Carbohydrates, Proteins, Vitamins and Minerals

From WikiEducator

Jump to:navigation, search

Carbohydrates, Proteins, Vitamins and Minerals

By Dr. Mohd. Amirul Islam

Chapter Outline


  1. Introduction
  2. Learning Objectives
  3. Carbohydrates
    1. Sources of Carbohydrates
    2. Structure of Carbohydrates
    3. Classification of Carbohydrates
    4. Importance of Carbohydrates
    5. Functions of Carbohydrates
    6. Carbohydrates Deficiency Diseases
  4. Proteins
    1. Sources of Proteins
    2. Structure of Proteins
    3. Classification of Proteins
    4. Importance of Proteins
    5. Functions of Proteins
    6. Proteins Deficiency Diseases
  5. Vitamins
    1. Classification of Vitamins
    2. Vitamin A (Ratinol)
    3. Vitamins D (Cholecalciferol)
    4. Vitamin C (Ascorbic acid)
    5. Vitamin B1 (Thiamine)
    6. Vitamin B2 (Riboflavin)
  6. Minerals
    1. Kinds of Minerals
    2. Sources and Functions of Minerals
    3. Mineral Deficiency Diseases
  7. Let's Sum Up
  8. Key Points
  9. Glossary
  10. Practice test
  11. Answer to SAQs
  12. References and Further Readings


There are seven main classes of nutrients that the body needs. These are carbohydrates, proteins, fats, vitamins, minerals, fiber and water. It is important to consume these seven nutrients on a daily basis to build and maintain health. Deficiencies, excesses and imbalances in diet can produce negative impacts on health, which may lead to diseases such as cardiovascular disease, diabetes, scurvy, obesity, or osteoporosis as well as psychological and behavioral problems. According to the reports of the United Nations World Health Organization (WHO: 1996), more than starvation the real challenge in developing nations today is malnutrition-the deficiency of micronutrients (vitamins, minerals and essential amino acids) that no longer allows the body to ensure growth and maintain its vital functions. We will discus about the sources, classification, importance and deficiency diseases of carbohydrates, proteins, vitamins and minerals in this unit.

Learning Objectives
After reading this chapter, you are expected to learn about:

  • Describe about carbohydrates, their sources, structure and classification;
  • Explain the properties of carbohydrates, and their importance and functions in human body;
  • Identify carbohydrates deficiency diseases;
  • Describe about proteins, their structure, bond and classification;
  • Explain the properties of proteins and their functions in human body;
  • Identify the protein deficiency disease;
  • Describe about vitamins and their classifications;
  • Explain the properties, sources and functions of vitamins;
  • Identify the vitamin deficiency disease;
  • Describe about minerals and their kinds;
  • Identify the sources and explain the function of minerals; and
  • Recognize the mineral deficiency diseases.


Carbohydrates are the polyhydroxy organic compounds made up of carbon, hydrogen and oxygen in which the ratio of hydrogen and oxygen hydrogen is 2:1 exactly as H2O (2:1). (image:comment.gif: Can you add some more sentences to this part?)

Sources of Carbohydrates

The main sources of carbohydrates are plants, e.g., starch (storage forms carbohydrate of chlorophyll containing plants), sugars, cereals, potatoes, legumes, millets, roots and other vegetables. Sugars are found in fruits, juice, cane, honey, palm, milk, etc.

(image:comment.gif: Can you add some more sentences to this part?)

angular cheilitis see cheilitis treatment cheilitis treatment chelitis chelitis

Structure of Carbohydrates

Fig. 1: Structure of glucose molecule.
Classification of Carbohydrates

Carbohydrates may be classified into the following four major groups -

  1. Monosaccharides: Monosaccharides are the simplest form of carbohydrates. All carbohydrates are reduced to this state before absorption and utilization. They contain three to six carbon atoms. General formula is Cn(H2O)n.
  2. Disaccharide: Disaccharides Consist of two covalently joined monosaccharide units. They are produced as two molecules of the same or different monosaccharides on hydrolysis. General formula is Cn(H2O)n-1, e.g., lactose, sucrose, maltose etc.
  3. Oligosaccaharides: Oligosaccaharides consist of few number (2-6) of monosaccharide units e.g., glycoproteins.
  4. Polysaccharides: Polysaccharides are composed of many molecules of monosaccharides linked together. General formula is (C6 H10 O5)x. e.g., Glycerole.
Importance of Carbohydrates

  1. Carbohydrates, such as energy yielding compounds D-Ribose, are the structural elements of nucleic acid and coenzymes.
  2. Act as intermediates in hexose monophosphate stant.
  3. D-Lyxose, a constituent of a lyxoflavin isolated from human muscle.
  4. D-glucose carried out by the blood and used in tissues.
  5. D-fructose can be changed to glucose in the liver and intestine and used in the body.
  6. Glycosides are important in medicine.
  7. Hexosamines is used as antibiotic.
  8. Monosaccharides are important constitute of nucleotides and nucleic acids.
  9. Disaccharides act as an intermediate in the digestion, important as a dietary constituent and major source of energy in the diet.
  10. Starch and glycogen serve as temporary stores of glucose in plants and animals respectively.

