Question

What Was - starch hydrolysis results in formation of Formed glucose, fructose etc. based on the enzym Upon I mode of action. The color of Fehlings Digestion? sovhon turns to yedbi cause the Sugarne - copped (11) to copper in fenungs sowho PROBLEMS 1. What purpose does amylase serve in the hydrolysis of starch? Why did the color of the iodine test change over time? Be specific about the reaction that is occurring (substrate and product). 2. Should there be a difference between the reaction of starch with Fehling's reagent before hydrolyzed and after it was hydrolyzed? If so, why? 3. Draw the structure for glucose and identify the functional group that makes glucose a reducing sugar.

Answer 1

(a) Amylase reacts with starch, breaking it in disaccharide maltose which further broken down to give glucose units. Function of amylase is to catalyze the hydrolysis of starch into glucose. iodine test is used to test for the presence of starch. Starch turns into an intense blue-black colour when aqueous solutions of the triiodide anion added, that is due to the formation of an intermolecular charge-transfer complex. But when starch is hydrolyzed using amylase starch -iodine complex breaks down and colour also goes off. amylase - amylase maltose – Starch glucose (b) Starch is a polymeric form, in which no free reducing groups are present, So, starch gives negative test with fehling reagent. But, when starch is hydrolyzed, glucose units are released. Glucose is reducing sugar having free aldehydic group which gives positive test with fehling reagent. Aldehyde group of glucose is oxidised by complexed copper ions to form acid. The red copper (1) oxide precipitates, which gives indication for the redox reaction. Glucose can exist in aqueous solution as a ring shape or as an open chain molecule.

(c) Glucose is an aldose, i.e., its open-chain form contains an aldehyde group. Aldehydes can be easily oxidized to carboxylic acids, so glucose is reducing sugar. І н -он онен ньон нон Н.c— он