Malate-Aspartate Shuttle

The video explains the malate aspartate shuttle, a crucial mechanism for transporting NADH from glycolysis into the mitochondria for ATP production. It details the impermeability of the mitochondrial membrane to NADH and the role of antiporters in the shuttle process. The video covers the enzymatic reactions involved, including the conversion of oxaloacetate to malate and back, and the role of concentration gradients. It also discusses the cycle of aspartate and glutamate and the shuttle's application in gluconeogenesis.

Why is the malate aspartate shuttle necessary for NADH transport into mitochondria?

• The mitochondrial membrane is impermeable to NADH.

• NADH is too large to pass through the membrane.

• NADH is unstable outside the cytosol.

• NADH is converted to ATP outside the mitochondria.

What is the role of antiporters in the malate aspartate shuttle?

• They convert NADH to ATP.

• They stabilize the mitochondrial membrane.

• They transport NADH directly.

• They facilitate the exchange of molecules across the membrane.

Which cells primarily utilize the malate aspartate shuttle?

• Skin and bone cells

• Red blood cells and platelets

• Cardiac muscle and liver cells

• Neurons and muscle cells

What role does oxaloacetate play in the malate aspartate shuttle?

• It stabilizes the mitochondrial membrane.

• It directly enters the mitochondria.

• It is converted into ATP.

• It acts as a carrier for energy within NADH.

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

• Pyruvate carboxylase

• Aspartate aminotransferase

• Mitochondrial malate dehydrogenase

• Cytosolic malate dehydrogenase

What is the function of glutamate in the malate aspartate shuttle?

• It acts as a carrier for NADH.

• It donates an amino group to oxaloacetate.

• It stabilizes the mitochondrial membrane.

• It is converted into ATP.

How is aspartate transported out of the mitochondria?

• Through a malate transporter

• Via the glutamate aspartate antiporter

• Directly through the mitochondrial membrane

• By converting into oxaloacetate first

In gluconeogenesis, what is the initial substrate that enters the mitochondria?

• Oxaloacetate

• Aspartate

• Malate

• Pyruvate

What enzyme converts oxaloacetate to phosphoenolpyruvate in gluconeogenesis?

• PEP carboxykinase

• Aspartate aminotransferase

• Malate dehydrogenase

• Pyruvate carboxylase

Why does the direction of the malate aspartate shuttle change during gluconeogenesis?

• To increase oxaloacetate concentration

• Because of higher NADH levels in the mitochondria

• Due to increased ATP demand

• To stabilize the mitochondrial membrane