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Concept 5.5: Nucleic acids store and transmit
hereditary information
Chapter 5-5
The Structure and Function of
Large Biological Molecules
PowerPoint® Lecture Presentations for
• Chromosomes contain one long molecule of
DNA
• Each chromosome contains multiple genes
– Genes are the AA sequences on DNA that
code for individual proteins
NUCLEIC ACIDS
Biology
DNA
RNA
Protein
– Genes are made of DNA, a nucleic acid
Eighth Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
The Roles of Nucleic Acids
• There are two types of nucleic acids:
– Deoxyribonucleic acid (DNA)
The Roles of Nucleic Acids
• There are two types of nucleic acids:
– Ribonucleic acid (RNA)
• provides directions for its own replication
• directs synthesis of messenger RNA
(mRNA)
• carries the code for making one polypeptide
from one gene in the nucleus to ribosomes
in the cytoplasm
• through mRNA, controls protein synthesis
• functions as a part of ribosomes
• is passed from one generation of cells to
the next
• brings amino acids to the ribosomes
• can be used to determine how closely
related organisms are
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 5-26-1
Fig. 5-26-2
DNA
1 Synthesis of
mRNA in the
nucleus
DNA
1 Synthesis of
mRNA in the
nucleus
mRNA
NUCLEUS
mRNA
NUCLEUS
CYTOPLASM
CYTOPLASM
mRNA
2 Movement of
mRNA into cytoplasm
via nuclear pore
1
Fig. 5-26-3
The Structure of Nucleic Acids
DNA
1 Synthesis of
mRNA in the
nucleus
• Nucleic acids are polymers called
polynucleotides
mRNA
NUCLEUS
CYTOPLASM
mRNA
2 Movement of
mRNA into cytoplasm
via nuclear pore
Ribosome
3 Synthesis
of protein
– nucleotides = the monomers of
polynucleotides (DNA & RNA)
• Each nucleotide consists of a nitrogenous
base, a pentose (5-carbon) sugar, and a
phosphate group
• nucleoside = the portion of a nucleotide
without the phosphate group
Amino
acids
Polypeptide
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 5-27ab
Nucleotide Monomers
5' end
5'C
Nucleotide
3'C
Nucleoside
Nitrogenous
base
Phosphate
group
3'C
Sugar
(pentose)
3'C
– Pyrimidines (cytosine, thymine, and uracil)
have a single six-membered ring of C & N
– Purines (adenine and guanine) have two
rings: a six-membered ring fused to a fivemembered ring
5'C
5'C
• There are two families of nitrogenous bases:
3' end
• In DNA, pyrimidines pair with purines
C---G
T---A
(a) Polynucleotide, or nucleic acid
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Fig. 5-27c-1
Nitrogenous bases
The nitrogen in the
nitrogenous base
acts as a proton
acceptor
Nucleotide Monomers
Pyrimidines
• There are two pentose sugars found in nucleic
acids
• In DNA, the sugar is deoxyribose
DNA
Cytosine (C)
Thymine (T, in DNA) Uracil (U, in RNA)
--contains A, T, G, C
• in RNA, the sugar is ribose
Purines
Sugars
RNA
--contains A, U, G, C
Adenine (A)
Guanine (G)
Deoxyribose (in DNA)
Ribose (in RNA)
(c) Nucleoside components: nitrogenous bases
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2
Nucleotide Monomers
Nucleotide Polymers
• Phosphate group
• Attached to the
#5 C on the
sugar
Phosphate
group
5'C
• Acts as a
proton donor &
is the functional
group that
makes DNA &
RNA acids
• Phosphodiester linkages
– Adjacent nucleotides are joined by covalent
bonds that form between the –OH group on the
3′ carbon of one nucleotide and the phosphate
on the 5′ carbon on the next
– These links create a backbone of sugarphosphate units with nitrogenous bases as
appendages
• The sequence of bases along a DNA or mRNA
polymer is unique for each gene
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
The DNA Double Helix
The DNA Double Helix
• A DNA molecule has
two polynucleotides
spiraling around an
imaginary axis, forming
a double helix
• The sugar-phosphate backbones are on the OUTSIDE of
the helix and are held together by covalent bonds
• The nitrogen bases are in
the middle and pair up to
connect the 2 sides using
hydrogen bonds
• In the DNA double
helix, the two
backbones run in
opposite 5′ → 3′
directions from each
other, an arrangement
referred to as
antiparallel
5' end
The complementary
strands are used as
templates to replicate the
DNA, resulting in two
identical copies of the
original DNA
The structure of the DNA
accounts for its function in
transmitting genetic
information to new cells.
A—T
–
C—G
Complementary
base pairing
• van der Waals forces
between the stacked bases
also help to hold the
strands together
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Fig. 5-28
–
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
3' end
DNA and Proteins as Tape Measures of Evolution
Sugar-phosphate
backbones
Base pair (joined by
hydrogen bonding)
Old strands
• The linear sequences of nucleotides in DNA
molecules are passed from parents to offspring
• Two closely related species are more similar in
DNA than are more distantly related species
Nucleotide
about to be
added to a
new strand
3' end
• Molecular biology can be used to assess
evolutionary kinship
5' end
New
strands
5' end
3' end
5' end
3' end
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3
The Theme of Emergent Properties in the
Chemistry of Life: A Review
Quick Quiz
• Higher levels of organization result in the
emergence of new properties
1. In a DNA double helix, a region along one
DNA strand has the following sequence of
nitrogenous bases: 5’ –TAGGCCT- 3’
– Water’s behavior results from interactions of its
molecules
– Chemical groups on carbon skeletons
determine the behavior of larger molecules
3’ –ATCCGGA- 5’
What would be the complementary strand?
– Polymers have properties not found in their
monomers
• Organization is the key to the chemistry of life
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Quick Quiz
Quick Quiz
2. Suppose a substitution occurred in one DNA
strand of the double helix, resulting in :
3. Which of the following pairs of base
sequences could form a short stretch of a
normal double helix of DNA?
5’ –TAAGCCT- 3’
a) 5’-purine-pyrimidine-purine-pyrimidine-3’ with
3’-purine-pyrimidine-purine-pyrimidine-5’
3’ –ATTCGGA–ATCCGGA- 5’
5’
Identify the mismatched pair of nucleotides.
b) 5’-AGCT-3’ with 5’-TCGA-3’
If the modified top strand were replicated, what
would be the complementary strand?
c) 5’-GCGC-3’ with 5’-TATA-3’
d) 5’-ATGC-3’ with 3’-TCGA-5’
e) All of these pairs are correct.
4. Construct a table that organizes the following
terms, and label the columns and rows:
Phosphodiester
linkages
Peptide bonds
Polypeptides
Monosaccharides
Triglycerides
Nucleotides
Glycosidic
linkages
Ester linkages
Polynucleotides
Amino acids
Polysaccharides
Fatty acids
4. Construct a table that organizes the following terms,
and label the columns and rows:
4
You should now be able to:
Fig. 5-UN2a
5. Distinguish between the following pairs:
a) pyrimidine and purine
b) nucleotide and nucleoside
c) ribose and deoxyribose
d) the 5′ end and 3′ end of a nucleotide
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 5-UN2b
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