Energy Transformations in Cells

Importance of Energy in Cells

• Activities of a cell require energy to function (movement, metabolism, reproduction, transport, maintaining internal environment).
• Energy is defined as the ability to do work.

Sources of Energy

• Heterotrophs: Obtain energy from consuming food; rely on other organisms.
• Autotrophs: Obtain energy from sunlight through photosynthesis; self-reliant.

Photosynthesis

• Converts light energy into chemical energy (glucose).
• Chemical equation: 6 CO2 + 6 H2O + light -> C6H12O6 + 6 O2.
• Photosynthesis uses energy to create glucose, not energy itself.

Cellular Respiration

Aerobic Respiration

• Breakdown of glucose in the presence of oxygen to produce energy.
• Reaction: C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O + energy.
• Produces 30-32 ATP molecules (energy units).

Anaerobic Processes

Fermentation

• Occurs without oxygen; less efficient (produces 2 ATP).
• Different types:
  • Yeast/Plant/Bacteria Fermentation: Produces ethanol and CO2.
  • Animal Fermentation: Produces lactic acid.

ATP: The Energy Currency

• ATP (Adenosine triphosphate) acts as a cell's energy currency.
• Stores energy in a high-energy chemical bond (third phosphate group).

ATP and Energy Transfer

• ATP Hydrolysis: Breaks down ATP to ADP (Adenosine diphosphate) and inorganic phosphate, releasing energy.
• ATP Synthesis: Converts ADP back to ATP using energy from respiration, recharging the "battery".

Significance of ATP

• Powers all cell activities, providing the necessary activation energy for chemical reactions.
• Central to cell's energy management, crucial for sustaining life processes.