Interactives. British and Metric Conversions Abont h 30 Exercise 4: Identificati

Question

Interactives. British and Metric Conversions Abont h 30 Exercise 4: Identification and Quantification of Organic Molecules clements. The enzymes of a cell are also protein molecules. Proteins are constructed of long chains of amino acids joined together by peptide linkages. The sequence of the amino acids in any give protein molecule is determined by the genetic material, the DNA, of the cell. By virtue of the large number of amino acids that enter into making a single protein molecule, by virtue of the infinite numbers of combinations of different amino acids that can be formed, and because of the reactivity of side groups of the individual amino acids, an unlimited variety of sizes, configurations, and kinds of physical propertics are shown by protein molecules. In this exercise, you will use the Lowry procedure to detcrmine the concentration of protcin in solution. The denaturation of protein by mercury salts will also be demonstrated. Nucleic acids are composed of repeating nucleotides (i.e, they are polymers of nucleotides) in which the sequence of the nitrogenous bases varies. RNA and DNA differ in two fundamental ways: 1) RN/A contains uracil instead of thymine, and 2) DNA contains deoxyribose as its sugar instcad of ribose. This difference in sugar molecules allows for the determination of DNA with diphenylamine reagent. This exercise will demonstrate the reactivity of DNA and RNA with diphenylamine PROCEDURE It is suggested that the following sequence be followed in performing the experiments in this exercise This will avoid crowding and will assure that all experiments are completed in a timely manner A. Carbohydrates 1. Benedict's Test This test is used to detect the presence of most monosaccharides and disaccharides. Benedict's solu tion reacts with the aldehyde or ketone groups in the linear forms of monosaccharides. Any disac charide that can open its ring form and resume its linear form will also react positively to Benedict's solution. Sucrose is an exception because it cannot open and resume the linear form. Therefore, sucrose does not react with Benedict's solution. Most monosaccharides and disaccharides cause reduction and are referred to as reducing-sugar When Benedict's solution is mixed with a reducing sugar and heated, a red precipitate is formed Benedict's solution contains sodium bicarbonate, sodium citrate, and copper sulfate. After heating with a reducing sugar, the divalent copper (Cu·') of copper sulfate is red ned to the monovalent copper (Cu') of cuprous oxide (Cu2O), which forms the precipitate Benedict's solution is blue and when the precipitate forms, depending on the concentration of reducing sugars, various colors develop from green to yellow to orange to red. A yellowish-green indicates a low concentration, whereas an orange-reddish color indicates a high concentration of reducing sugars. Therefore, the Benedict's test can provide both qualitative and quantitative Materials 8 test tubes Bencdict's solution 1% glucose 1% fructose 1% maltose 1% sucrose 1% glycogen Water 500 ml beaker Test tube rack Tongs Hot plate Procedure a. Label 8 clean test tubes, I through 8, add 5ml distilled water/tube. b. Place 8 drops of Benedict's solution into each of the eight test tubes.

Explanation / Answer

Benedict's test is used for the presence of simple sugars like glucose. In the presence of glucose, fructose, maltose and solution would turn brick red/orange. This will be the final color after heating. The conclusion is the presence of a reducing sugar. Water, Glycogen, starch, sucrose will give a negative test and blue colour will be observed

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.