Download DNA Ch 9

GENETIC INFORMATION - 1. OVERVIEW
• Storage of Genetic Information
– Structure of DNA
Ch 9
• Making Copies of Genetic Information
– Replication of DNA
Ch 9 – DNA
Ch 11 & 12 - Cells
• Using Genetic Information to Make Cell
Structures and Regulate Energy Use
– Process of Gene Expression
Ch 10
• An Overview of Information Flow in a Cell
– Gene Transcription
DNA => RNA
– Translation
RNA => Protein
– Proteins – cell structures & tools (F10.8, p. 175)
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transcription
rRNA mRNA tRNA
+ proteins
ribosomes
tRNA
amino acids
translation
modification
degradation
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Chapter 9
• DNA: The Molecule of Heredity
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Discovery That Genes Are
Made of DNA
• Transformed Bacteria Revealed the Link
Between Genes & DNA
– Transformed bacteria
(F9.1 p. 150)
– Unnumbered Figure 1 Pyrimidine nucleotides
(p. 151)
– Unnumbered Figure 2 Purine nucleotides (p.
151)
Copyright © 2005 Pearson Prentice Hall, Inc.
Bacterial strain(s) injected into mouse
Living
R strain
Living
S strain
Heat-killed
S strain
Living R strain,
heat-killed
S strain
Results
Conclusions
R strain does
not cause
pneumonia.
S strain causes
pneumonia.
Heat-killed S
strain does not
cause pneumonia.
A substance from
heat-killed S strain
can transform the
harmless R strain
into a deadly
S strain.
Structure of DNA
• DNA: Composed of Four Nucleotides
• DNA: Double Helix of Two Nucleotide Polymers
– X-ray diffraction of DNA - Rosalind Franklin
(F9.2 p. 152)
– Watson-Crick model of DNA structure
– The discovery of DNA
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(F9.3 p. 153)
(FE9.1 p. 154)
phosphate
base = adenine
sugar
phosphate
sugar
base = guanine
Structure of DNA
• Hydrogen Bonds Between
Complementary Bases Hold the Two
DNA Molecules Together
• The Order of Nucleotides in DNA
Can Encode Vast Amounts of
Information
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DNA Replication: The Process
• The Replication of DNA Is a Critical Event
in a Cell’s Life
• DNA Replication Produces Two DNA Double
Helices, Each with One Old Strand and One
New Strand
– Basic features of DNA replication
– DNA replication
Copyright © 2005 Pearson Prentice Hall, Inc.
(F9.4 p. 155)
(F3 p. 158)
free nucleotides
DNA helicase
replication forks
DNA helicase
replication bubble
DNA polymerase #1
DNA
polymerase #2
DNA polymerase #1
continues along parental
DNA strand
DNA polymerase #2
leaves
DNA
polymerase #3
DNA polymerase #3
leaves
DNA
polymerase #4
DNA ligase joins
daughter DNA strands
DNA replication
DNA Replication: Accuracy
• Genetic Constancy During Cell Reproduction
• Proofreading: Produces Almost Error-Free
Replication of DNA
– 1 Replication Error/ 1,000 to 10,000 BP
– Proofreading => 1 Error/1,000,000 BP
• Mistakes Do Happen
– Produces Variability
– Natural Selection Can Only Act on Variants that Exist
– Essential for Evolution
• Good for Population, Even if Bad for Individual
– Human Vs. HIV
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