Eleven Standard >> Biomolecules | Part - 2

Biomolecules: Polysaccharide & Fats

Polysaccharides are large, complex carbohydrates composed of repeating units of simple sugar molecules. They play important roles in various biological processes. 

Polysaccharides are classified based on their structural and functional properties. The classification of polysaccharides  typically includes the following categories:

1. Homopolysaccharides: These are polysaccharides composed of a single type of monosaccharide unit. Examples include:

   • Starch: Composed of glucose units and serves as a storage polysaccharide in plants.

   • Glycogen: Composed of glucose units and serves as a storage polysaccharide in animals.

   • Cellulose: Composed of glucose units and forms the structural component of plant cell walls.

2. Heteropolysaccharides: These are polysaccharides composed of more than one type of monosaccharide unit. Examples include:

   • Heparin: Composed of repeating units of glucuronic acid and N-acetylglucosamine. It functions as an anticoagulant in the human body.

   • Chondroitin sulfate: Composed of repeating units of glucuronic acid and N-acetylgalactosamine. It is a component of cartilage and connective tissues.

Fats, referred to as triglycerides, belong to the category of lipids. Their structure consists of a glycerol molecule linked to three fatty acid molecules. Here are some key points to understand about fats:

1. Structure: Fats consist of a glycerol molecule bonded to three fatty acid molecules through ester linkages. Fatty acids can be described as chains of hydrocarbons that are relatively long, and at one end of the chain, there is a carboxyl group (-COOH).

2. Functions: Fats serve several important functions in living organisms:

   • Energy Storage: Fats serve as a highly efficient storage form of energy. They are stored in specialized cells called adipocytes and can be broken down and metabolized to release energy when needed.

   • Insulation and Protection: Fats are also involved in providing thermal insulation and protection to vital organs by acting as a cushioning material.

   • Hormone Synthesis: Certain fats, such as cholesterol, are precursors for the synthesis of steroid hormones in the body.

3. Saturated and Unsaturated Fats: Fatty acids can be classified as saturated or unsaturated based on their chemical structure:

   • Saturated Fats: Saturated fatty acids have single bonds between all carbon atoms in their hydrocarbon chain. They are typically solid at room temperature and are found in animal sources like butter and fatty meats.

   • Unsaturated Fats: Unsaturated fatty acids have one or more double bonds in their hydrocarbon chain. They are usually liquid at room temperature and are found in plant sources like vegetable oils. Unsaturated fats can further be classified as monounsaturated (one double bond) or polyunsaturated (multiple double bonds).

4. Importance of Essential Fatty Acids: The CBSE syllabus may also mention the importance of essential fatty acids. These are fatty acids that the body cannot synthesize and must be obtained from the diet. Examples include omega-3 and omega-6 fatty acids, which are necessary for various physiological functions.