3. CHAPTER 8 Cellular Energy

4. 8-1 How Organisms Obtain Energy

5. JOURNAL  What are some of the different forms of energy?  What do organisms need energy for?

6. Launch Lab: How is Energy Transformed?  Page 216  The flow of energy in living systems is driven by a variety of chemical reactions and chemical processes. Energy is transformed from the Sun’s radiant energy to chemical energy to other forms of energy along the way. In this lab, you will observe two processes in which energy is transformed.

7. Transformation of Energy  Energy is the ability to do work. Cellular Energy  Thermodynamics is the study of the flow and transformation of energy in the universe.

8. Laws of Thermodynamics  First law “Law of Conservation of Energy” energy can be converted from one form to another, but it cannot be created nor destroyed.  Example: Stored energy in food is converted to chemical energy when you eat, and then mechanical energy when you kick a ball.

9. Laws of Thermodynamics  Second law “Entropy increases” energy cannot be converted without the loss of usable energy.  Energy that is “lost” is usually converted to thermal energy  Example – energy lost in food chains Entropy is the measure of disorder, or unusuable energy, in a system

10. Autotrophs and Heterotrophs  Autotrophs are organisms that make their own food.  Heterotrophs are organisms that need to ingest food to obtain energy.

11. Metabolism All of the chemical reactions in a cell  Catabolic Pathways – Release energy by breaking down large molecules into smaller molecules  Anabolic Pathways - Use the energy released by catabolic pathways to build larger molecules from smaller molecules Result in the continual flow of energy in an organism

12. ANABOLIC PATHWAY Photosynthesis light energy from the Sun is converted to chemical energy for use by the cell CATABOLIC PATHWAY Cellular respiration organic molecules are broken down to release energy for use by the cell

13. Metabolic Pathway Series of chemical reactions in which the product of one reaction is the substrate for the next reaction Photosynthesis (autotrophs) Cellular Respiration (heterotrophs & autotrophs)

14. A denosine T ri p hosphate  The cell’s key to being able to store and release energy ATP: The Unit of Cellular Energy

15.  ATP releases energy when the bond between the second and third phosphate groups is broken, forming a molecule called adenosine diphosphate (ADP) and a free phosphate group. ATP

16.  ATP can easily release and store energy by breaking and re-forming the bonds between its phosphate groups. This characteristic of ATP makes it exceptionally useful as a basic energy source for all cells.

17. Quick Check  What is energy?  The ability to do work  Can energy be created?  No  Can energy be destroyed?  No List some forms of energy. Thermal/heat, mechanical, chemical, light Analyze why living things need energy. To grow, to move, to reproduce, to break down food, etc… How do humans obtain energy? By eating and digesting food

18. Journal  Explain how ADP and ATP are like a battery in the cell. Which one is partially charged and which one is fully charged?

19. JOURNAL  Using vocabulary from 8-1, discuss the metabolic pathway that includes photosynthesis and cellular respiration.

20. JOURNAL  Explain how the ultimate source of energy for heterotrophs is the sun even though they cannot make their own food.

21. energy thermodynamics metabolism Photosynthesis cellular respiration adenosine triphosphate (ATP) Cellular Energy Vocabulary Section 1