Oxaloacetate Metabolism

The video explores gluconeogenesis, focusing on the transport of oxaloacetate from the mitochondria to the cytosol. It explains the conversion of pyruvate to oxaloacetate, the role of malate as a shuttle, and the formation of phosphoenolpyruvate. Two pathways are discussed: one involving cytosolic PEP carboxykinase and another using mitochondrial PEP carboxykinase. The video concludes with a brief mention of glycolysis and gluconeogenesis regulation by phosphofructokinase 2.

What is the main challenge in transporting oxaloacetate from the mitochondria to the cytosol?

• Oxaloacetate is too large to pass through the mitochondrial membrane.

• The cytosol lacks the enzymes to process oxaloacetate.

• There are no oxaloacetate transporters in the mitochondrial membrane.

• Oxaloacetate is not stable outside the mitochondria.

Which enzyme is responsible for converting oxaloacetate to malate in the mitochondria?

• Pyruvate carboxylase

• Malate dehydrogenase

• PEP carboxykinase

• Lactate dehydrogenase

What is the role of malate in the transport of oxaloacetate?

• Malate acts as a carrier to transport oxaloacetate out of the mitochondria.

• Malate inhibits the transport of oxaloacetate.

• Malate is converted to pyruvate in the cytosol.

• Malate is a byproduct that needs to be removed.

How is phosphoenolpyruvate (PEP) generated in the mitochondria?

• By the action of cytosolic PEP carboxykinase

• Through the conversion of malate

• By mitochondrial PEP carboxykinase

• By direct transport of oxaloacetate

What is the significance of phosphoenolpyruvate transporters in the mitochondrial membrane?

• They allow PEP to be converted back to oxaloacetate.

• They facilitate the conversion of PEP to pyruvate.

• They enable PEP to exit the mitochondria and enter the cytosol.

• They prevent the accumulation of PEP in the cytosol.

What is the next topic to be covered after the discussion on oxaloacetate transport?

• The role of pyruvate in gluconeogenesis

• The regulation of glycolysis and gluconeogenesis by phosphofructokinase 2

• The conversion of glucose to glycogen

• The transport of ATP across the mitochondrial membrane

Why is phosphofructokinase 2 important in the regulation of glycolysis and gluconeogenesis?

• It is involved in the synthesis of ATP.

• It transports oxaloacetate across the mitochondrial membrane.

• It is a regulatory enzyme that affects both processes.

• It catalyzes the conversion of glucose to glycogen.