Vitamins are organic nutrients that are required for the proper functioning of a no. of biomolecules. These vitamins are not synthesized in the body that’s why they must be supplied through the diet. Classification of vitamins Vitamins are divided in two groups based on their solubility:

• • Water soluble vitamins
  • Fat soluble vitamins

Water soluble vitamins include vitamin B complex, Vitamin C and Biotin.

• Thiamine (VitaminB1):- Thiamine consists of pyrimidine ring attached to a thiazole ring. it helps the body to convert food into energy. It also aids the function of heart and brain.
• Riboflavin (Vitamin B2):- It is a yellow compound consisting of an isoalloxazine ring with rabitol side chain. It works with other vitamins of B complex for healthy growth and tissue repair. It also helps to release energy from carbohydrates.
• Niacin (Vitamin B3):- It is a simple derivative of pyrimidine. It helps to release energy from carbohydrates. It also plays an important role in DNA repair and other cellular responses to DNA damage.
• Pantothenic acid (Vitamin B5):- It is formed from the combination of pantoic acid and beta-alanine. It is a component of acetyl-CoA and acyl carrier protein (ACP).
• Pyridoxine (Vitamin B6):- It is formed from the mixture of 3 pyridine derivatives which are: pyridoxine, pyridoxal and pyridoxamine. It is important in forming RBC, breakdown of proteins, synthesis of antibodies etc.
• Folic acid (Vitamin B9):- Consist of 3 components: pteridine ring, p-amino benzoic acid and L-glutamic acid. It aids the production of RBCs and synthesis of DNA.
• Cynocobalamin (VitaminB12):- It is important for the metabolism, formation of RBCs, and maintenance of CNS.
• Ascorbic acid (Vitamin C):– It is a six carbon sugar derivative. It works as reducing agent. It is also required in bone as well as for wound healing process. It prevents atherosclerosis and coronary artery diseases.
• Biotin (Vitamin H):- It is an imidazole derivative. Biotin is a co-enzyme of carboxylase reactions.

Fat soluble vitamins include

• Vitamin A:- Vitamin A contains a 6-membered ring to which 11-carbon side chain is attached. Vitamin A is an alcohol (retinol) but it cannot be converted into aldehyde (retinal) or an acid (retinoic acid).

It maintains health of specialized tissue like retina, also promotes the development of teeth, soft and skeletal tissue.

• Vitamin D (Cholecalciferol):- It regulates blood-calcium and blood-phosphorous, regulates calcification of bone. Deficiency of vitamin D leads to rickets.
• Tocopherol (Vitamin E):- It consist of eight naturally occurring tocopherols. It protects the cell membrane and tissue. It promotes healthy functions of circulatory systems.
• Vitamin K:- It plays an important role in blood coagulation. It is required for carboxylation of glutamic acid. It acts as a calcium-binding protein in bones.

Sources of vitamins

Multiple choice questions (MCQs)

1. What are vitamins?

A. Biomolecules

B. Organic nutrients

C. Inorganic nutrients

D. Both B and C

2. Vitamins are classified in how many groups?

A. 2

B. 3

C. 4

D. 6

3. What is the main basis for the classification of the vitamins?

A. Structure

B. Functions

C. Solubility

D. Composition

4. Which vitamin is also known as niacin?

A. Vitamin B3

B. Vitamin E

C. Vitamin B5

D. Vitamin D

5. Deficiency of which vitamin causes rickets?

A. Vitamin B3

B. Vitamin E

C. Vitamin B5

D. Vitamin D

6. Which vitamin is composed a six-member ring attached to 11-carbon side chain?

A. Vitamin B1

B. Vitamin K

C. Vitamin E

D. Vitamin A

7. Which vitamin helps in blood coagulation?

A. Vitamin B1

B. Vitamin K

C. Vitamin E

D. Vitamin A

8. Match the following-

a. Vitamin B12 1. biotin

b. Vitamin B1 2. Ascorbic acid

c. Vitamin C 3. Thiamine

d. Vitamin H 4. cynocobalamine

9. Which of the following is the function of Vitamin A?

A. Development of teeth

B. Maintaining healthy retina

C. Development of soft tissue

D. All of the above

10. Which vitamin acts as a co-enzyme in carboxylase reactions?

A. Thiamine

B. Biotin

C. Niacin

D. Pyridoxine

11. Which enzyme is also known as folic acid?

A. B12

B. Vitamin K

C. Vitamin B5

D. None of the above

12. Which of the following statement is NOT true?

A. Vitamins are classifies according to its structure

B. Biotin works as co-enzyme

C. Vitamin K works for blood coagulation

D. Vitamin E works for healthy functioning of circulatory systems

13. Which vitamin is the component of acetyl-CoA and ACP?

A. B9

B. Vitamin K

C. Vitamin B5

C. All of the above

14. Which vitamin serves as reducing agent?

A. Biotin

B. Folic acid

C. Ascorbic acid

D. Pyridoxine

15. Which vitamin consists of pyrimidine ring attached to thiazole ring?

A. Vitamin B1

B. Vitamin K

C. Vitamin E

D. Vitamin A

ANSWERS:-

1. Organic nutrients

2. 2

3. Solubility

4. Vitamin B3

5. Vitamin D

6. Vitamin A

7. Vitamin K

8. a – 4 b – 3 c – 2 d – 1

9. All of the above

10. Biotin

11. None of the above

12. Vitamins are classifies according to its structure

13. Vitamin B5

 14. Ascorbic acid

15. Vitamin B1

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REFERENCE:- Pankaja Naik- Biochemistry; 4^th edition; page no:- 353-375