Chapter 15 Glycolysis

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Overview:

We will focus on glycolysis and the citric acid cycle with respect to:

intermediates and enzymes

regulation

energy "currency" (e.g., ATP)

role of electron carriers

Glycolysis: the conversion of glucose to pyruvate for which the overall equation is as follows: Glc + 2ADP + 2Pi + 2NAD+ gives 2pyruvate + 2ATP + 2NADH + 2H+ + 2H2O

We will examine the nature of each step (10 of them) and you will be expected to know the first four items in the following list for each step:

starting material and product (structures and names)

enzyme

regulation, where appropriate

production and consumption of energy-rich molecules

and electron acceptors/donors agents

details, where appropriate, of enzyme mechanism

Step 1:

metabolically irreversible

regulation: Glc-6P allosterically inhibits

Step 2:

near equilibrium reaction

Step 3:

metabolically irreversible

allosteric regulation

Steps 4 and 5: (note the two ways in which fructose 1,6-diphosphate is represented)

Both are near equilibrium reactions

Step 6:

only oxidation reaction in glycolysis

near equilibrium reaction

mechanism: thioester formation

begins "energy recovery phase" of glycolysis

 

Step 7:

near equilibrium reaction

note: each glucose leads to two 1,3-BPGs; therefore, there are 2 ATPs produced for every glucose.

Step 8:

near equilibrium reaction

Step 9:

near equilibrium reaction

 

Step 10:

metabolically irreversible

regulation

summary of molecular transformations

summary of regulated steps

summary of metabolically irreversible versus near-equilibrium reactions