Functions of Carbohydrates

  1. Glucose act as energy yielding compounds, the major fuel of the tissue, constitutes the structural material of the organism, converted to other carbohydrates having highly specific functions.
  2. Glycogen acts as important storage of food material of the organism.
  3. Play a key role in the metabolism of aminoacids and fatty acids.
  4. Act as protective function-mucosubstance.
  5. Act as intermediates in respiration and carbohydrates metabolism e.g., (trioses).
  6. Participate in lipid synthesis.
  7. Pentoses - Synthesis of nucleic acid; Some co-enzymes (e.g., NAD, FAD, FMN, etc.); ATP, ADP, AMP, and also synthesis of polysaccharides.
Carbohydrates Deficiency Diseases


Proteins are complex organic compounds. They are macromolecules or bio molecules composed of amino acids linked by peptide bond. The constituent elements of proteins are carbon (54%), hydrogen (7%), nitrogen (16%), oxygen (22%) and some may contain sulpher (1%) or phosphorus (0.6%). They are macromolecules of high MW and consisting of chains of amino acids e.g., hemoglobin, albumin, globulin, enzymes, etc.

Sources of Proteins

Peas, beans, poultry, cereals, lentils, milk, cheese, eggs, meat, wet and dry fishes, pulses, and nuts. (image:comment.gif: Can you add little more in this sub-section?)

Structure of Protein

The basic unit of the protein molecule is amino acids .The protein molecules are composed of the union of a large number of amino acids. There are over 10,000 proteins in the human body. They all composed of different arrangements of the main 20 fundamental amino acids. The sequence of amino acids in each protein is specific and is genetically controlled by the DNA of the cell.

Chemical Structure

The synthesis of protein molecule takes place by the union of the-NH2 group of one amino acid with the-COOH group of another. Elimination of water is known as condensation and the linkage (bond) formed is a covalent carbon-nitrogen bond, called a peptide bond. The remaining part of amino acid is known as R group or side chain. In this way dipeptide or polypeptide is formed.

(image:comment.gif: Check this figure??)

CH2-CH.NH2 + HNH.CH2COOH H2N-CH.CH2-CO-NH.CH2COOH+H2O  COOH Amino group Carboxyl group

Fig. 2: General formula of an amino acid.

According to the modern views, the structure of protein is considered by several level of organization.

1. Primary level - peptide bond is formed by the amino acids. They are linked by carboxyl group of one amino acid with the -amion group of another amino acid through disulphide bonds and other covalent modification.

  			      O		        O 		         O	

HN – CH – C – NH – CH – C – NH – CH – C ----
 		          R1		R2		    R3		

Fig. 3: Primary structure.

2. Secondary level - peptide bonds are folded which indicates a coiled structure (e.g., globular proteins). In this folding the carboxyl and amino groups of the peptide chains are linked by hydrogen and disulfided bonds. Such folding is known as the secondary structure of the protein.

3. Tertiary structure - when the globular protein consists of a series of single helix. These models will have elongated structures with a larger axial ratio (length: breadth). The structure in their dimensions is maintained by covalent or other bonds and described as tertiary structure.

4. Quaternary structure - In this structure, there are several monomer units, each with appropriate primary, secondary and tertiary structures may combine through non-covalent interactions e.g., hemoglobin contains four subunits identical in pairs.

Classification of Proteins

Proteins may be classified in the following ways -

According to Structure

  1. Fibrous type with elongate molecule e.g., keratin
  2. Pounded type with globular molecule
  3. Intermediate type.

According to Composition

  1. Simple proteins -e.g., albumins, globulins, histones etc.
  2. Conjugated proteins - e.g., nucleoproteins, lipoproteins, chromoprotiens, flavoproteins.
  3. Derived protein e.g., metproteins, peptones.

According to function

  1. Structural type - eg., collagen, -keratin ,mucoproteins.
  2. Enzymes type - eg. trypsinase, carbonylase, glutaminase.
  3. Hormones type-e.g., insulin, glucagon.
  4. Transplant type - e.g., hemoglobin, serum albumin.
  5. Protective type - e.g., antibodies, thrombin, fibrinogen.
  6. Contractile type - e.g., myosin, actin.
  7. Storage type - e.g., casein, ovalbumin.
  8. Toxins type - e.g., diphtheria toxin, snake venom.
Properties of Proteins

Function of Proteins

Protein Deficiency Diseases


Vitamins may be defined as organic compounds occurring in small quantities in different natural foods and necessary for the growth and maintenance of good health in human beings and certain experimental animals.

