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Active Transport Sometimes a cell must move particles from a region of lesser to a region of greater concentration. To do so the cell must use energy to counteract the random motion of the particles. The cell plays an active role and does work. Because the cell’s energy is required to move the particles, this type of movement is called active transport. Active transport also involves permease molecules. Permeases involved in active transport are known as pumps. Energy from the cell is used to change the shape of the pump. The change in shape results in pulling a particle into (or pushing it out of) a cell.

A cell can rid itself of harmful particles by active transport. For example, some cells of the kidney actively transport wastes out Waste materials must be removed. Some wastes would poison an organism. Active transport maintains a greater concentration of the waste materials outside the kidney cells than inside the cells. Active transport also may work to bring extra particles into the cell. For example, root cells of plants bring in and retain needed mineral ions from the soil. Even though there may be more ions in the transport. Use of energy by these cells prevents the natural diffusion of these ions out of the cells แหล่งข้อมูล: BIOLOGY living systems. Page 71-72.

โดย : นาง ปรียา ชมเชี่ยวชาญ, ศรีปทุมพิทยาคาร, วันที่ 2 กรกฎาคม 2545