A man cannot digest carbohydrate. The enzyme deficient is -
Ans. is 'b' i.e., Amylase o Principal enzyme involved in digestion of dietary carbohydrate is amylase.Digestion of carbohydrateso The most abundant carbohydrate in our food is starch. The other forms of carbohydrate which are consumed in substantial amounts are sucrose and lactose.o Starch is a polysaccharide composed entirely of glucose units linked by 1,4- alpha linkage and 1, 6 branching points. What it means that carbon atom -1 of a glucose unit is linked to carbon atom - 4 of the adjacent glucose unit, and that bond is of alpha - type. At the branching points, carbon atom-1 is linked to carbon atom-6 of the adjacent glucose unit.o Digestion of starch starts in the mouth itself by salivary amylase (ptylin). But the hydrolysis by salivary amylase cannot proceed much because the optimal pH for the reaction is 6-7 which is very different from the highly acidic environment of the stomach. The process is resumed by 'pancreatic amylase' in the small intestine. Amylase attacks only internal, 1-4 alpha glucose-glucose bondsQ but spares 1-6 linkages and terminal 1-4 alpha linkages. Hence the products of starch hydrolysis are maltose (a disaccharide, two glucose residues linked by 1:4 a bonds), maltoriose (a trisaccharide, three glucose residues linked by 1:4a bonds), and alpha limit dextrins (Polymers of glucose containing 8 glucose molecules with 1-6 a linkages).o Both salivary1 and pancreatic amylases are activated by Cl-Qo Further digestion of starch derivatives occurs by the enzymes (oligosaccharidases) present in the brush border of small intestinal epithelial cells. Maltase (a-glucosidase) breaks 1:4 linkages in maltose and maltotriose and releases glucose (two molecules of glucose from maltose and three molecules of glucose from maltotriose). Isomaltase (a- limit dextrinase) breaks 1:6 a linkages of alpha-limit dextrin and releases glucose. Isomaltase (a-limit dextrinase) is the only enzyme that attacks 1: 6a linkage.o Sucrose is hydrolysed into fructose and glucose by sucrase (an enzyme present in brush border of intestinal epithelium). Lactose is hydrolysed into galactose and glucose by lactase (b-glucosidase). Trehalase hydrolyzes trehelose (a 1:1 a - linked dimer of glucose) into two glucose molecules. Trehalose is found in mushrooms.About other optionso Pepsin and trypsin are invloved in protein metabolism.o Lipase is involved in fat metabolism.
Lipase
Amylase
Pepsin
Trypsin
Digestion and Absorption