Tag: carbohydrate and its test

Carbohydrates are the most abundant biomolecules found on the face of the earth. This is so because every year plants and algae through the process of photosynthesis convert more than 100 billion metric tons of carbon dioxide and water to cellulose and other products for use by the plants. Some bacteria undergo photosynthesis but it is anoxygenic as bacteria has only pigment system I. Thus, the correct answer is option A.

Carbohydrates (CHO) - These are the principle energy storage molecules. They contain carbon (C), hydrogen (H), and oxygen (0) in a 1:2:1 ratio and are classified according to their size into monosaccharide, disaccharide, polysaccharide.

Monosaccharides are simple sugar having single chain or single ring structure which contains 3-7 carbon atoms. Example is glucose with 6 carbons, 12 hydrogens, and 6 oxygens.

Disaccharides: Double sugars are formed by dehydration reaction between 2 monosaccharides glucose + glucose ------ - > maltose + water. Disaccharides are too large to pass through cell membranes and must be digested to simple sugar units by hydrolysis (add water).

Polysaccharides are long chains of simple sugar molecules. The two major molecules of importance are starch, which is used for storage form for carbohydrate fuel in plants and glycogen, which is used for storage form for carbohydrate fuel in animals.

Function: It is ready source of cellular fuel & cellulose, is used for structural support in plants and carbohydrates help form cell receptors for recognition. Hence, option C is correct.

Carbohydrates are made up of C: H: O, having H and O in the ratio of 2:1 and the general formula is (CH2O)n. Sources of carbohydrates in our food are cereals and pulses. The caloric value is 4.1 kcal/g.

Most common monomer used in polysaccharides is glucose. For example, starch, cellulose, glycogen all are polymers derived from glucose. Plants synthesize carbohydrates as glucose or fructose and store in other form like starch. The type of linkage between glucose molecules is different in storage and structural polysaccharides. The linkage in storage polysaccharides is $\alpha$- whereas $\beta$-linkage is present between glucose molecules in structural polysaccharides.

Plant cell is characterised by presence of a cellulosic cell wall which is dead at maturity. The cellulose is a structural polysaccharide made up of glucose molecules linked by $\beta$-glycosidic linkage.

Hydrolases catalyse hydrolytic reactions. Some of the important hydrolases includes amylases, sucrase, lactase, maltase, protease, esterase etc. 

C_nH_2nO_n is a general formula of monosaccharides. Monosaccharides are the simplest carbohydrates which cannot be hydrolyzed into smaller units. They usually have 3-7 carbon atoms per molecule. They are the compounds of carbon, hydrogen, and oxygen in which hydrogen and oxygen occur in the ratio of 2:1 as in a molecule of water. Thus, they are also known as hydrates of carbon. 

Disaccharides are oligosaccharides which are formed by condensation of two monosaccharides. Lactose is a disaccharide. It is made up of two hexose molecules, glucose, and galactose. Lactose is also known as milk sugar because it is found in milk. It is a reducing sugar. Thus, the correct answer is B