Bio110 Lab 3: Basic Chemistry A. Carranza

Transcription

1 NAME Basic Chemistry The following chart lists the important elements found in cytoplasm by weight. On the chart, fill in the symbol and the number of electrons found in each element Use the periodic table of the elements on the next page for the electron number..element SYMBOL ELECTRON NUMBER PERCENT (weight) (100% total) oxygen 62 carbon 20 hydrogen 10 nitrogen 3.0 calcium 2.5 phosphorus 1.14 chlorine 0.16 sulfur 0.14 potassium 0.11 sodium 0.10 magnesium 0.07 iodine ron all other elements If an element has 44 electrons, do we automatically know how many protons are present in the atom? How many? List the number of electrons required to fill the outer orbitals and how many bonds each of the following elements will form. Element Electron vacancies in orbital Number of possible bonds Hydrogen Carbon Nitrogen Oxygen 1. List and describe the three types of bonds that atoms form. Bond Description Covalent Ionic Hydrogen (polar)

2 2. Indicate whether the following symbols represent atoms, or molecules. If molecules, indicate if it is a compound molecule. Symbol Atom, Molecule, or Compound? Symbol Atom, Molecule, or Compound? H NaOH H2 HCl H2O H2SO4 O2 Fe NaCl Mg 3. What does the ph scale measure? 4. Would an acidic solution have low or high ph value? 5. How many atoms are present in H2S04? 6. How many elements are present in H2S04? 7. What is an ion? 8. If an atom of sodium forms an ion, what will be its charge? 9. If an atom of fluorine forms an ion, what will be its charge? 10. Why do elements form bonds? _

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4 Macromolecules All living organisms are composed of only four major groups of macromolecules. Each type has a unique chemical structure and function within the cell. Macromolecules are made up of smaller subunit monomers which can be linked to form chains called polymers. Polymers, in tum, can be broken down into subunit monomers. This is part of the metabolic of process occurring within all life forms. A. Carbohydrates contain mostly carbon, hydrogen and oxygen and serve as a source of quick energy for life. The smaller carbohydrate molecules are known as sugars, while the larger carbohydrate molecules are known as polysaccharides. B. Lipids, also containing carbon, hydrogen, and oxygen. They function as storage of excess energy-in cells, and are commonly called fats. They are also used for insulation, cushioning and one form of lipid (phospholipids) are used to make cell membranes. C. Proteins, made of carbon, hydrogen, oxygen, and nitrogen and perhaps some other atoms such as iron, sulfur or iodine have two major types of functions. Some form much of the internal structure of the cell, while others function as enzymes in controlling cell metabolism. D. Nucleic acids, made of carbon, hydrogen, oxygen, nitrogen and phosphorus form the genetic code (deoxyribonucleic acid or DNA) and function in the synthesis of protein (ribonucleic acid or RNA) Substances found in cytoplasm can be identified as belonging to one of the major groups of organic molecules by various chemical tests. Conveniently enough, many color indicators have developed that react with specific forms of macromolecules. This is how the prepared microscope slides we use in class are stained. In this exercise you will perform some of these chemical tests and then use these tests to identify some unknown solutions. You will perform chemical tests for the Following: A. Benedict s test for simple carbohydrates B. Lugol s Iodine test for complex carbohydrates (starch) C. Sudan IV test for lipids D. Ninhydrin test for proteins

5 A. Tests for carbohydrates 1. Benedicts test for simple sugars The presence of simple sugars can be detected by the Benedict's test. Place 8 drops of Benedict's solution in a test tube, add about 10 ml of glucose solution. After adding two boiling chips** place it in a boiling water bath for about three minutes. Remove and allow the tube to cool for two minutes. Repeat this procedure using 8 drops of Benedict's solution, two boiling chips and 10 ml of water (not sugar solution) as a "control" to compare against the results from the sugar solution. Record all results and observations in the chart below. **Boiling chips are a safety precaution which should be used with all rapid heating within a confined vessel to prevent rapid boiling over. They do not interfere with the reaction. B. Lugol s Iodine test for starches The presence of starch can be shown by the iodine test. Place 5 ml of starch solution in one test tube and 5 ml of water in another. To each add 2 drops of Lugol's iodine solution. Record your results. C. Sudan IV tests for fats Place 5ml of water in a test tube and add a very small quantity of Sudan IV dye. Record results. Next, add 1ml of known fat or oil and shake. Note what happened to the Sudan N dye.

6 D. Test for proteins 1. Ninhydrin test for protiens Protein molecules are complex and contain many different amino acids. Color tests for amino acids have been devised, but the Ninhydrin method is general test for proteins. Add three to five drops of Millon's reagent to 5 ml of protein or albumin (egg white) solution. Add two boiling chips and heat it in the water bath for 5 minutes. Carefully observe the tube during the boiling process. Remember to run a "control" with water instead of protein. Record results. Summary table 1. Fill in the table below for the biological molecules covered in class. Give an example of each. Monomer Polymer Example Carbohydrate Polypeptide Lipid Nucleic Acid 2. Describe the four structural levels in proteins. Level Description Primary Secondary Tertiary Quaternary