* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download File
Survey
Document related concepts
Western blot wikipedia , lookup
Endomembrane system wikipedia , lookup
Peptide synthesis wikipedia , lookup
Model lipid bilayer wikipedia , lookup
Protein adsorption wikipedia , lookup
Ribosomally synthesized and post-translationally modified peptides wikipedia , lookup
Cell-penetrating peptide wikipedia , lookup
Bottromycin wikipedia , lookup
Self-assembling peptide wikipedia , lookup
Photosynthetic reaction centre wikipedia , lookup
Metalloprotein wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Fatty acid metabolism wikipedia , lookup
Transcript
Lab 3 carbohydrates Monosaccharides 3 Disaccharide Formation 4 Glycogen: a Polysaccharide It represents a storage form of glucose. Glycogen synthesis and degradation occurs primarily in the liver and in the skeletal muscle, although other tissues (e.g., cardiac muscle) may store smaller quantities. 5 How the Body Uses Sugars Glycogen exists in the body as a reservoir of available energy that is stored in the chemical bonds within individual glucose monomers. Hydrolysis of glycogen, as occurs during periods of fasting, leads to release of the glucose monomers into the blood, thereby preventing blood glucose from decreasing to dangerously low levels. Glucose is often called “blood sugar” because it is the major monosaccharide found in the blood. 6 How do we determine if carbohydrates are present in a solution? A molecule is oxidized if it loses an electron or hydrogen atom and is reduced when it gains an electron or hydrogen atom. Collectively, the two processes are referred to as a redox reaction because when one molecule is oxidized, another is reduced. How do we determine if carbohydrates are present in a solution? • Benedict’s reagent • Tests for the presence of reducing sugars. – Sugars that contain aldehyde groups that are oxidized to carboxylic acids. • Benedicts reagent (CuSO4 / citrate) – They are classified as reducing sugars since they reduce the Cu2+ to Cu+ which forms as a red precipitate, copper (I) oxide. How do we determine if carbohydrates are present in a solution? – Aldehydes, RCHO, can be oxidized to carboxylic acids, RCO2H,under aqueous conditions. REDUCING SUGARS • All common monosaccharides are reducing sugars. • The disaccharides maltose and lactose are reducing sugars. • The disaccharide sucrose is a non-reducing sugar. Lugol’s Iodine (IKI) test for the presence of starch • Iodine dissolved in an aqueous solution of potassium iodide reacts with starch producing a deep blue-black color. • This reaction is the result of the formation of polyiodide chains from the reaction of starch and iodine. • The amylose, or straight chain portion of starch, causes the dark blue/black color. The amylopectin, or branched portion of starch, causes the formation of an orange/yellow hue. Proteins Proteins Proteins account for about 50 percent of the organic material in the body (17 percent of the body weight), and they play critical roles in almost every physiological process. Proteins are composed of carbon, hydrogen, oxygen, nitrogen, and small amounts of other elements, notably sulfur. They are macromolecules, often containing thousands of atoms. 14 Proteins are Made of Amino Acids 15 Peptide Bonds 16 How do we test for peptides in solution? Biuret test Copper and base The Biuret reagent, regularly colored blue, is used to identify proteins. When the copper ions (Cu2+) in the reagent interact with peptide bonds, a violet color is produced. Ror the interaction between Cu2+ and the peptide bonds to result in a color change, a minimum of 4-6 peptide bonds is required. Lipids Lipids are molecules composed predominantly (but not exclusively) of hydrogen and carbon atoms. These atoms are linked by nonpolar covalent bonds. Thus, lipids are nonpolar and have a very low solubility in water. Lipids can be divided into four subclasses: fatty acids, triglycerides, phospholipids, and steroids. Lipids are important in physiology partly because some of them provide a valuable source of energy. Other lipids are a major component of all cellular membranes, and still others are important signaling molecules. Test for Fats (lipids) Sudan IV Like lipids, the chemical Sudan IV is not soluble in water; it is, however, soluble in lipids. In this test dark red Sudan IV is added to a solution along with ethanol to dissolve any possible lipids. If lipids are present the Sudan IV will stain them reddish-orange (positive test). Nucleic Acids Nucleotides 22 How do we test for the presence of nucleic acids in solution? • Dische diphenylamine test – DNA can be identified chemically with the Dische Diphenylamine test. – Acidic conditions convert deoxyribose to a molecule that binds with diphenylamine to form a blue complex. – The intensity of the blue color is proportional to the concentration of DNA. - +