Download Catabolic Pathways and Glycolysis

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
• 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
Glycolysis