Understanding Cell Exchange: Diffusion, Osmosis, and Energy Processes

1. Chapter 4 Section 1 Exchange within the Environment

2. Exchange with the Environment • A cell must be able to take in energy and get rid of wastes • The exchange of materials between a cell and its environment takes place at the cell membrane

3. Diffusion • Movement of particles from an area of high concentration to low concentration • Naturally spreading out

4. Diffusion • Can occur across cell membranes or outside the cell • No energy is needed

5. Examples • Tea in cup of hot water • Fragrance from a candle

6. Diffusion Demonstrations

7. Osmosis • The diffusion of water through the cell membrane • Pure water has the highest concentration (100%) • To lower concentration, something must be added to the water

8. Summarize the difference between diffusion and osmosis. • Diffusion is anything, Osmosis is water • In diffusion or osmosis, particles move from areas of _High__ concentration to areas of _Low_ concentration.

9. Thirsty for sea water? • Salt water has a low concentration of water and high concentration of salt. • The cells of your body have high concentration of water and low salt. • Which way will the water move?

10. Water from your cells will move from high to low concentration, leaving your cells and dehydrating you

11. Passive Transport • Occurs through the proteins embedded throughout the membrane • No energy used • Still moving high to low • Includes sugars and amino acids

12. Active Transport • Occurs through the proteins embedded throughout the membrane • Uses energy (ATP) • Occurs from LOW to HIGH • Example – nutrients brought into the roots of a plant

14. Endocytosis • Bringing large particles into the cell • Means “within the cell” • The cell membrane surrounds a particle and encloses it in a vesicle

15. Exocytosis • Taking things out of the cell • Means “outside the cell” • Vesicles are formed at the ER or Golgi and brought to the membrane to be released out of the cell

17. Cell Energy • Nearly all of the energy that fuels life comes from the sun

18. Photosynthesis • The process by which plants capture light energy from the sun and convert it into sugar • 6CO2 + 6H2O + light energy  C6H12O6 + 6O2

20. Pigments • Molecules in plant cells that absorb light energy • Chlorophyll is the main pigment for photosynthesis

21. 2 ways to release stored energy from food molecules • Cellular respiration • Fermentation

22. Cellular respiration • The process of releasing ATP in the cell from oxygen and glucose: producing carbon dioxide and water

24. Fermentation • The breakdown of sugars to make ATP in the absence of oxygen

25. Cellular respiration takes place in the mitochondria • C6H12O6 + 6O2 6CO2 + 6H2O + energy

26. Like the lungs but not quite • Relates to breathing in that both use oxygen and release carbon dioxide

27. 2 types of fermentation • In the muscles, producing lactic acid as a product • In bacteria and yeast, used in baking bread. The CO2 produced makes bread light and fluffy