Presentation on theme: "Active Transport Active transport moves molecules across the cell membrane from an area of _______concentration to an area of ____________ concentration."— Presentation transcript:
Active Transport Active transport moves molecules across the cell membrane from an area of _______concentration to an area of ____________ concentration. Active transport requires ________ to move substances against their concentration _________________. Unlike ___________ transport, active transport requires cells to expend energy. Most often, the energy needed for active transport is supplied by ___________.
Cell Pumps Some types of active transport are performed by ____________ proteins called cell membrane _________. Sodium-Potassium Pump –The sodium-potassium pump moves _______ Na + ions into the cell’s external environment for every _________ K + ions it moves into the cytoplasm. –___________ supplies the energy that drives the pump.
Transport summary simple diffusion facilitated diffusion active transport ATP
4 Three Forms of Transport Across the Membrane
Transport of Large Particles Many substances, such as _________ and _________________, are too large to be transported by carrier proteins. Instead, they cross the cell membrane in ______________, which are membrane- bound sacs. The vesicle membrane is a ______ bilayer, like the cell membrane. Therefore, vesicles can _________ from the membrane, ________with it, or fuse with other _____________.
Endocytosis The movement of a large substance into a cell by means of a vesicle is called ________________. During endocytosis the cell membrane forms a pouch around the substance. The pouch then closes up and pinches off from the membrane to form a ________ inside the cell. Vesicles that form by endocytosis may fuse with _________ or other organelles. Endocytosis includes _____________, in which the vesicle contains solutes or fluids, and _________________, in which the vesicle contains large particles or cells.
Exocytosis Used to remove large particles from the cell. In __________, vesicles formed at the ______ or ________ fuse with the cell membrane, releasing their contents into the external environment. Cells use exocytosis to export ________ modified by the Golgi apparatus. Some protists release their _________ products through this process. Some cells also use exocytosis to remove bacteria or other microbes.
Wrapping It Up Both endocytosis and exocytosis require the input of __________. Cells maintain ______________ by moving substances into and out of the cell. Some transport processes require the input of energy (_________), while others do not (_____________). Together, the different types of transport allow a cell to interact with its environment while maintaining homeostasis.