Lecture on ATP and Aerobic Cellular Respiration

Introduction

• Discussion on whether the speaker is a morning person.
• Cells cannot afford to be sluggish, constantly performing processes like active transport.
• Energy currency for cells is ATP (Adenosine Triphosphate).
  • ATP: A nucleic acid with three phosphates.

ATP Production

• All cells (prokaryote and eukaryote) must produce ATP.
• Production methods vary based on cell type.
• Focus of the lecture: Aerobic Cellular Respiration in Eukaryotic Cells.
• Organelles involved: Nucleus and mitochondria.

Aerobic Cellular Respiration

• Goal: To make ATP.
• Similarities to photosynthesis, but not simply opposites.
• Example of germinating beans using stored glucose for ATP before photosynthesis.
  • Plants can perform both photosynthesis and cellular respiration.
  • Non-photosynthetic organisms need food source for glucose.

Steps of Aerobic Cellular Respiration

Step #1: Glycolysis

• Takes place in the cytoplasm, anaerobic process.
• Glucose is converted into pyruvate.
• Net yield: 2 pyruvate, 2 ATP, 2 NADH.
• NADH: Coenzyme for electron transfer.

Intermediate Step

• Pyruvate transported to mitochondria, oxidized to produce 2 acetyl CoA.
• Releases carbon dioxide and produces 2 NADH.

Step #2: The Krebs Cycle (Citric Acid Cycle)

• Occurs in the mitochondrial matrix, considered aerobic.
• Acetyl CoA enters the cycle.
• Releases carbon dioxide, produces 2 ATP, 6 NADH, and 2 FADH2.

Step #3: Electron Transport Chain and Chemiosmosis

• Takes place in the inner mitochondrial membrane, aerobic step.
• Electrons from NADH and FADH2 transferred to protein complexes, creating a proton gradient.
• Protons travel through ATP synthase, producing ATP.
• Oxygen acts as the final electron acceptor, forming water.
• Produces 26-34 ATP per glucose molecule in this step alone.

Total ATP Production

• Combined ATP from all steps ranges between 30-38 ATP per glucose molecule.
• Emphasis on understanding variability in ATP yield rather than memorizing a fixed number.

Alternative ATP Production Method

• Fermentation as an alternative in the absence of oxygen.
• Less efficient than aerobic respiration.

Importance of ATP

• Essential for cell survival.
• Cyanide can block ATP production by disrupting the electron transport chain.
• Mitochondrial diseases highlight the importance of understanding ATP production.

Conclusion

• Encouragement to stay curious and continue exploring cellular processes.