Question

Because of the mitochondrial location of pyruvate carboxylase, and the inability of oxaloacetate (OAA) to cross the mitochondrial membrane, we need to transport it as either ________ or ________.

Answer 1

Oxaloacetate (OAA), which cannot cross the mitochondrial membrane, is transported as either malate or aspartate after conversion, linking metabolic pathways such as the citric acid cycle and gluconeogenesis.

Step-by-step explanation:

Because of the mitochondrial location of pyruvate carboxylase, and the inability of oxaloacetate (OAA) to cross the mitochondrial membrane, we need to transport it as either malate or aspartate.

The mitochondrial enzyme pyruvate carboxylase converts pyruvate into oxaloacetate (OAA). However, OAA cannot directly cross the mitochondrial membrane. To facilitate its transport into the cytosol where it can be used for gluconeogenesis or other pathways, it is converted into malate or aspartate, which can cross the membrane. In the cytosol, malate can be reconverted back into OAA. This transportation is essential for connecting various metabolic pathways such as the citric acid cycle and gluconeogenesis, contributing to the metabolic flexibility of the cell.