Chapter 3: The Molecules of Cells
Copyright 0 2015 Pearson Education, Inc. 15
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Guided Reading A ctivities
Big idea: Introduction to organic compounds
Answer the following questions as you read modules 3.1—3.3:
1. Is this molecule an organic compound? Briefly explain your answer.
H—C—C—OH
Alcohol
Yes, it is an organic compound because of the carbon and hydrogen present in the molecule.
2. We are a carbon-based life form. List three properties of carbon that make it an ideal element
from which to construct a wide variety of complex molecules.
Carbon can form four covalent bonds because it needs four electrons to fill its valence shell.
Carbon-based molecules can vary in the number of carbon atoms. Carbon can form covalent
bonds with atoms other than H, which leads to a great diversity in molecules.
3. What is meant by a molecule’s “carbon skeleton” and how can carbon skeletons vary?
The carbon skeleton refers to the number and arrangement of carbon atoms in a molecule.
4. An unidentified molecule is found in a sample of water near a chemical plant. An initial analysis
finds that the molecule contains only carbon and hydrogen. What type of molecule is this? This
type of molecule is a hydrocarbon because it has only carbon and hydrogen.
5. Two molecules that have the same molecular formula but a different structure would be referred
to as a(n)
a. saturated fat
b. hydrogenated oil
c. polypeptide
d. isomer
Chapter 3: The Molecules of Cells
6. The molecule in question 1 is ethyl alcohol. The oxygen atom in ethyl alcohol forms a polar
covalent bond with the hydrogen atom. What functional group is found on ethyl alcohol and
does ethyl alcohol readily interact with water? Briefly explain your answer.
The functional group is a hydroxyl group. Ethanol readily interacts with water because the
hydroxyl group imparts polarity to the ethanol, which allows it to be attracted to water.
7. Complete the table that illustrates the different functional groups.
Hydroxyl
Carbonyl
Carboxyl
Amino
Phosphate
Methyl
Structure
—OH
c=o
—COOH
—NH2
—OP032-
—CH3
8. Which is the only functional group that is nonpolar?
a. Methyl group
b. Carboxyl group
c. Phosphate group
