Lab Exercise 6
Purpose the purpose of this experiment was to perform test to detect the presence of carbohydrates, proteins, lipids, and nucleic acids. Explain the importance of a positive and a negative control in biochemical test. Use biochemical test to identify an unknown compound. Background
Most organic compounds in living organisms are carbohydrates, proteins, lipids, and nucleic acids they are called macromolecules. Each of these macromolecules is made of smaller subunits. These subunits are linked by dehydration synthesis. Dehydration synthesis is an energy requiring process in which a molecule of water is removing and the two subunits are boded covalently. This energy releasing process is called hydrolysis. The subunits of macromolecules are held together by covalent bonds and have different structure and properties. For example, lipids made of fatty acids have many C-H bonds and relatively little oxygen; while proteins are made of amino acids have groups NH2 and carboxyl groups. In an experiment we have two or more treatments, an unknown solution to be identified, and two controls to provide standard for comparison, a positive controls and a negative control. The positive control contain the variable for which you are testing, it react positively and demonstrates that test’s ability to detect what you expect. For example if you testing for protein is a solution known to contain protein, a positive reaction shows that your test reacts correctly, it ‘also shows you what a positive test look like. A negative control does not contain the variable for which you are searching. It contains only the solvent often distilled water with no solute and does not react in the test. A negative control shows you what a negative result looks like. Carbohydrates are molecules of carbon, hydrogen and oxygen in a ratio of 1:2:1 the chemical formula for glucose is C6 H12 O6.
Carbohydrates are made of monosaccharides, or a simple sugar, paired monosaccharide from disaccharides. Many monosaccharide such as glucose and fructose are reducing surgar, meaning that they poses free aldehyde or ketone groups that reduce weak oxidizing agents such as the copper in benedicts reagent Glucose monosaccharide
(6.1)Material and Methods in the process or exercise of measuring the Benedict’s test we were used the following material and how we used them to conduct the experiment. We obtained seven test tubes and number them from one to seven, then add to each tube the material to be tested table 6.1. Add 2 ml of Benedict’s solution to each tube. Place all of the tube in a gently boiling water-bath for 3 minutes and observe color changes during this time, after 3 minutes, remove the tubes from the water bath and give the tube a little bit of time to cool down the temperature, and record the color. Result in table 6.1. and when you finished dispose of the contents of each tube as instructed. Starch is just a different word for carbohydrates, the stuff you find in bread and potatoes and pasta, which your body converts to glucose for energy. The words 'carbs' and 'carbohydrates' are very popular now, so everybody knows what they are. But until a few years ago they were seen as very scientific terms, and the layman's term was starch. You will therefore find it a lot in older books and texts. The Benedict’s reducing sugar is a commonly used test to detect carbohydrates is the Benedict's test for reducing sugars such as glucose and fructose. Benedict's reagent, containing sodium bicarbonate, sodium citrate, and copper sulfate, is added to a solution and heated. The Benedict's test identifies reducing sugars based on their ability to reduce the cupric ions to cuprous oxide at high pH values (basic solutions). Cuprous oxide is green to reddish orange. A green solution indicates a small amount of reducing sugars, while a reddish-orange solution indicates an...