Unit 2: Metabolic Processes Glycolysis and Pyruvate Oxidation SBI4U – Ms. Richardson

Glycolysis Occurs in the cytoplasm of plant and animal cells Process is anaerobic, oxygen is not required Purpose is to split 6-carbon glucose into 2 molecules of 3-carbon pyruvate

Main Reactants: Glucose ATP Glycolysis Main Reactants: Glucose ATP

Main Products: Pyruvate ATP NADH Glycolysis Main Products: Pyruvate ATP NADH

Glycolysis: Overview 4 ATP produced, 2 ATP used Net 2 ATP produced 2 NADH produced 2 pyruvate produced

Glycolysis: Details Glucose is converted through a series of reactions to fructose-1,6-bisphosphate bisphosphate – 2 phosphate groups have been added Phosphate groups are obtained from ATP, so 2 ATP have been used Fructose-1,6-bisphosphate is converted to 2 glyceraldehyde-3-phosphate (G3P) molecules Each G3P molecule accepts an H atom (carrying 1 proton and 2 electrons) and electrons are donated to NAD+ NAD+ is reduced to NADH Each G3P is converted to pyruvate The reaction requires 2 ATP and produces 4 ATP (net 2 ATP produced)

Glycolysis: Summary

Glycolysis: Summary Overall chemical equation for glycolysis: Glucose + 2ADP + 2Pi + 2NAD+  2 pyruvate + 2ATP + 2H2O + 2NADH

Glycolysis Glycolysis only transfers 2.1% of free energy available in 1 mol of glucose to ATP Some energy is released as heat, most is trapped in pyruvate and NADH molecules

Pyruvate Oxidation Intermediate step between glycolysis and Krebs cycle The 2 pyruvate molecules transported from cytoplasm to the matrix Aerobic, requires oxygen

2 acetyl-CoA + 2NADH + 2H+ + 2CO2 Pyruvate Oxidation 3 changes occur: 2CO2 removed (1 from each pyruvate) Pyruvate oxidized to acetic acid, NAD+ is reduced to NADH Coenzyme A (CoA) attaches to form acetyl-CoA 2 pyruvate + 2NAD+ + 2CoA  2 acetyl-CoA + 2NADH + 2H+ + 2CO2