Carbohydrates

Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen atoms, typically with a hydrogen: oxygen atom ratio of 2:1, as in water. They are one of the primary sources of energy for the body. Carbohydrates can be classified based on their structure and complexity into three main types: monosaccharides, disaccharides, and polysaccharides.

1. 1. Monosaccharides:

       

      • • Structure: Monosaccharides are the simplest form of carbohydrates and consist of a single sugar molecule. They have the general formula (CH2O)n(CH2O)n, where nn can range from 3 to 7.

       

      • • Examples: Glucose, fructose, and galactose.

       

      • • Function: They serve as the building blocks for more complex carbohydrates and are a quick source of energy.

       

       

2.Disaccharides:

• • Structure: Disaccharides are composed of two monosaccharide molecules linked together by a glycosidic bond.

• • Examples: Sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (two glucose molecules).

• • Function: They are broken down into monosaccharides during digestion and provide a quick source of energy.

3.Polysaccharides:

• • Structure: Polysaccharides are long chains of monosaccharide units linked together. They can be branched or unbranched.

• • Examples: Starch, glycogen, and cellulose.

• • Function: They serve as energy storage (starch in plants and glycogen in animals) and structural components (cellulose in plant cell walls).

Proteins

Proteins are large, complex molecules made up of amino acids, which are organic compounds containing an amine group (−NH2−NH2), a carboxyl group (−COOH−COOH), and a unique side chain. Proteins play a crucial role in virtually all biological processes.

1.Amino Acids:

• • Structure: There are 20 different amino acids, each with a unique side chain (R group) that determines its properties and function.

• • Types: Essential amino acids (cannot be synthesized by the body and must be obtained from the diet) and non-essential amino acids (can be synthesized by the body).

2.Protein Structure:

• • Primary Structure: The sequence of amino acids in a polypeptide chain.

• • Secondary Structure: Local folding of the polypeptide chain into structures such as alpha-helices and beta-sheets, stabilized by hydrogen bonds.

• • Tertiary Structure: The overall three-dimensional shape of a single polypeptide chain, stabilized by various interactions, including hydrogen bonds, ionic bonds, and disulfide bridges.

• • Quaternary Structure: The arrangement of multiple polypeptide chains into a functional protein complex.

Lipids

Lipids are a diverse group of hydrophobic molecules that include fats, oils, waxes, phospholipids, and steroids. They are important for energy storage, cell membrane structure, and signaling.

1.Types of Lipids:

• • Triglycerides: Composed of one glycerol molecule and three fatty acids. They are the main form of stored energy in animals.

• • Phospholipids: Composed of two fatty acids, a glycerol molecule, and a phosphate group. They are a key component of cell membranes.

• • Steroids: Composed of four fused carbon rings. Cholesterol is a well-known steroid that is a precursor to other steroids, including hormones.

2.Fatty Acids:

• • Saturated Fatty Acids: Have no double bonds between carbon atoms and are typically solid at room temperature.

• • Unsaturated Fatty Acids: Have one or more double bonds and are typically liquid at room temperature. They can be further classified into monounsaturated (one double bond) and polyunsaturated (multiple double bonds).

Understanding the structure and types of these macronutrients is fundamental to grasping their roles in nutrition and metabolism.