Bchadvanced
Arrange these events in the gluconeogenic route from pyruvate to phosphoenolpyruvate.
Answer
Pyruvate enters the mitochondrion., Pyruvate carboxylase forms oxaloacetate., Oxaloacetate is reduced to malate for transport out of the mitochondrion., Cytoplasmic malate is converted back to oxaloacetate., Phosphoenolpyruvate carboxykinase forms phosphoenolpyruvate.
Explanation
### The order
1. Pyruvate must reach the mitochondrion, where pyruvate carboxylase is located.
2. Carboxylation forms oxaloacetate.
3. Oxaloacetate cannot cross the inner mitochondrial membrane, so it is reduced to transportable malate.
4. In the cytoplasm, malate is oxidized back to oxaloacetate.
5. Cytoplasmic phosphoenolpyruvate carboxykinase forms phosphoenolpyruvate.
### Terms
- **Oxaloacetate**: A four-carbon metabolic intermediate.
- **Malate**: The reduced form used to transport oxaloacetate carbon across the membrane.
### Remember
Malate is the transport form because oxaloacetate cannot cross the inner mitochondrial membrane.
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