Lecture Notes: Cellular Respiration and Chemical Reactions

Introduction

• Date: April 7
• Cancellations:
  • Homework 6a and 6b are canceled.
• Upcoming Assignment:
  • Homework 7: Start early, do not wait until the last minute.
• Exam Schedule:
  • Two more meetings followed by an exam.

Key Topics Discussed

Importance of Preparation

• Videos are crucial for understanding abstract concepts.
• Topics like cellular respiration require detailed study as they are unfamiliar to most.

Chemical Reactions in Biology

• Catabolic Reactions: Break down molecules to release energy.
• Anabolic Reactions: Build up molecules, e.g., making fat or muscle protein.
• Exergonic Reactions: Release energy.
• Endergonic Reactions: Require energy input.

Redox Reactions

• Mnemonic: OIL RIG
  • Oxidation Is Losing (Electrons/Hydrogens)
  • Reduction Is Gaining (Electrons/Hydrogens)
• Example Reactions:
  • Malic acid to oxaloacetic acid involves oxidation (loss of hydrogens).
  • Pyruvic acid to lactic acid involves reduction (gain of hydrogens).

Analysis of Coupled Reactions

• Counting hydrogens helps determine reduction or oxidation status.
• Larger molecules have more potential energy.
• ATP and ADP:
  • ATP to ADP alone is exergonic (energy releasing).

Practice Questions

• Emphasis on practice for understanding complex reactions.
• Reactions can have multiple perspectives, e.g., energy focus vs. electron/hydrogen focus.

Cellular Respiration Overview

• Stages: Glycolysis, Intermediate Step, Citric Acid Cycle, Oxidative Phosphorylation.
• Glycolysis: Breaks glucose to extract electrons.
• Intermediate Step: Oxidizes pyruvate, prepares it for the mitochondria.
  • Reactants: Pyruvate, NAD+, Coenzyme A.
  • Products: Acetyl CoA, CO2, NADH.

Polls and Feedback

• Preferences for online vs. on-campus classes were discussed.
• Reasons include focus, accountability, convenience, cost of travel/gas.

Conclusion

• Practice is key for mastering concepts.
• Email instructor for answer keys or additional resources if needed.

Next Steps

• Review videos on glycolysis and other stages.
• Complete practice questions by next class.
• Email instructor for answer keys to practice problems.