1. 3.3 Cell Membrane TEKS 3E, 4B, 9A KEY CONCEPT The cell membrane is a barrier that separates a cell from the external environment.

2. 3.3 Cell Membrane TEKS 3E, 4B, 9A Cell membranes are composed of two phospholipid layers.

3. 3.3 Cell Membrane TEKS 3E, 4B, 9A Cell membranes are composed of two phospholipid layers. The cell membrane has two major functions. cell membrane

4. 3.3 Cell Membrane TEKS 3E, 4B, 9A Cell membranes are composed of two phospholipid layers. The cell membrane has two major functions. – –forms a boundary between inside and outside of the cell cell membrane outside cell inside cell

5. 3.3 Cell Membrane TEKS 3E, 4B, 9A Cell membranes are composed of two phospholipid layers. The cell membrane has two major functions. – –forms a boundary between inside and outside of the cell – –controls passage of materials cell membrane outside cell inside cell

6. 3.3 Cell Membrane TEKS 3E, 4B, 9A Cell membranes are composed of two phospholipid layers.

7. 3.3 Cell Membrane TEKS 3E, 4B, 9A cell membrane Cell membranes are composed of two phospholipid layers. The cell membrane is made of a phospholipid bilayer.

8. 3.3 Cell Membrane TEKS 3E, 4B, 9A cell membrane Cell membranes are composed of two phospholipid layers. The cell membrane is made of a phospholipid bilayer. There are other molecules embedded in the membrane. protein cholesterol protein carbohydrate chain protein channel

9. 3.3 Cell Membrane TEKS 3E, 4B, 9A cell membrane Cell membranes are composed of two phospholipid layers. The cell membrane is made of a phospholipid bilayer. There are other molecules embedded in the membrane. The fluid mosaic model describes the membrane. protein cholesterol protein carbohydrate chain protein channel

10. 3.3 Cell Membrane TEKS 3E, 4B, 9A Fluid Mosaic Model The cell membrane is flexible (moves like a fluid) The variety of molecules making up the membrane makes it look like a mosaic

11. 3.3 Cell Membrane TEKS 3E, 4B, 9A Cell membranes are composed of two phospholipid layers.

12. 3.3 Cell Membrane TEKS 3E, 4B, 9A Cell membranes are composed of two phospholipid layers. The cell membrane is selectively permeable. Some molecules can cross the membrane while others cannot.

13. 3.3 Cell Membrane TEKS 3E, 4B, 9A Cell membranes are composed of two phospholipid layers. The cell membrane is selectively permeable. Some molecules can cross the membrane while others cannot.

14. 3.3 Cell Membrane TEKS 3E, 4B, 9A Phospholipids glycerol Charged phosphate group (Hydrophilic = water loving) two fatty acid chains (Hydrophobic = water hating)

15. 3.3 Cell Membrane TEKS 3E, 4B, 9A cell membrane integral protein cholesterol peripheral protein carbohydrate chain protein channel

16. 3.3 Cell Membrane TEKS 3E, 4B, 9A Chemical signals are transmitted across the cell membrane. Receptors bind with ligands and change shape. There are two types of receptors.

17. 3.3 Cell Membrane TEKS 3E, 4B, 9A Chemical signals are transmitted across the cell membrane. Receptors bind with ligands and change shape. There are two types of receptors. – –intracellular receptor

18. 3.3 Cell Membrane TEKS 3E, 4B, 9A Chemical signals are transmitted across the cell membrane. Receptors bind with ligands and change shape. There are two types of receptors. – –intracellular receptor – –membrane receptor