Cellular energetics flashcards

Cellular energetics covers how cells capture, store, and use energy to power life processes. Students must understand photosynthesis, in which light energy is converted to chemical energy stored in glucose, and cellular respiration, in which that glucose is broken down to produce ATP. Key concepts include the role of ATP as the cell's primary energy currency, the structure and function of enzymes and how they lower activation energy, the light-dependent and light-independent reactions of photosynthesis, and the stages of cellular respiration including glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation. Students should also understand how the electron transport chain creates a proton gradient used to drive ATP synthesis, and how fermentation allows ATP production without oxygen.

1. Card 1

   What is the primary role of ATP in the cell?

   ATP (adenosine triphosphate) serves as the cell's main energy currency, releasing usable energy when its terminal phosphate bond is hydrolyzed to form ADP.

2. Card 2

   How do enzymes affect activation energy in a reaction?

   Enzymes are biological catalysts that lower activation energy by stabilizing the transition state, speeding up reactions without being consumed.

3. Card 3

   Where do the light-dependent reactions of photosynthesis occur?

   The light-dependent reactions occur in the thylakoid membranes, where chlorophyll absorbs light to split water, releasing O2 and producing ATP and NADPH.

4. Card 4

   What is the overall purpose of the Calvin cycle?

   The Calvin cycle uses ATP and NADPH from the light reactions to fix CO2 into G3P (glyceraldehyde-3-phosphate), which can be used to build glucose.

5. Card 5

   What happens during glycolysis?

   Glycolysis occurs in the cytoplasm and splits one glucose into two pyruvate molecules, producing a net gain of 2 ATP and 2 NADH.

6. Card 6

   What is the role of the electron transport chain in cellular respiration?

   The electron transport chain passes high-energy electrons through membrane proteins, pumping H+ ions to create a gradient that drives ATP synthase to produce ATP.

7. Card 7

   What is chemiosmosis?

   Chemiosmosis is the movement of H+ ions down their concentration gradient through ATP synthase, releasing energy used to phosphorylate ADP into ATP.

8. Card 8

   What is the net ATP yield from one glucose molecule in aerobic respiration?

   Aerobic cellular respiration yields approximately 30 to 32 ATP per glucose, most of which is produced by oxidative phosphorylation in the mitochondria.

9. Card 9

   How does fermentation allow continued ATP production without oxygen?

   Fermentation regenerates NAD+ by transferring electrons to pyruvate or acetaldehyde, allowing glycolysis to continue producing small amounts of ATP anaerobically.

10. Card 10

    What is the function of NADH and FADH2 in cellular respiration?

    NADH and FADH2 are electron carriers that deliver high-energy electrons to the electron transport chain, where their energy is used to generate ATP.

11. Card 11

    What is the significance of the proton gradient across the inner mitochondrial membrane?

    The proton gradient stores potential energy; as H+ flows back through ATP synthase, that energy drives ATP synthesis in a process called chemiosmosis.

12. Card 12

    How does an inhibitor that blocks ATP synthase affect the proton gradient?

    Blocking ATP synthase causes the proton gradient to build up and not be discharged, halting ATP production even though the electron transport chain may still run briefly.

• Many students confuse the location of glycolysis (cytoplasm) with the citric acid cycle and electron transport chain (mitochondria), incorrectly placing all stages of respiration inside the mitochondrion.
• Students often assume that fermentation produces large amounts of ATP, when in reality it produces no additional ATP beyond what glycolysis already yields; its purpose is simply to regenerate NAD+ so glycolysis can continue.
• A common error is treating the approximate ATP yield of 30 to 32 per glucose as an exact, fixed number rather than an estimate that varies based on membrane efficiency and cellular conditions.

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