Investigation of Action of Saliva and 3M HCl in Two Carbohydrates Solutions.

Title : Investigation of Action of Saliva and 3M HCl in Two Carbohydrates Solutions.
Objective : To investigate the action of saliva and 3M hydrochloric acid in two carbohydrate solution.
Result :
Table 1 : The presence of starch and reducing sugar in the solution

Observation
Conclusion
Solution A
Benedict’s test : The transparent blue solution turns into opaque brick-red precipitate

Iodine’s test : The clear colourless solution turns into transparent yellowish-brown solution. The pure colour of the solution is clear colourless solution and the transparent yellowish-brown colour is the iodine’s colour.
There is presence of reducing sugar whereas absence of starch
Solution B
Benedict’s test : The transparent blue solution remain unchanged

Iodine’s test : The clear colourless solution turns into opaque blue-black solution
There is absence of reducing sugar whereas presence of starch

Table 2 : The effect of hydrochloric acid and saliva in different temperature
Tube
Contents
Temperature (°C)
Benedict’s test

After 5 min (from test tube 1-4 into 1’-4’)
After 35 min (from test tube 1-4 into 1’-4’)
1
10ml solution B
1ml saliva
37
The transparent blue solution turns into opaque greenish-yellow solution
The transparent blue solution turns into opaque reddish-orange solution
2
10ml solution B
1ml 3M HCl
37
The transparent blue solution remain unchanged
The transparent blue solution remain unchanged
3
10ml solution B
1ml 3M HCl
95
The transparent blue solution remain unchanged
The transparent blue solution turns into translucent light brown solution
4
10ml solution B
1ml saliva
95
The transparent blue solution remain unchanged
The transparent blue solution remain unchanged

Discussion :
1. In the experiment, the enzyme amylase was involved in saliva.
2. The enzyme act as a catalyst in the experiment and it lowers the activation energy needed and increase the rate of reaction. Most enzyme are proteins, and their catalytic action results from their complex structure. Enzyme hydrolyses the starch suspension which is a polysaccharide into maltose and maltose which is disaccharide into glucose which is monosaccharide when hydrochloric acid was added into solution B. This is because solution B was hydrolysed and the H+ ions present break down the bond in between molecules of the solution B.
4. Since the substance is starch, starch undergo hydrolysis into reducing sugars in presence of acids. The acid protonates the glycoside oxygen, which gives it a positive charge. In order to neutralize this positive charge, the oxygen pulls electrons away from one of the carbons, neutralizing the oxygen's positive charge but creating a carbocation. The starch is made up of single glucose molecules and it is a long-chain polysaccharide. When starch is hydrolysed with hydrochloric acid, then the starch will forms monomers and disaccharides of glucose.
5. Optimum temperature is the temperature at which an enzyme produces a highest reaction rate for a specific reaction. The tertiary structure is altered by breaking old and forming new attractions when the temperature is increased or decreased. The changes of the shape of the active site may cause the substrate cannot fit as easily and the rate of reaction will decrease. The optimum temperature of the saliva enzyme is 37°C. Hence, when the solution B is heating in the water bath with 37°C. Therefore, the solution B is completely broken down by the saliva enzyme. Thus, when the solution B is heating in the water bath with 95°C, the salivary amylase which present in saliva content denatured. Because high temperature will cause molecules to vibrate more violently, then break down the bond holding the tertiary structure and the 3D structure of saliva enzyme is also broken. The active sites of enzyme are altered, hence the salivary amylase enzyme losses it catalytic functions and finally denatured. As a result, there is no reaction between sugar and Benedict’s solution.
6. a. The product of solution B predicted in the experiment which hydrolysed by hydrochloric acid at a high temperature is glucose and maltose. Glucose is monosaccharide whereas maltose is disaccharide.
b. The structure of glucose contains single reducing sugar unit whereas the structure of maltose contains two reducing sugar unit which also known as two monosaccharide or two glucose units. The chemical formula of glucose is C6H12O6. This empirical formula is shared by other sugars, called hexoses-6 carbon sugars. Maltose contain primarily carbon atoms flanked by hydrogen atoms and hydroxyl groups (H-C-OH).
7. The basis of test used in the experiment is Benedict’s test and iodine’s test. The Benedict’s test was carry out to show the present of sugar. The reducing sugar hydrolysed the blue copper ions (II) in Benedict’s solution into red-brown copper (I) ions, which is insoluble solution. As a conclusion, red-brown precipitate is produced. However, the iodine’s test is carry out to test the present of starch. Iodine is found in the iodine solution which reacts with starch and form a poly-iodide complex with starch. Hence, the opaque blue-black solution is formed.
8. In the experiment, solution B is more complex than solution A. Because the solution A contain only the reducing sugar but the solution B being starch suspension. Starch also contain a largest number of glucose unit and more complex structure. Carbohydrate A is a monosaccharide when it shows a positive result in Benedict’s test whereas the carbohydrate B is the storage of polysaccharide starch when it shows a positive result in iodine test. As a reference, the polysaccharides are polymers of monosaccharide.
9. Solution A is a reducing sugar, solution B is starch suspension. Starch may digest by the amylase and broken down by a high temperature heating in acidic condition. The reactivity of enzyme reach maximum at optimal temperature, 37°C and neutral pH value which is between pH 6.5 – 7.