Cell Energetics Concept Review

1. Cell Energetics Concept Review

2. Energy: Big Idea in Science • Energy flows in one direction, energy never cycles back to its source

3. What is energy? • Energy is the capacity to do work • Work is the transfer of energy • Using the definition, explain how ATP is a form of energy.

4. There are different forms of energy: • Light • Chemical • Heat • Potential Energy: Stored energy • Kinetic Energy: Energy of motion

5. The 1st Law of Thermodynamics • The total amount of energy in the universe is constant. Energy can’t be created or destroyed, it can only change forms. • EVERY energy transfer results in some energy being lost to the environment as heat. Energy transfers are NEVER 100% efficient.

6. Example in Biology

7. The 2nd Law of Thermodynamics (The Law of Entropy) • In the absence of energy inputs, an organized system becomes more disorganized over time. • Organized Disorganized • Concentrated Diffuse • Complex Simple

8. Example in Biology

9. Endergonic Reactions Net increase of usable energy (energy in), transforming CO2 and H2O to glucose. A + B + energy AB Exergonic Reactions Net decrease of usable energy (energy out), transforming glucose to CO2 and H2O. AB Energy + A + B Energy Reactions

10. Metabolic Pathways

11. Metabolic pathway where small molecules are used to build larger molecules of higher bond energy. Example: The synthesis of carbohydrates in photosynthesis. Biosynthetic Pathway (Anabolic)

12. Degradative Pathway (Catabolic): • Exergonic pathways that breaks down large molecules to smaller ones. • Example: Cellular respiration

13. Coupled Reaction • The use of an exergonic reaction to drive an endergonic reaction. ATP is responsible for mediating most energy coupling in cells. • Example: Energy from ATP is transferred to glucose to initiate glycolysis

14. The Structure of Adenosine Triphosphate (ATP) • ATP (adenosine triphosphate) is the cell’s energy shuttle • ATP is composed of ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups

15. How is Energy Released from ATP? • Energy is released when the terminal phosphate bond is broken during hydrolysis

16. ATP Energy Transfer • Enzymes couple the energy of ATP hydrolysis directly to endergonic reactions by transferring a phosphate group from ATP to another molecule. • The recipient of the phosphate group has been “phosphorylated”.

17. Substrate Level Phosphorylation • Enzymes directly transfer a phosphate group from a substrate of a reaction to ADP. • Example: The formation of ATP from PGAL during glycolysis.

18. Electron Transfer or Oxidative Phosphorylation • The production of ATP using energy derived from the redox reactions of and electron transport chain. • The combined processes of chemiosmosis and electron transport

19. Chemiosmosis • An energy coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane through ATP Synthase to drive cellular work such as the synthesis of ATP. • What drives ATP synthase to form ATP

20. Enzyme Induced Fit Model • There are weak interactions between an enzyme and its substrate upon binding which induce change in the enzyme’s shape.