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Transcript
3.2.1.1a and 3.2.1.2a Transport Within Cells Everything that moves into or out of a cell must go through the cell membrane. The cell membrane is made of two layers of lipid molecules with proteins embedded. If the molecules are small and nonpolar, they may be able to move between the lipid molecules to enter or leave the cell. When molecules move from an area of higher concentration to an area of lower concentration across the membrane, it is called diffusion. It occurs without the cell spending any energy. When water diffuses through the cell membrane, it is called osmosis. Some molecules can diffuse through membrane proteins. These molecules are too large to move between the lipid molecules, but can move through special channels inside the membrane protein. This is called facilitated diffusion. Diffusion, osmosis, and facilitated diffusion all require no energy from the cell. Together, they are referred to as passive transport. Sometimes a cell must force molecules in or out of the cell, and use energy to do it. When a cell uses energy to move something across its membrane, it is called active transport. Some membrane proteins are built to help move molecules from a low concentration toward a high concentration. These proteins are called carrier proteins. Molecules bind to them. Then ATP molecules bind to them. The ATP is used to change the shape of the protein so that the molecule is moved through to the other side. Sometimes a cell must use vessicles to move a great number of molecules across the membrane at once. The processes called endocytosis and exocytosis both use vessicles to transport molecules in great quantities. Endocytosis occurs when the cell membrane is wrapped around some large particle outside of the cell. For example, an amoeba obtains food by endocytosis. Exocytosis occurs when a vessicle fuses with the cell membrane. The vessicles contents are dumped to the outside of the cell as the vessicle membrane becomes fused with the cell membrane. Vessicles that are used in exocytosis might contain wastes. They might also contain a substance, like adrenalin, that is used outside of the cell. Matching _____1. diffusion a. the movement of substances out of a cell using vessicles _____ 2. osmosis b. movement of substances across the cell membrane using energy _____ 3. facilitated diffusion c. the movement of a substance from an area of high concentration to an area of low concentration _____ 4. passive transport d. the movement of substances into a cell using vessicles _____ 5. active transport e. diffusion of molecules through special protein channels _____ 6. carrier proteins f. the diffusion of water _____ 7. endocytosis g. the movement of substances into or out of a cell without using energy _____ 8. exocytosis h. proteins that move molecules from an area of low concentration to an area of high concentration True or False _____ 1. Everything that moves into or out of a cell must go through the cell membrane. _____ 2. Molecules cannot move between the lipid molecules in a cell membrane. _____ 3. Small, nonpolar molecules can move between the lipid molecules in a cell membrane. _____ 4. A cell membrane is made of three layers of lipid molecules with proteins embedded. _____ 5. A cell membrane is made of two layers of lipid molecules with proteins embedded. _____ 6. Diffusion occurs when molecules move from an area of high concentration to an area of low concentration. _____ 7. Diffusion occurs when molecules move from an area of low concentration to an area of high concentration. _____ 8. Diffusion occurs only when the cell uses energy. _____ 9. Diffusion occurs without the cell using energy. _____ 10. Osmosis is the diffusion of water. Fill in the Blank - One word may be used twice. passive transport high concentration facilitated diffusion proteins diffusion low concentration large osmosis lipids small 1. A cell membrane is made of two layers of ______________ with _______________ embedded. 2. If molecules are _____________ and nonpolar, they may be able to move between the lipid molecules. 3. If molecules are ________________ , they may be able to move through ____________ in the cell membrane. This process is called ______________________. 4. _____________________ is the movement of molecules from an area of _______________________________ to an area of ___________________________. 5. _____________________ is the diffusion of water through a cell membrane. 6. Diffusion, osmosis, and facilitated diffusion are called ________________________ because none of these processes requires energy. True or False _____ 1. Passive transport occurs when a cell uses energy to move something across its membrane. _____ 2. Active transport occurs when a cell uses energy to move something across its membrane. _____ 3. Carrier proteins move molecules from an area of high concentration to an area concentration. _____ 4. Carrier proteins move molecules from an area of low concentration to an area concentration. _____ 5. Endocytosis uses vessicles to help move many molecules at once from the of a cell to the outside. _____ 6. Endocytosis uses vessicles to help move many molecules at once from the of a cell to the inside. _____ 7. Exocytosis uses vessicles to help move many molecules at once from the of a cell to the outside. _____ 8. Exocytosis uses vessicles to help move many molecules at once from the of a cell to the inside. ____ 9. Endocytosis may be used to remove wastes from a cell. ____ 10. Exocytosis may be used to remove wastes from a cell. ____ 11. An amoeba uses endocytosis to obtain food. ____ 12. An amoeba uses exocytosis to obtain food. of low of high inside outside inside outside Fill in the Blank endocytosis active low concentration exocytosis carrier proteins energy vessicles high concentration adrenalin 1. Sometimes a cell must expend ___________ to move molecules in or out of a cell. . 2. In the cell membrane, _____________________ will change shape when they bind to specific molecules and to ATP. 3. This is an example of __________ transport. 4. Endocytosis and exocytosis are forms of transport that require ________________. 5. ____________________ occurs when a vessicle fuses with the cell membrane and dumps its contents outside of a cell. 6. ______________________ is an example of a substance that is released by exocytosis. 7. ______________________ occurs when a cell membrane encloses a substance outside of the cell and then brings the substance into the cell in the form of a vessicle. 8. A cell must expend energy when it must move substances from a _________________________ to a ___________________________. Answer the Following 1. Describe the composition of a cell membrane. 2. What is diffusion? 3. What is osmosis? 4. What is facilitated diffusion? 5. What is the difference between passive transport and active transport? 6. What is a carrier molecule? 7. What is endocytosis? 8. What is exocytosis?