This is because HCl breaks starch back down into its component monosaccharides glucose, in this case. Amylase is an enzyme that removes glucose molecules from starch. Both plants and animals use amylase when digesting starch. Unfortunately, amylase cannot break the beta-bonds which hold the glucose molecules together in cellulose.
If it could, we'd be able to eat hay. Based on this information, can you figure out what our results should be if we tested amylase-treated starch and amylase-treated cellulose solutions for reducing sugars?
Organic Molecules These are complex, carbon-containing molecules associated with living organisms. Most also contain hydrogen and oxygen. There are five major types: carbohydrates, lipids, proteins, nucleic acids, and vitamins. We covered the first three types in lab. A review of our carbohydrate test data is provided on this page. Click the molecule types above to link to the associated review material.
Interpreting Benedict's Reagent Results Benedict's reagent starts out aqua-blue. If proteins are present a chemical reaction occurs between the copper ions and the protein molecules. The chemical reaction causes the Biuret solution to turn from a light blue to purple if proteins are present.
The presence of lipids can be determined using Sudan III indicator. Sudan Indicators are fat-loving molecules that are colored. When testing a solution for lipids there are two results you should be looking for:.
Does the dye migrate toward one of the layers? A positive result will see the lipid layer sitting on top of the water layer and the lipids layer will have a red-orange color. The Dische Diphenylamine Test is used for determining the presence of nucleic acids. The presence of DNA will turn a clear solution blue. The more DNA present the darker the color.
Another nucleic acid, RNA, will turn green. CNS Bio. C Lunch. Benedict's solution is an irritant. Avoid contact with skin and eyes. Take care when heating in a boiling water bath. Test for starch Add iodine solution to the food being tested. Iodine solution is an irritant. Test for proteins The biuret test is used to detect peptide bonds in proteins.
Biuret solution A is corrosive. You may leave the markings on them until the final clean up procedure of the day. Do not spill the KOH — it is extremely caustic. Rinse your skin if it comes in contact with KOH.
Perform the Protein Test: Reproduce this table in your lab book and complete it with your observations. When your observations are complete, carefully wash and rinse the tubes following the instructions in Part I.
Lipids are a class of molecules that are not soluble do not dissolve in water. They are composed of the molecular building blocks of glycerol and three fatty acids. Fatty acids come in two major types, saturated and unsaturated.
This difference is due to the presence of particular types of bonds within the fatty acid molecule see figure and affect the shape and characteristics of the overall lipid containing these fatty acids. You may want a review of lipids. Use gloves and avoid contact with Sudan IV as it is considered a possible carcinogen. Immediately wash your skin with soap and plenty of water if you come in contact with the solution.
Sudan IV test for lipid: Reproduce this table in your lab book and complete it with your observations. The darker the stain, the more lipid is present. When your observations are complete, carefully dispose of any remaining Sudan IV solution in the container provided by your instructor. Always use gloves and do not move the container if there is a danger of spilling. Enrique was a new employee. He wanted to stay. Today, there was a problem and he had to figure out something fast to solve it.
He knew that if he did, the manager would be really pleased and his job was guaranteed. The customer claimed to be on a reduced-calorie diet and was not happy about the extra calories consumed. There was more at stake than one unhappy customer, though.
The manager told Enrique that many of their customers were diabetic and consuming sugar-laden soda could alter their blood-sugar chemistry in a dangerous way. They could not allow those customers to be harmed. If the diet soda dispenser did have regular soda, then did the regular soda dispenser have diet?
What about the Dr. Pepper dispenser? That, at least, tasted like Dr. Pepper, so it was OK- or was it? What a mess! Should they throw all the soda in the dispenser out and start again? Or was there some way of determining if the soda was being dispensed correctly? If they could determine what the problem was, they could save the business money and not waste the soda products.
Enrique knew that most soda had high fructose corn syrup in it but diet soda had sugar substitutes in it: Substitutes that were not sugar but fooled your taste buds into believing it was. Just the other day, in science lab, Enrique had run some tests on solutions in order to determine their compositions. One of the tests was for detecting monosaccharides in solution! He knew his science teacher would still be in the classroom at this time and the school was barely a 5 minute walk from the restaurant.
He could solve the mystery in under 30 minutes! Enrique quickly told his manager his plan and grabbed some cups of soda, which he labeled, so he could tell which dispenser they came from, then headed out. Enrique quickly ran to the school lab and got permission to run his experiment. Help Enrique set up an experiment to test the soda. Perform the Appropriate Test: Reproduce this table in your lab book and complete it with your observations.
DO NOT allow ethanol to come in contact with the hotplate. Ethanol is very flammable. Figure 1: The molecular and macro structures of sucrose, starch, lipids, and proteins. Part I: Controlled Experiments to Identify Organic Compounds Indicators are chemicals that change color when chemical conditions change, such as pH, or when a chemical reaction takes place producing a colored molecule.
Proteins The cell relies on proteins for very many functional reasons. Procedure Obtain 5 test tubes and number them 1 — 5.
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