Do Now: How is the cell membrane shown below like a colander? 11 - The Cell in Its Environment Do Now: How is the cell membrane shown below like a colander? Homework: The cell in its environment worksheet Mini Quiz Wednesday October 3rd. 2. Test on Wednesday, October 10th. .

Cell membrane is selectively permeable- some substances can pass through, while others cannot. Permeable to: oxygen, water, carbon dioxide Not permeable (impermeable) to: large molecules and salts

There are three methods by which substances move into and out of the cell: diffusion, osmosis or active transport

1) DIFFUSION: the process by which molecules move from an area of higher concentration to an area of lower concentration (high concentration--> low concentration) Demonstration: air freshener Example in text: page 41 unicellular organism in pond water..   -Molecules are always moving-they collide and push off each other until they are spread out evenly -Molecules diffuse through the cell membrane

Example in text: Page 42 red blood cell 2)OSMOSIS: diffusion of water molecules through a selectively permeable membrane, from high to low concentration. Demo: Raisins in water Example in text: Page 42 red blood cell

- The Cell in Its Environment 66 - The Cell in Its Environment

- The Cell in Its Environment 77 - The Cell in Its Environment Concentration of water is the same inside the cell as it is outside the cell What happened to the cell? It stays the same size

Concentration of water is lower outside the cell. 88 Concentration of water is lower outside the cell. What happened to the cell? It will shrink/shrivel

Concentration of water is higher outside the cell. 99 Concentration of water is higher outside the cell. What happened to the cell? It will expand or even explode

the movement of materials through a cell membrane using energy 3) ACTIVE TRANSPORT: the movement of materials through a cell membrane using energy (low  high concentration) - -Used when molecules need to move in the opposite direction then they would normally move by diffusion -Transport proteins can “pick up” molecules outside the cell and carry them in—this uses energy

The movement through a cell membrane without using energy is called passive transport The main difference between active transport and passive transport is: For active transport the cell must use energy. For passive transport the cell does not use energy.

12121212 - The Cell in Its Environment Active Transport takes materials from a low concentration to a high concentration. There are transport proteins that help this happen and these transport proteins require energy to work.

What will be on the test? Characteristics of Living Things Needs of Living Things The experiments: Is it a living thing lab, understand Redi and Pasteur concepts. Cell Theory Cells and their organelles Cell Transport (diffusion, osmosis and active transport)

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