Catabolic Pathways and Glycolysis• The ability to do that work depends on catabolic process that harvest

the potential energy found in organic molecules. The 2 catabolic processes that occur in organisms are fermentation (breakdown without O2)and cellular respiration (breakdown with O2).

Chemical Energy and Food• Chemical energy can be found contained within the foods that we eat.

Calories are the basic measurement of the energy contained in foods.– 1cal = 4.184J– 1000cal = 1kcal = 1Cal (standard for our food labeling)– The average diet is built around 2000Cal

• Not all Calories are created equally– 1g carbohydrate = 4Cal– 1g protein = 4Cal– 1g fat = 9Cal

• RDA recommendations– carbohydrate = 55%– protein = 15%– fat = 30%

Cellular Respiration • primary catabolic pathway used in organisms to produce energy

(ATP) – although fats & proteins can be broken down, glucose is the primary

fuel used – C6H12O6 + 6O2 g 6CO2 + H2O + Energy (ATP & Heat)

Stages of Cellular Respiration• Glycolysis • Citric Acid Cycle • Oxidative Phosphorylation

Glycolysis• Catabolic process that degrades glucose into 2

Pyruvate molecules + 2 H2O molecules – occurs in the cytosol – requires the input of 2 ATP molecules and produces 4

ATPs (net of 2) – 2 NAD+ are reduced to 2 NADH + 2 H+ (net gain of 4e-)

• Pyruvate is then transported into the mitochondria to begin the Citric Acid Cycle

• Reaction does not require oxygen (anaerobic process) – No CO2 is produced! – All C atoms are present in the final products of the

reactions • Simplified equation

– Glucose + 2ATP + 2NAD+ g 2Pyruvate + 4ATP + 2NADH + 2H+

– The left side is called the Energy Investment phase – The right side is called the Energy Payoff phase