2.5 Membrane Transport
Passive transport is diffusion of a substance across a membrane with no energy investment. Active transport uses energy to move solutes against their gradients. Bulk transport across the plasma membrane occurs by exocytosis and endocytosis.
To Think About:
How are molecules passively transported across a membrane? How are molecules actively transported across a membrane? How does active transport move molecules across the membrane? How are large molecules and large amounts of molecules transported across a membrane? Why are membrane proteins required for diffusion of certain molecules? How do large quantities of water move across the membrane? How do membranes become polarized? What molecules are necessary for active transport to occur? When is metabolic energy (such as ATP) needed for transport of molecules across the membrane? How does Na+/K+ ATPase contribute to membrane potential? How is water passively transported across a membrane?
Watch: AP Daily Video Membrane Transport
Answer the Following Questions:
- Passive transport is the movement of molecules from areas of____________________concentration to areas of____________________concentration____________________the use of metabolic energy.
- The two types of passive transport are _______________and_______________
- Explain two ways in which facilitated diffusion is different from diffusion.
- Active transport requires____________________to move molecules from areas of____________________concentration to areas of____________________concentration.
- List and describe the three types of endocytosis.
- What are some things the cell might secrete through the process of exocytosis?
Watch: AP Daily Video Facilitated Diffusion
Answer the Following Questions:
- Large quantities of water can pass through special membrane proteins called ______
- Active transport uses carrier proteins called _____ and help establish and maintain _______ ________
- ______ uses the energy from an electrochemical gradient to transport two different ions across the cell membrane. If the two ions are transported in the same direction, it is called ____, if the two ions are transported in opposite directions, it is called _______
- The movement of ions across the cell membrane may result in the creation of an __________ gradient. This gradient results in a membrane potential or voltage across the membrane.
- The sodium-potassium pump uses ATP to pump three ____ ions out of the cell for every two ______ ions it pumps into the cell. This creates a ______ _______.
- If ADH secretion is inhibited, what would be the result?
Watch: AP Daily Video Mechanisms of Transport
Answer the Following Questions:
- What is diffusion?
- How is facilitated diffusion different from regular diffusion?
- Large quantities of water use _________ to cross the cell membrane.
- Describe two ways in which active transport differs from passive transport.
- What are the three types of endocytosis? Use your textbook to find out how receptor mediated endocytosis differs from the other types of endocytosis.
- What is exocytosis? How do you think it might be used by the cell?
- How does the cell maintain a high concentration of sodium ions outside of the cell?
Supplementary Resources:
- Crash Course Biology: In Da Club—Membranes and Transport
- Bozeman Science: Mr. Andersen’s “Transport Across Cell Membranes” video
- Amoeba Sisters: Sodium Potassium Pump
- Nobel Prize in Chemistry, 2003: Peter Agre and Roderick MacKinnon, “for discoveries concerning channels in cell membranes.”
