Biochemistry 153A: Week 10 Discussion
The TCA Cycle, ETS and ATP



I. TCA cycle
PDH complex. The bridge step.
Overall catabolism and anabolism of TCA
For each of the 8 steps: Spontaneous or Near-Equilibrium/Concentration-Dependent
Regulation by + or - effectors
Notable points

p. 83, # 8
When there are fluctuations in the steady-state concentrations of important compounds in a living cell, the regulatory mechanisms of the cell respond in order to return the cell to normal steady-state conditions.
Predict the relative levels of activity of the following mammalian enzymes under the given conditions.
The following lines became a total mess when I transferred to HTML, so refer to your Problems Book for best results.
Enzyme Cellular conditions Relative activity
High Med Low
Hexokinase average glc, high G6P, high citrate ____ ____ ____
Glucokinase high glc, high ATP, high citrate ____ ____ ____
Glucokinase average glc, high ATP, high citrate ____ ____ ____
Phosphofructokinase average glc, high ATP, average citrate ____ ____ ____
Isocitrate dehydrogenasehigh glc, average ATP, high NADH, high citrate ____ ________
Pyruvate carboxylase high glc, high ATP, high NADH, high AcCoA ____ ____ ___
Phosphofructokinase high glc, average ATP, high NADH ____ ____ ____

II. ETS: Electron Transport System and ATP synthase
A proton gradient is established across the inner mitochondrial membrane that generates a proton-motive force that drives ATP synthesis
If ATP is considered the energy "currency" of a cell, the denomination of an ATP molecule is an amount that is readily negotiable.

The big picture:


III. Return Quizzes and distribute Evaluations

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