exterior. Temporarily bind a phosphate group from atp during the pumping cycle: ca2+ pump. Pushes ca2+ from the cytoplasm to the cell exterior and from the cytosol into the vesicles of the endoplasmic reticulum. Ca2+ is typically high outside the cells and inside er vesicles. A regulatory control of cellular activities as diverse ass secretion, microtubule assembly, and muscle concentration: na+/k+ pump.
