1. The Cell in Its Environment Chapter 3, Section 4

2. Vocabulary Selectively Permeable – a property of a cell membrane that allows some substances to pass through, while others cannot (Screen door) Selectively Permeable – a property of a cell membrane that allows some substances to pass through, while others cannot (Screen door) Diffusion – process by which molecules move from an area of higher concentration to an area of lower concentration Diffusion – process by which molecules move from an area of higher concentration to an area of lower concentration Osmosis – diffusion of water molecules Osmosis – diffusion of water molecules

3. Passive Transport – movement of materials through the cell membrane without using the cell’s energy Passive Transport – movement of materials through the cell membrane without using the cell’s energy Active Transport – movement of materials through the cell membrance using cell’s energy Active Transport – movement of materials through the cell membrance using cell’s energy

4. Gold Keys Diffusion is the main method by which small molecules move across the cell membrane Diffusion is the main method by which small molecules move across the cell membrane Because cells cannot function properly without adequate water, many cellular processes depend on osmosis Because cells cannot function properly without adequate water, many cellular processes depend on osmosis Active transport requires the cell to use its own energy, while passive transport does not Active transport requires the cell to use its own energy, while passive transport does not

5. General Notes Diffusion, Osmosis and Active Transport are the 3 methods in which materials can move in and out of cells Diffusion, Osmosis and Active Transport are the 3 methods in which materials can move in and out of cells Diffusion happens because the more crowded molecules are the more they bump into each other causing them to move apart (to lower concentrated areas) Diffusion happens because the more crowded molecules are the more they bump into each other causing them to move apart (to lower concentrated areas) With Osmosis molecules will move into or out of the cell With Osmosis molecules will move into or out of the cell

6. Transport Proteins are the “gate keepers”. They pick up molecules outside the cell and bring them into the cell Transport Proteins are the “gate keepers”. They pick up molecules outside the cell and bring them into the cell Active Transport happens when a cell takes in a substance that is in higher concentration inside the cell (greedy – the cell already has plenty but is going to take in even more) Active Transport happens when a cell takes in a substance that is in higher concentration inside the cell (greedy – the cell already has plenty but is going to take in even more) Cells can engulf, surround, a particle – also Active Transport Cells can engulf, surround, a particle – also Active Transport Cells are so small because it would be too difficult to transport material through the cytoplasm if it were larger. (raft in a pool vs raft in the ocean) Cells are so small because it would be too difficult to transport material through the cytoplasm if it were larger. (raft in a pool vs raft in the ocean)