Carbohydrates Essay, Research Paper

Carbohydrates

Introduction:

Carbohydrates are molecules that contain Carbon, Hydrogen, and Oxygen. The most basic sugar- carbohydrate is the monosaccharide. Carbohydrate molecules are categorized by the number of carbons present in the molecule. Glucose, the most common monosaccharide has six carbons per molecule, which is called a hexose. Carbohydrates also have a 2:1 hydrogen to oxygen ratio. This aids in the condensation and hydrolysis reactions. A condensation reaction occurs when two monosaccharides join by the removal of H2O. During condensation synthesis one monosaccharide losses an OH and the other losses a H. As a result the two monosaccharides bond by forming maltose a disaccharide with a by-product of a free H2O. When three or more monosaccharides or monomer are involved in a condensation synthesis a polymer or polysaccharide is formed with a by product of water. Starch and Glycogen are two common chain polymers.

Just as the removal of water joins carbohydrates together via condensation synthesis, hydrolysis is the reaction using water to break apart Di and polysaccharide. A Di-saccharide is bound by sharing an oxygen with one hydrogen on each opposing side. When H2O is re-introduced via hydrolysis the two monomers in the disaccharide no longer need to share one H2O, and as a result the opposing sides absorb the OH and H and break apart. This reaction is a common theme in the digestion of complex carbohydrates.

Experiment 3: Test for Sugars

We will test five different solutions for presence or absence of reducing sugars using a premixed Benedict s reagent. These dependent variable solutions will be water, glucose , onion juice, potato juice, and starch suspension. When the Benidict s reagent is combined with sugars at a boiling temperature, a color reaction will occur. Our independent variable, Benidict s reagent color is blue.

The negative control will be the combination of water and Benidict s reagent. This sample will undergo all the steps of the test except for the one being tested for i.e. sugars. If the end result is negative color change (blue) , it will thus be determined that the experiment and the Benidict s reagent is not contaminated and the experiment may proceed. The negative control will also serve as a comparison to gauge against the color change in the other four sugar tests.

EXPERIMENT 3: Test for Sugars: TESTS MAT. & METHODS HYPOTHESIS RESULTS

Tube 1 1cm water+2cm Benidict s reagent. No color change

Negative control no color change. Neg-sugar. Blue

Tube 2 1cm glucose solution+ 2cm Benidict s reagent. Boil 5-10 min. Color change due to sugars. Orange+red color, Pos-sugars.

Tube 3 4 drops onion juice+ Fill to 1cm mark water +Fill to 3cm mark Benidict s reagent. Boil 5-10 min. Color change due to sugars Yellow+orange

Pos-sugars

Tube 4 4 drops potato juice+ fill to 1cm mark water +Fill to 3cm mark Benidict s reagent. Boil 5-10 min. Color change due to sugars. Green+blue

Pos-sugars

Tube 5 1cm starch suspension+ Fill to 3cm mark Benidict s reagent. Boil 5-10 min. No color change

due to no simple sugars. No color change Neg-sugar

Blue

Conclusion:

Tube contained water and Benidict s reagent. This experiment was our negative control. Since negative results where acquired we could conclude that our reagent was not contaminated and the experiment could continue. Tube 2 contained glucose. Glucose is a monosaccharide or simple sugar which gave the most color change. Tube 3- onion juice contains both mono and disaccharides , which caused a moderate reaction. Tube 4 contained potato juice which contains very little simple sugars resulting in a mild reaction. Lastly tube 5 contained starch suspension which consists of polysaccharide and no simple sugars, thus no reaction occurred.

Experiment 4: Iodine Test for Starch

When Polysaccharide or starch units are placed in the presence Iodine a reaction occurs. Iodine (brownish in color) will be absorbed by the starch units to form a blue black color.

In this experiment we will test 2 solutions and 2 substances for the presence of starch. Iodine will be the independent variable. Our dependent variable will be water, starch suspension, potato piece, and onion piece.

Our negative control will be the combination of water and iodine. This sample will undergo all the steps of the test except for the one being tested for i.e. starch. If the end result is negative color change (brownish) , it will thus be determined that the experiment and the Iodine is not contaminated and the experiment may proceed. The negative control will also serve as a comparison to gauge against the color change in the other four starch tests.

EXPERIMENT 4: Test for Starch: TESTS MAT & METHODS HYPOTHESIS RESULTS

Tube 1 1cm H2O + 5 drops Iodine No color change due to no starch Negative control

brown color

Tube 2 1cm starch suspension+ 5 drops Iodine Color change due to presence of starch Purple+black color

Pos- starch

Slide 1 2cm by 2cm ultra thin slice of potato. Put on slide, and observe under a microscope the reaction that occurs with the infusion of Iodine Color change due to presence of starch Potato cells show a high absortion affinity in the presence of Iodine. Blue-black color. Pos-starch

Slide 2 2cm by 2cm ultra thin slice of onion. Put on slide, and observe under a microscope the reaction that occurs with the infusion of Iodine Color change due to presence of starch. Onion cells show a low abortion affinity in the presence of Iodine. Black color. Pos-starch

Conclusion:

Tube 1 consisted of Iodine and water. This was our negative control and provided no reaction. Tube 2 consisted of Iodine and starch suspension. Blue black color change can be explained by high presence of Polysaccharide. Slide 3 was a potato slice, that readily absorbed the Iodine into its Polysaccharide rich cells. Lastly the onion slide only lightly absorbed Iodine into its cells. This is due to the fact their is a low presence of starch in onions.

Experiment 5: Starch Structure Test

In this experiment we will be testing the for the products that are formed when starch is put an acidic environment. Our independent variables will be Benidict s reagent and Biuret Reagent . Our dependent variable will be starch and HCL.

The negative control of the experiment will be the mixture of starch, H20, and Benedicts reagent. This sample will undergo all the steps of the test except for the one being tested for i.e. sugars. If the end result is negative color change (blue) , it will thus be determined that the experiment and the Benidict s reagent is not contaminated and the experiment may proceed. The negative control will also serve as a comparison to gauge against the color change in the other four sugar tests.

EXPERIMENT 5: Test for Starch Structure: TESTS MAT& METHOD HYPOTHESIS RESULTS

Tube 1 2cm starch + 2cm H2O. Shake & wait 30 min & add 2cm Benidict s reagent . No reaction. Due to no HCL to break down starch. Negative Reaction

Negative control

Blue color

Tube 2 2cm starch + 2cm HCL. Shake & wait 30 min & add 2cm Benidict s reagent. Boil for 5-10 min. Change of color due to starch and HCL reaction. Green color due to presence of monosaccharides

Tube 3 2cm H2O+2cm HCL

shake & wait 30 min add 2cm biuret reagent. No protiens, No peptides, No reaction or color change. Negative Reaction

Negative control

Blue color

Tube 4 2cm starch+2cmHCL

shake & wait 30 min add 2cm biuret reagent. No color change due to no peptides or protiens. No color change.

Blue.

Conclusion:

Starch goes through structural changes when put in a acid environment of HCL. HCL works as a catalyst which speeds up hydrolysis reactions thus breaking down polysaccharide into mono or disaccharides. Once this reaction took place, the Bennedict s reagent reacted with the mono or disaccharides with a color change of green. The experiments using biuret reagent proved that starch in an acidic environment does not change its molecular structure into peptides.

Error:

All experiments where subject to the same types of errors. These errors could have been any variation of experimental procedures, chemicals, or data.

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