Tocopherols and Antioxidant Mechanism Quiz

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What is the main biochemical role of vitamin K?

Cofactor for carboxylation of glutamic acid residues in proteins involved in blood coagulation (correct)

Regulation of senescence and malignant transformations

Activation of tocopherols as antioxidants

Prevention of atherosclerosis

Which source is the most rich in tocopherols?

Liver

Seeds

Eggs

Vegetable oils (correct)

How do tocopheroxyl radicals get regenerated under antioxidant action?

They react with oxygen

Other molecules with antioxidant capacity can regenerate them (correct)

They combine with glutamic acid residues

They are eliminated from the body

What is the recommended daily allowance (RDA) for alpha-tocopherol in adults?

15 mg/day Signup and view all the answers

Which of the following is NOT a form of vitamin K?

Menadione (vitamin K3) Signup and view all the answers

What happens to the requirement for tocopherols as the intake of polyunsaturated fatty acids increases?

It increases Signup and view all the answers

What is the main biochemical role of vitamin E in the body?

Acts as an antioxidant in lipids Signup and view all the answers

Which of the following is a tocopherol compound of vitamin E?

α-tocopherol Signup and view all the answers

What can happen if there is a deficiency in vitamin E?

Oxidative damage to cell membranes Signup and view all the answers

How is vitamin D different from vitamin E in terms of storage and metabolism?

Vitamin E can be stored in the body, while vitamin D cannot be stored. Signup and view all the answers

Which type of compounds are tocotrienols in vitamin E?

Compounds with an isoprene chain attached Signup and view all the answers

What harmful effect can excess vitamin D intake have on the body?

Deposition of calcium salts in soft tissue Signup and view all the answers

What is the enzyme present in the human intestine that can cleave β-carotene into two molecules of retinal?

Carotenase Signup and view all the answers

What is the efficiency of the conversion of β-carotene into retinal compared to retinol?

1/12 Signup and view all the answers

In which part of the molecule does the cleavage of β-carotene to retinal occur?

Middle Signup and view all the answers

What is the active form derived from the oxidation of retinol?

Retinal Signup and view all the answers

Which vitamin A form is essential in vision and exists as 11-cis retinal bound to protein opsin in rod cells of the retina?