Starter

1. Starter • What is the function of the cell membrane? • What types of macromolecules make up the cell membrane? • How can the membrane be damaged?

2. Cell Membranes

3. Cell Membrane • All living things are surrounded by a membrane. • The cell membrane controls exchange of materials such as nutrients and waste between cells and their environment. • Has other important functions (eg. Receive hormones).

4. Opposing Neurons Nerve cell Gap between cells Cell Membrane Cell Membrane 7nm wide Nerve cell

5. Cell Membrane

6. Cell Membrane • Consists of two layers of lipids (lipid bilayer). • One lipid includes a hydrophilic (water-loving) head and hydrophobic (water-hating) tails.

7. Lipid Lipid Bi-layer Cell Membrane

8. Semi-Permeable Membrane • Proteins in the membrane allow nutrients, oxygen, and water into the cell and waste products out of the cell. • These proteins also limit other molecules from entering or leaving the cell.

9. Cell Membranes • Membranes can be destroyed by anything that destroys a protein or fat (eg. heat or fat solvents)

10. Cell Membranes • Substances move across a membrane in two ways. • Passive Transport • Active Transport

11. Passive Transport • Passive transport involves the movement of biochemicals or molecules across membranes without the use of chemical energy. • Passive transport is dependent on the permeability of the cell membrane.

12. Passive Transport

13. Diffusion 95% • Diffusion is the movement of molecules from an area of high concentration to an area of low concentration. • The difference in concentration between the two areas is called the concentration gradient. 65% 95% 90%

14. Diffusion

15. Try This Starch & Glucose Solution Iodine Solution

16. Diffusion • The rate of diffusion varies depending on: • The size of the molecules • Smaller move faster. • The temperature • Warmer moves faster.

17. Diffusion • The rate of diffusion varies depending on: • The state of the matter diffusing • Gases move faster. • The concentration of the chemical • Steep gradients move faster.

18. Osmosis • Osmosis is the net movement of water from an area of high concentration to an area of low concentration through a semi-permeable membrane.

19. Osmosis • If you have a 5% salt solution and a 10% salt solution, the 5% solution has the highest concentration of water. • The water would move from the 5% solution to the 10% solution through a membrane until the solutions were the same.

20. Osmosis • A very weak solution is called hypotonic (hypo – too little). • A very strong solution is called hypertonic (hyper – too much). • If the solutions have the same water concentration, they are called isotonic (iso – the same).

21. Hypotonic Sucrose Solution Hypertonic Sucrose Solution Semi-permeable Membrane

22. Isotonic Sucrose Solutions Semi-permeable Membrane

23. Osmoregulation • Osmoregulation is the process by which organisms keep the water concentration in their cells relatively constant.

24. Isotonic Solution Hypotonic Solution Hypertonic Solution Lysed Shrivelled Normal

25. Osmoregulation in Animal Cells Shrivelled Normal Lysed

26. Osmoregulation in Plant Cells

27. Facilitated Diffusion • Certain proteins in the membrane allow specific chemicals to pass through faster that simple diffusion. • Eg. Oxygen and Glucose.

28. Active Transport • Active transport is an energy-requiring process that moves material across a cell membrane and up the concentration gradient (from an area of low concentration to an area of high concentration).

29. Active Transport