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Bio110
Lab 3: Basic Chemistry
A. Carranza
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
oxygen
carbon
hydrogen
nitrogen
calcium
phosphorus
chlorine
sulfur
potassium
sodium
magnesium
iodine
1ron
all other elements
PERCENT (weight)
(100% total)
62
20
10
3.0
2.5
1.14
0.16
0.14
0.11
0.10
0.07
0.014
0.010
0.756
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
Hydrogen
Carbon
Nitrogen
Oxygen
Electron vacancies in orbital
Number of possible bonds
1. List and describe the three types of bonds that atoms form.
Bond
Description
Covalent
Ionic
Hydrogen
(polar)
Bio110
Lab 3: Basic Chemistry
A. Carranza
2. Indicate whether the following symbols represent atoms, or molecules. If molecules, indicate if
it is a compound molecule.
Atom, Molecule, or Compound?
Atom, Molecule, or Compound?
Symbol
Symbol
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?
_
Bio110
Lab 3: Basic Chemistry
A. Carranza
Bio110
Lab 3: Basic Chemistry
A. Carranza
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.
B.
C.
D.
Benedict’s test for simple carbohydrates
Lugol’s Iodine test for complex carbohydrates (starch)
Sudan IV test for lipids
Ninhydrin test for proteins
Bio110
Lab 3: Basic Chemistry
A.
1.
A. Carranza
Tests for carbohydrates
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.
Solution
Describe color change or reaction
**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.
Solution
Describe color change or reaction
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.
Solution
Describe color change or reaction
Bio110
Lab 3: Basic Chemistry
A. Carranza
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.
Solution
Describe color change or reaction
Summary table
1. Fill in the table below for the biological molecules covered in class. Give an example of each.
Monomer
Polymer
Carbohydrate
Example
Polypeptide
Lipid
Nucleic Acid
2. Describe the four structural levels in proteins.
Level
Description
Primary
Secondary
Tertiary
Quaternary