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Chapter 11: DNA and Its Role in Heredity
CHAPTER 11
DNA and Its Role in Heredity
Chapter 11: DNA and Its Role in Heredity
Chapter 11: DNA and Its Role
in Heredity
DNA: The Genetic Material
The Structure of DNA
DNA Replication
The Mechanism of DNA Replication
DNA Proofreading and Repair
Practical Applications of DNA Replication
Chapter 11: DNA and Its Role in Heredity
DNA: The Genetic Material
• In addition to circumstantial evidence, two
experiments demonstrated that DNA is the
genetic material.
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Chapter 11: DNA and Its Role in Heredity
DNA: The Genetic Material
• In one, virulent strain pneumococcus
bacteria DNA genetically transformed
nonvirulent bacteria into virulent bacteria.
Review Figure 11.1
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Chapter 11: DNA and Its Role in Heredity
Figure 11.1
Figure 11.1
figure 11-01.jpg
Chapter 11: DNA and Its Role in Heredity
DNA: The Genetic Material
• In a second, labeled viruses were incubated
with host bacteria.
• Labeled viral DNA entered host cells,
producing hundreds of label-bearing viruses.
Review Figures 11.2 and 11.3
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Chapter 11: DNA and Its Role in Heredity
Figure 11.2 – Part 1
Figure 11.2 – Part 1
figure 11-02a.jpg
Chapter 11: DNA and Its Role in Heredity
figure 11-02b.jpg
Figure 11.2 – Part 2
Figure 11.2 – Part 2
Chapter 11: DNA and Its Role in Heredity
figure 11-03.jpg
Figure 11.3
Figure 11.3
Chapter 11: DNA and Its Role in Heredity
The Structure of DNA
• X-ray crystallography showed that the DNA
molecule is a helix.
Review Figure 11.4
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Chapter 11: DNA and Its Role in Heredity
Figure 11.4
Figure 11.4
figure 11-04.jpg
Chapter 11: DNA and Its Role in Heredity
The Structure of DNA
• DNA is composed of nucleotides, each
containing adenine, cytosine, thymine, or
guanine.
• There are equal amounts of adenine and
thymine and equal amounts of guanine and
cytosine.
Review Figure 11.5
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Chapter 11: DNA and Its Role in Heredity
Figure 11.5
Figure 11.5
figure 11-05.jpg
Chapter 11: DNA and Its Role in Heredity
The Structure of DNA
• Watson and Crick proposed that DNA is a
double-stranded helix with antiparallel
strands, and with bases linked by hydrogen
bonding.
• Their model accounts for genetic
information, mutation, and replication
functions of DNA.
Review Figures 11.6 and 11.7
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Chapter 11: DNA and Its Role in Heredity
Figure 11.6
Figure 11.6
figure 11-06.jpg
Chapter 11: DNA and Its Role in Heredity
figure 11-07a.jpg
Figure 11.7 – Part 1
Figure 11.7 - Part 1
Chapter 11: DNA and Its Role in Heredity
figure 11-07b.jpg
Figure 11.7 – Part 2
Figure 11.7 – Part 2
Chapter 11: DNA and Its Role in Heredity
DNA Replication
• Semiconservative, conservative, and
dispersive models for DNA replication were
hypothesized.
Review Figure 11.8
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Chapter 11: DNA and Its Role in Heredity
figure 11-08.jpg
Figure 11.8
Figure 11.8
Chapter 11: DNA and Its Role in Heredity
DNA Replication
• Meselson and Stahl’s experiment proved
replication of DNA to be semiconservative.
• A parent strand is a template for synthesis
of a new strand.
• Two replicated DNA helices contain one
parent strand and one synthesized strand
each.
Review Figures 11.9 and 11.10
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Chapter 11: DNA and Its Role in Heredity
figure 11-09.jpg
Figure 11.9
Figure 11.9
Chapter 11: DNA and Its Role in Heredity
figure 11-10.jpg
Figure 11.10
Figure 11.10
Chapter 11: DNA and Its Role in Heredity
The Mechanism of DNA
Replication
• DNA polymerase catalyzes nucleotides to
the 3’ end.
