Download AMINO ACIDS AND THEIR POLYMERS

05_CTR_ch24 7/12/04 8:20 AM Page 635
Name ___________________________
24.3
Date ___________________
Class __________________
AMINO ACIDS AND THEIR POLYMERS
Section Review
Objectives
• Describe the structure of an amino acid
• Distinguish between peptides and proteins
• Explain how enzymes affect biochemical reactions
Vocabulary
• amino acid
• peptide
• peptide bond
• protein
• enzymes
• substrates
• active site
Part A Completion
Use this completion exercise to check your understanding of the concepts and terms
that are introduced in this section. Each blank can be completed with a term, short
phrase, or number.
© Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reserved.
An
1
is any compound that contains amino and
1.
carboxylic acid groups in the same molecule. The amino acids
2.
commonly found in nature consist of a carboxyl group, an
3.
amino group, a hydrogen atom, and a
2
covalently bonded
to a central carbon atom. The chemical nature of the
3
4.
5.
accounts for the differences in properties of the standard set of 20
6.
naturally occurring amino acids.
7.
4
Two amino acids can react to form a
. In this reaction,
the carboxyl group of one amino acid combines with the amino
5
group from the other amino acid to form a
molecule of
6
8.
9.
bond and a
. When the number of amino acids joined
together in one continuous chain exceeds 100, the resulting
polypeptide is called a
7
.
In cells, proteins often function as
8
. Proteins that
catalyze biological reactions are generally referred to as
9
.
Chapter 24 The Chemistry of Life
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05_CTR_ch24 7/12/04 8:20 AM Page 636
Name ___________________________
Date ___________________
Class __________________
Part B True-False
Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT.
________ 10. The side chains of amino acids are nonpolar.
________ 11. The majority of naturally occurring amino acids are right-handed
stereo isomers.
________ 12. The order in which the amino acids of a peptide molecule are linked is
called the amino acid sequence.
________ 13. Proteins have a characteristic three-dimensional shape that is
determined by the interactions between the amino acids in the protein.
Part C Matching
Match each description in Column B to the correct term in Column A.
Column A
Column B
________ 14. enzyme–substrate
complex
a. a metal ion or small molecule that must be present
for a catalyzed reaction to occur
________ 15. coenzyme
b. the structure that forms when a molecule attaches to
an active site of an enzyme
________ 16. substrate
c. a molecule on which an enzyme acts
Answer the following in the space provided.
17. The formula of aspartame (Nutra-Sweet) is shown below. Aspartame is a
dipeptide of phenylalanine and aspartic acid. Identify (1) the central carbons,
(2) the side-chain groups, (3) the peptide bond, (4) the free amino end of the
dipeptide, and (5) the free carboxyl end of the dipeptide. (Note that the free
carboxyl group of phenylalanine is modified to a methyl ester in aspartame.)
COOH
@
@
CH2
CH2
@
@
H2N 2 C 2 C 2 NH 2 C 2 C 2 O 2 CH3
@
@
#
#
H O
H O
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Core Teaching Resources
© Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reserved.
Part D Problem