Bio lab 2 - Biology lab 2 PDF

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Biology lab 2...

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Know the term used to describe what kind of molecules carbohydrates, proteins, and lipids/fats are (Organic/Biological molecules) Know the purpose for lab 2 (See notes from the board) To determine what? 

Determine Biological Molecules. We are going to test for the prescence of three types of biomolecules in a negative/ positive control setting using Benedicts Reagent (Simple Sugars), Lugol Solution (Polysaccharides), Sudan IV Solution (Lipids/Fats), Biuret Reagent Test (Proteins)

Know the names, forms, and structures for all the biological molecules we studied/observed in lab 2 (Review the highlighted notes that I told you to highlight in your lab manual) o Carbohydrates pg8-9  Carbohydrates are organic compounds. They occur in a variety of

forms ranging from the simple sugars (so called because they have a sweet taste) to the complex, large molecules of glycogen, starch, and cellulose. The latter three are insoluble, with the starch in plants and the glycogen in animals functioning as reserve storage foods. They are called polysaccharides because they are composed of a large number of sugar molecules (glucose in all three of these examples).  Glucose is a very important monosaccharide and sucrose is a very

important disaccharide. Carbohydrates can be identified by their ability to react in specific ways with certain chemical reagents to produce characteristic and easily identified color reactions. Monosaccharides, disaccharides, and polysaccharides require different testing procedures due to their different chemical and physical structure.  Monosaccharide (one simple sugar/glucose molecule)  Disaccharide (two simple sugar/glucose molecules linked

together  Polysaccharide (many monosaccharide/glucose molecules

linked together i.e. cellulose, starch, glycogen o Fats pg9  Dietary fats, which are special kinds of lipids, are made of fatty

acids and glycerol. Fatty acids are organic molecules consisting of a long chain of carbon atoms in which the bonds are tied to hydrogen atoms, except for the terminal carbon, which is attached to an acid, or a carboxylic group (COOH). triglycerides,

three fatty acid molecules bond individually to each of the three hydroxide (-OH) groups of the glycerol

o Proteins  Proteins are the most important of the food molecules. They play a

central role both in structure and function of organisms. They are found in every essential component of the cell, e.g. the nucleus, the cell membrane, the mitochondria, and the ribosomes. Proteins are very large molecules consisting of long chains of amino acids linked together with peptide bonds and containing thousands of atoms, mostly carbon, hydrogen, oxygen, and nitrogen. In some protein molecules sulfur, phosphorus, and even small quantities of heavy metals such as zinc, copper, and iron are all integral parts of the protein structure.

Know the reagents/solutions used to test for each biological molecule o Carbohydrates (two different test for different carbohydrate structures)  Simple Sugar Test (for the presence of simple

sugars/monosaccharides)  Benedict’s reagent is a mixture of sodium carbonate, sodium citrate, and copper sulfate. If this mixture is heated in the presence of simple sugars, copper in the copper sulfate (blue) is changed in a chemical reaction to a chemical that produces red precipitate.  Polysaccharides Test (for the presence of starches and other polysaccharides)  The iodine of the Lugol’s solution absorbs light so that the starch solution is blue-black. But with amylose the light absorption is altered and thus the solution is no longer blue-black. The amylopectin-iodine complex absorbs different light waves and, in this case, a different color is observed. Glycogen yields a blue-black color with the iodine reagent. o Sudan IV Test- Sudan IV is hydrophobic and non-polar. Therefore, Sudan IV will dissolve readily in fats but not in water. Hence, the color will be much deeper if the substance contains fat (to test for the presence of lipids fats) o Biuret Test- Biuret is a compound that is produced when proteins are treated as described in the following procedure (to test for the presence of proteins)...