The Biotin Cycle | Mammalian Biotin (Vitamin B7) Metabolism & Processing

The video tutorial explains the importance of biotin (vitamin B7) as an essential nutrient that must be ingested directly, as it cannot be synthesized by humans. It covers the biotin cycle, its chemical structure, and its role as a cofactor in enzyme activation, particularly in carboxylation reactions. The process of biotinylation, where biotin is attached to enzymes, is detailed, along with examples of enzymes that require biotin. The video also discusses how biotin is digested and recycled in the body, emphasizing the role of enzymes like biotinidase in this process.

What is the primary role of biotin in the human body?

• To act as a coenzyme in carboxylation reactions

• To transport oxygen in the blood

• To store energy

• To synthesize proteins

How is biotin typically ingested in the diet?

• As a free molecule

• Bound to proteins

• In the form of carbohydrates

• As a lipid

What is the function of holo carboxylate synthetase?

• To break down proteins

• To synthesize ATP

• To attach biotin to apo carboxylases

• To transport biotin in the bloodstream

Which molecule is required for the carboxylation reaction catalyzed by holo carboxylases?

• Bicarbonate

• Oxygen

• Glucose

• Nitrogen

Which enzyme is involved in the catabolism of amino acids and requires biotin?

• Amylase

• Lactase

• 3-methylcrotonyl-CoA carboxylase

• Pyruvate carboxylase

What is the role of biotinidase in the biotin cycle?

• To synthesize biotin

• To attach biotin to proteins

• To hydrolyze biocytin and release free biotin

• To transport biotin in the blood

What happens to biotin when it is ingested as part of a protein?

• It is immediately absorbed in the bloodstream

• It is released as free biotin after proteolysis and biotinidase action

• It is broken down into amino acids

• It is stored in the liver