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Chapter 2
The Chemical Composition of Cells
CHAPTER OUTLINE
An introduction to basic chemistry
Atoms are the smallest particles of elements
Each atom has an atomic number and an atomic mass
Acids and bases
Acids and bases dissociate when dissolved in water
A solution’s acidity or alkalinity is expressed in terms of pH
Organic compounds
Sugars, starches, and cellulose are examples of carbohydrates
Focus On: How Did Life Begin?
Process of Science: Miller and Urey’s experiment in chemical evolution
Plants and the Environment: Acid Rain
Plants and People: Phytochemicals and Human Health
CHAPTER OBJECTIVES
1. Describe the basic structure of an atom and explain ionic, covalent, and hydrogen
bonds.
2. Discuss the properties of water, and explain the importance of water to life.
LECTURE OUTLINE
I. What is an element?
A. How many naturally occurring elements are on Earth?
II. What are atoms?
A. Where (specifically) are protons, electrons, and neutrons found? What is the charge
of each one?
III. What are chemical compounds?
A. What are chemical bonds? What determines the number of bonds that a particular atom
can form?
B. Ionic bonds
1. What are ions and how are they formed from neutral atoms?
D. What is a hydrogen bond?
IV. What is the difference between inorganic and organic substances?
V. Describe the biological importance of water.
A. Why should you suspect that water is important to life?
B. What are three distinct functions water has in living systems?
C. The biological properties of water are due to its polarity.
1. Water can exist in all three phases (solid, liquid, and vapor) on the earth,
VI. What are acids and bases?
A. Give examples of strong and weak acids and bases.
VII. Carbohydrates are sugars or macromolecules made from sugars.
A. Give some examples of carbohydrates.
1. What monosaccharide makes up starches and cellulose?
2. How do starches and cellulose differ in structure and function in plants?
3. How do humans use starches and cellulose?
VIII. Lipids are nonpolar compounds.
A. Give some examples of lipids.
B. How are fats and oils used in cells?
C. What is the basic structure of fats and oils?
1. What is glycerol?
IX. Proteins are large molecules.
A. What is the importance of proteins?
B. What is the structure of proteins?
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4. What is a catalyst?
5. What is the energy of activation for a reaction?
X. Nucleic acids
What are nucleic acids?
A. How are nucleic acids used in the cell?
B. What are the building blocks of nucleic acids?
1. What are nucleotides?
XI. What is energy?
A. What is the difference between potential energy and kinetic energy?
B. What is thermodynamics?
KEY TERMS
acid, p. 30
adhesion, p. 29
atom, p. 24
activation energy, p. 37
active site, p. 37
covalent bond, p. 26
deoxyribonucleic acid
(DNA), p. 38
disaccharide, p. 33
electron configuration, p. 25
ionic bond, p. 26
isotope, p. 24
kinetic energy, p. 39
lipid, p. 34
molecule, p. 26
TEACHING TIPS
1. There are six elements found in biomolecules that form the word CHNOPS. Carbon,
hydrogen, and oxygen are in all biomolecules, nitrogen and phosphorous are in nucleic acids,
and nitrogen and sulfur are in proteins. For discussion, ask the question, “What three features
do these elements share which contribute to their importance to organic molecules?” They
2. Capillary action: for a lab activity or for a lecture demonstration, use three glass or plastic
tubes of different diameter and colored water. Place the tubes in a beaker with the colored
3. Define hydrophilic and hydrophobic and describe how dissolved ions and polar