Cellular Respiration

Activation energy

The energy required for a chemical reaction to occur.

Enzymes

Biological catalysts that lower the activation energy of reactions, allowing them to occur at normal body temperature.

Cellular respiration

The process by which organic molecules are broken down to release energy for the cell’s activities.

Summary equation of cellular respiration

glucose + oxygen → water + carbon dioxide, or C6H12O6 + 6O2 → 6H2O + 6CO2.

Adenosine triphosphate (ATP)

A recyclable energy storage molecule that consists of an adenosine molecule joined to three phosphate molecules.

Energy shuttle

ATP acts as an energy shuttle between reactions, transferring energy where it is needed in the cell.

Glycolysis

The first step in cellular respiration that occurs in the cytoplasm and does not require oxygen; it breaks down glucose into two molecules of pyruvic acid.

Anaerobic respiration

Occurs after glycolysis if insufficient oxygen is present, converting pyruvic acid into lactic acid and allowing glycolysis to continue.

Aerobic respiration

Occurs in the mitochondria after glycolysis when oxygen is present, fully breaking down pyruvic acid into carbon dioxide and water.

Kreb’s cycle

Also known as the citric acid cycle, it produces 2 ATP from the aerobic breakdown of pyruvic acid.

Electron transport chain

The final step of aerobic respiration that can produce up to 34 ATP.

Energy use by the cell

Energy produced by cellular respiration is used for processes like movement of organelles, cell division, growth, and synthesis of complex molecules.

Energy capture efficiency

40% of the energy from respiration is actually captured, while 60% is lost as heat.

Oxygen debt

The oxygen required for the conversion of lactic acid back to glucose in the liver after exercise.