Chapter 2
The Chemical Level of Organization
Outline and Objectives
INTRODUCTION
1. Consider how atoms bond together in the body to form molecules.
2. Discover how atoms and molecules release or store energy in processes known
as chemical reactions.
3. Discover how water is involved in nearly every chemical reaction.
4. Define matter and mass.
HOW MATTER IS ORGANIZED
Chemical Elements
5. Identify the principal chemical elements of the human body by their names and
chemical symbols.
Structure of Atoms
6. Describe each component of an atom in terms of its relative position, charge, and mass.
Atomic Number and Mass Number
7. Explain how the atomic number of an atom determines its chemistry because of the amount of attraction by the set number of nuclear positive charges for
negative electrons of other atoms.
8. Explain how mass number is related to radioisotopes and atomic weight.
9. Give examples of radioisotopes that are used to determine body tissue structure and function.
Atomic Mass
10. Describe the standard unit for measuring the mass of atoms and their
subatomic particles.
11. Explain why the an element’s atomic weight can be slightly less than the mass number of its smallest stable isotope.
Ions, Molecules, Free Radicals, and Compounds
12. Distinguish among ions, molecules, free radicals, and compounds.
13. Describe the effects of free radicals on health.
CHEMICAL BONDS
14. Describe the significance of the valence shell electrons.
15. Explain the octet rule.
Ionic Bonds
16. Explain why and how an atom can lose or gain electrons, and what the
resulting balance between numbers of electrons and protons produces, as with
sodium and chlorine.
17. Note that when the attraction for electrons (electronegativity) between
adjacent atoms is very different, one will pull electrons from the other, which
produces oppositely charged ions that are attracted to each other and thus
form an ionic bond.
18. Describe what happens to most ionic molecules when put into water.
Covalent Bonds
19. Note that when atoms have a more similar attraction for external electrons,
they share pairs of electrons (one from each atom) to form each single bond
until all atoms in a molecule effectively fill their outer shells.
20. Describe what happens to the distribution of electrons and charge in a
covalent bond when the atoms have slightly different attractions for the
electrons, as with carbon and oxygen, or in water molecules (distinguish
between nonpolar covalent and polar covalent bonds).
Hydrogen Bonds
21. Describe the strength of the bond formed when a hydrogen atom covalently
bound to one atom is also strongly attracted to an atom on a nearby
molecule.
22. Describe the effect on the overall shape of a large molecule due to a great
number of hydrogen bonds between different parts of that molecule.
Chemical Reactions
23. Define a chemical reaction.
24. Explain the law of conservation of mass.
Forms of Energy and Chemical Reactions
25. Define energy and distinguish between potential and kinetic energy.
26. Discuss chemical energy and explain the law of conservation of energy.
Energy Transfer in Chemical Reactions
27. Compare and contrast exergonic and endergonic reactions.
28. Explain how activation energy is required to produce a chemical reaction and
how concentration and temperature influence the rate of reaction.
Catalysts
29. Describe the role of catalysts in chemical reactions.
Types of Chemical Reactions
Synthesis Reactions - Anabolism
30. Give an example of synthetic reactions that occur in the body and note that
they usually require energy from a molecule called ATP.
Decomposition Reactions - Catabolism
31. Emphasize that catabolic reactions are used to obtain energy from food that is
stored in a molecule called ATP.
Exchange Reactions
32. Describe what is meant by an exchange reaction.
Reversible Reactions
33. Note that most chemical reactions in the body are reversible because they are
performed by special molecules called enzymes.
Oxidation-Reduction Reactions
34. Describe the removal of electrons from a molecule and their coupled transfer
to another molecule in terms of dehydrogenation reactions used to obtain
energy from food.
INORGANIC COMPOUNDS AND SOLUTIONS
35. Distinguish between inorganic and organic compounds.
Inorganic Acids, Bases, and Salts
36. Indicate the general properties of acids, bases, and salts, as well as how they
are related in chemical reactions.
Solutions, Colloids, and Suspensions
37. Distinguish among mixtures, solutions, colloids, and suspensions.
38. Explain the terms used to designate the constituents of a solution.
39. Describe how solutions are expressed by percent and in units of moles per
liter.
Water
40. Explain the importance of water in living systems.
Water as a Solvent
41. Explain the properties of water that make it an excellent solvent.
Water in Chemical Reactions
42. Distinguish between hydrolysis and dehydration synthesis.
High Heat Capacity of Water
43. Explain the reason for the high heat capacity of water.
44. Discuss the high heat of vaporization of water.
Cohesion of Water Molecules
45. Explain how the cohesion of water molecules creates a high surface tension
and what that means to the body.
Water as a Lubricant
46. Describe the lubricating effects of water in the body.
Acid-Base Balance: The Concept of pH
47. Define pH in terms of hydrogen and base (hydroxide) ion concentration
relative to water.
Maintaining pH: Buffer Systems
48. Define a buffer in terms of its ability to prevent large changes in [H+] due to
strong acids and bases, in addition to the general mechanism.
49. Use carbonic acid as an example of the response of a buffer to the addition of
H+ or base (OH-) to show the overall [H+] does not change.
ORGANIC COMPOUNDS
Carbon and Its Functional Groups
50. List the properties of carbon that make it particularly useful to living
organisms.
51. Describe the functional groups of organic compounds.
Carbohydrates
52. List the major forms of carbohydrates (sugars, starches, glycogen, and
cellulose), and describe their functions.
53. Discuss the general rule for carbohydrates in that there is one carbon atom for
each water molecule.
Monosaccharides and Disaccharides: The Simple Sugars
54. Discuss what is meant by a simple sugar.
55. Discuss how a disaccharide is formed.
Polysaccharides
56. Discuss the role of glycogen in the body.
Lipids
57. Discuss the chemical makeup and properties of lipids.
Triglycerides
58. Discuss the properties of triglycerides.
59. Distinguish among saturated, monounsaturated, and polyunsaturated fats.
Phospholipids
60. Describe the structure of phosphlipids.
Steroids
61. Describe the structure of steroids.
62. Discuss the role of cholesterol in steroid functioning.
Eicosanoids and Other Lipids
63. Describe the structure and function of eicosanoids.
64. List other types of lipids.
Proteins
65. List and discuss the functional protein groups in the body.
Amino Acids and Polypeptides
66. Describe the basic amino acid structure and how amino acids are joined to
form polypeptides.
Levels of Structural Organization in Proteins
67. Describe how a chain of amino acids interacts with itself to produce the four
levels of structural organization and provide examples of where these are seen
in anatomy.
Enzymes
68. Discuss the naming of enzymes.
69. Describe the properties of enzymes.
70. Describe the general operation of enzymes in terms of catalysis and the
conditions needed to execute essential chemical reactions of metabolism.
71. Discuss galactosemia in terms of enzyme activity.
Nucleic Acids: Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA)
72. Note the two general types of nucleic acids and their role in heredity and
protein production.
73. Discuss the structure of the four nitrogen bases and their interaction in the
structure of the double helix.
74. Discuss the technique of DNA fingerprinting.
75. Discuss the differences between DNA and RNA.
Adenosine Triphosphate
76. Discuss the structure and function of ATP.
77. Briefly discuss the phases of cellular respiration.