Vitamin C: Metabolism and Function

The video discusses ascorbate, commonly known as vitamin C, highlighting its role as an antioxidant. It explains the biosynthesis of ascorbate in animals and plants, noting that humans cannot synthesize it and must obtain it through diet. The video covers the properties of vitamin C, its water solubility, and its mechanism as a radical scavenger. It details the enzymes involved in ascorbate metabolism, such as ascorbate peroxidase, and describes the electron transport chain and disproportionation reactions. The video also explains how ascorbate is taken up by cells and the role of the peroxisome in ascorbate metabolism.

Why can't humans synthesize ascorbate?

• Their bodies convert it into another compound.

• They do not consume enough vitamin C.

• The gene for the final enzyme is inactive.

• They lack the entire biosynthetic pathway.

What makes vitamin C different from vitamins A, D, E, and K?

• It is not an antioxidant.

• It is water-soluble.

• It is synthesized by humans.

• It is fat-soluble.

How does ascorbate neutralize free radicals?

• By binding to proteins.

• By absorbing light.

• By donating electrons.

• By donating protons.

What is the role of ascorbate peroxidase in ascorbate metabolism?

• It converts ascorbate to vitamin A.

• It removes electrons from ascorbate.

• It synthesizes ascorbate from glucose.

• It adds electrons to ascorbate.

Which enzyme converts dehydroascorbate back to ascorbate?

• Catalase

• Glutathione reductase

• Dehydroascorbate dehydrogenase

• Ascorbate peroxidase

What is the primary free radical scavenger in human blood?

• Hydrogen peroxide

• Glutathione

• Uric acid

• Ascorbate

Where do many ascorbate conversions occur in the cell?

• Cytoplasm

• Nucleus

• Peroxisome

• Mitochondria