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.