They cannot be synthesized in the body but supplied by the diet to the human body. Plants produce all vitamins but animal (human) stores them. Some are produced in the body e.g. Provitamin carotene is converted into vitain A in the body and Vit. D is produced in the body in presence of ultraviolet radiation.

Classification of Vitamins

Vitamins are classified into two groups.

1. Fat - soluble vitamins

Fat-soluble vitamins are soluble in fats and fat solvents. They are insoluble in water. So these are utilized only if there is enough fat in the body e.g., vitamin A, D, E and K.

2. Water -soluble vitamins

Water-soluble vitamins are (heterogeneous group) soluble in water and so they cannot be stored in the body. 11 types of vitamins are included in this class e.g., thiamine, riboflavin, pyridoxine, cyanoccobalamine, niacin, pantothenic acid, biotin, folic acid and ascorbic acid, para-amino benzoic acid, and choline.

Vitamin A (Ratinol)


Source of Vitamin A

Liver, heart, kidney, milk, codliver oils, fishliver-oils, butter, eggs, carrots, cabbage, vegetables, green leaves, mangoes, potatoes tomatoes, spinach, papaya etc.


Vitamin A Deficiency Diseases

Vitamins D (Cholecalciferol)


Source Fish liver oils e.g., cod liver oil, halibut - liver oil etc. Butter, milk, eggs, liver. In sub coetaneous tissue, 7 dihydrocholesterol is conveted to vitamin D by UV light.


Deficiency Disease

Causes Rickets (directive bone growth) in childless, osteomalacia in adults, disturbs calcium and phosphorous absorption.

Vitamin C (Ascorbic acid)



Guava, amla, green chilli, amaranth leaves, citrus fruits, green vegetables, potatoes, tomatoes, cheese, milk etc.


Deficiency Diseases

Vitamin B1 (Thiamine)



Rice polishing, dried yeast and wheat germ are rich sources of vit. B1. Whole cereals like wheat, oats, legumes, oil seeds and nuts are good sources. Milled cereals, vegetables, fruits, meat and fish are poor sources. On milling, vit. B1 is lost from cereals.


Deficiency Diseases

VitaminB2 (Riboflavin)



Milk, liver, kidney, muscle, butter, chicken, fish, yeast, cheese, raw egg, white grains, green vegetable such as spinach, peanuts, fruits such as apple, orange etc. Functions

Deficiency Diseases



(image:comment.gif: Check this part, particularly the gm per day)

Minerals are inorganic substances that serve a variety of functions such as cofactors in enzyme-catalyzed reactions, in the regulation of acid-base balance, in nerve conduction and muscle irritability, and as structural elements in the body. Each mineral is required in specific amounts ranging from y to gm per day. Some of the more important of these are calcium, phosphorus, sodium, potassium and iron.

Kinds of Minerals

Minerals may be divided arbitrarily into 2 groups.

  1. Macro minerals: The minerals, which are required in amounts greater than 100 mg/ day.
  2. Micro minerals: The minerals, which are required in amounts less than 100 mg/ day.

Source and Function of Minerals

Macro Minerals

Source and Function

Micro minerals

Source and Functions

Mineral Deficiency Diseases

Self-Assessment Questions (SAQs) - 1
Multiple choice questions. Choose the correct answer.

1. The unit of Carbohydrates is

a) Disaccharide
b) Monosaccharide
c) Oligosaccharide
d) Polysaccharide.

2. Disaccharide consists of

a) Two molecules of monosaccharedes
b) Three molecules of monosaccharides
c) Four molecules of nonosaccharides
d) Five molecules of monosaccharides.

3. The basic unit of protein molecule is

a) Peptides
b) Amino acid
c) Allanylglycine
d) Albumines.

4. Which vitamin is soluble in fat solvent

a) Thiamin
b) Biotin
c) Vitamin A
d) Folic acid.

5. Which vitamin cannot stand cooking or canning

a) Biotin
b) Vitamin D
c) Folic acid
d) Ascorbic acid.

6. The mineral are required in amounts greater than 100 mg/ day is known

a) Micro molecule
b) Mineral
c) Mineral
d) Macro molecule.

7. Calcium is found in

a) Sprouts
b) Dark green tea
c) Cheese
d) Tea


Practice Test

Short questions

1. What do you mean by carbohydrates?
2. What are the diseases caused in deficiency of Carbohydrates?
3. What do you mean by proteins?
4. What do you mean by vitamins?
5. What are the fat-soluble vitamins, water-soluble vitamins and where are they found?
6. What are the diseases created by the deficiency of vitamin A, C and B1?
7. What do you mean by minerals?
8. What do mean by macro and micro minerals?

Analytical Questions

1. Describe the structure of Carbohydrates.
2. Classify the Carbohydrates.
3. What are the properties, sources and functions of vitamin A, B1, and C?
4. Briefly describe properties, some functions and daily requirements of ascorbic acid and folic acid.
5. Discuss the diseases, which are occurred in mineral deficiency.

Create a book