• Nucleotides are added by complementary
base pairing with the template strand.
• The substrates, deoxyribonucleoside
triphosphates, are hydrolyzed as added,
releasing energy for DNA synthesis.
Review Figure 11.11
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Chapter 11: DNA and Its Role in Heredity
Figure 11.11
Figure 11.11
figure 11-11.jpg
Chapter 11: DNA and Its Role in Heredity
The Mechanism of DNA
Replication
• The DNA replication complex is in a fixed
location and DNA is threaded through it for
replication.
Review Figure 11.12
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Chapter 11: DNA and Its Role in Heredity
Figure 11.12
Figure 11.12
figure 11-12.jpg
Chapter 11: DNA and Its Role in Heredity
The Mechanism of DNA
Replication
• Many proteins assist in DNA replication.
• DNA helicases unwind the double helix, the
template strands are stabilized by other
proteins.
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Chapter 11: DNA and Its Role in Heredity
The Mechanism of DNA
Replication
• Prokaryotes have a single origin of
replication; eukaryotes have many.
Replication for each proceeds in both
directions from an origin of replication.
Review Figure 11.13
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Chapter 11: DNA and Its Role in Heredity
figure 11-13.jpg
Figure 11.13
Figure 11.13
Chapter 11: DNA and Its Role in Heredity
The Mechanism of DNA
Replication
• An RNA primase catalyzes the synthesis of
short RNA primers, and to which nucleotides
are added.
Review Figure 11.15
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Chapter 11: DNA and Its Role in Heredity
figure 11-15.jpg
Figure 11.15
Figure 11.15
Chapter 11: DNA and Its Role in Heredity
The Mechanism of DNA
Replication
• DNA polymerase action causes the leading
strand to grow in the 5’-to-3’ direction until
replication of that section of DNA is
complete.
• RNA primer is degraded and DNA replaces
it.
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Chapter 11: DNA and Its Role in Heredity
The Mechanism of DNA
Replication
• On the lagging strand, growing in the other
direction, DNA is made in the 5’-to-3’
direction but synthesis is discontinuous:
• DNA is added as short fragments to primers,
then the polymerase skips past the 5’ end to
make the next fragment.
Review Figures 11.16, 11.17 and 11.18
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Chapter 11: DNA and Its Role in Heredity
Figure 11.16
Figure 11.16
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Chapter 11: DNA and Its Role in Heredity
figure 11-17.jpg
Figure 11.17
Figure 11.17
Chapter 11: DNA and Its Role in Heredity
figure 11-18.jpg
Figur
e
11.18
Figure 11.18
Chapter 11: DNA and Its Role in Heredity
DNA Proofreading and Repair
• There is about one error in 106 nucleotide
bases added in DNA replication, repaired by:
proofreading, mismatch repair, and excision
repair.
• DNA repair mechanisms lower the error rate
to about one base in 109.
Review Figure 11.19
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Chapter 11: DNA and Its Role in Heredity
Figure 11.19
Figure 11.19
figure 11-19.jpg
Chapter 11: DNA and Its Role in Heredity
DNA Proofreading and Repair
• Although energetically costly and somewhat
redundant, DNA repair is crucial to the
survival of the cell.
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Chapter 11: DNA and Its Role in Heredity
Practical Applications of DNA
Replication
• The principles of DNA replication can be
used to determine the nucleotide sequence
of DNA.
Review Figure 11.20
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Chapter 11: DNA and Its Role in Heredity
Figure 11.20 – Part 1
Figure 11.20 – Part 1
figure 11-20a.jpg
Chapter 11: DNA and Its Role in Heredity
Figure
11.20 - Part
2
Figure 11.20 – Part 2
figure 11-20b.jpg
Chapter 11: DNA and Its Role in Heredity
Practical Applications of DNA
Replication
• The polymerase chain reaction technique
uses DNA polymerases to repeatedly
replicate DNA in the test tube.
Review Figure 11.21
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Chapter 11: DNA and Its Role in Heredity
Figure 11.21
Figure 11.21
figure 11-21.jpg