Understanding Energy Transformations in Biology

Aug 14, 2024

Lecture on Energy Transformation in Biological Systems

Introduction

  • The heart beats 3-5 times in three seconds, requiring constant energy.
  • Energy for biological work originates from the sun.
  • Energy transformation is necessary for body usage.

Energy Source and Transformation

From Sun to Usable Energy

  • Energy originally comes from the sun.
  • Plants convert energy from sunlight into glucose via photosynthesis.
  • Animals and humans consume glucose, converting it into ATP through cellular respiration.

Photosynthesis

  • Occurs in the chloroplasts of plant cells.
  • Light Reaction:
    • Energy from light splits H2O, releasing a hydrogen ion.
    • Hydrogen is captured by NADP to form NADPH.
    • ATP is formed.
    • NADPH serves as a high-energy electron carrier.
  • Calvin Cycle:
    • Starts with CO2, NADPH, and ATP.
    • Series of reactions lead to glucose production.
    • Converts sunlight energy into glucose bonds.

Cellular Respiration

  • Process Overview:
    • Begins with breaking down glucose into pyruvate, releasing some ATP.
    • Pyruvate is converted to Acetyl CoA.
  • TCA Cycle / Krebs Cycle / Citric Acid Cycle:
    • Acetyl CoA enters the cycle.
    • Produces CO2, NADH, and FADH2, which are electron carriers.
  • Electron Transport Chain:
    • Electrons from NADH and FADH2 are used to form H2O.
    • Drives ATP production through an enzymatic pump.

Comparison of Photosynthesis and Cellular Respiration

  • Photosynthesis and cellular respiration are reverse processes.
  • Photosynthesis Equation:
    • 6 CO2 + 6 H2O → C6H12O6 + 6 O2
  • Cellular Respiration Equation:
    • C6H12O6 + 6 O2 → 6 CO2 + 6 H2O
  • Energy is a reactant in photosynthesis (stored in glucose bonds) and a product in cellular respiration (released from glucose bonds).

Energy Changes in Reactions

  • Photosynthesis:
    • Converts low to high free energy (adds energy from sunlight).
  • Cellular Respiration:
    • Converts high to low free energy (releases energy to produce ATP).
  • Energy release enables biological work, such as heart pumping.

These transformations are crucial for understanding how energy is harnessed and utilized by living organisms to maintain life processes.