Download Section 11-1

QOD
How do your genes
determine your eye color?
Section 10-1
Discovery of DNA
DNA is The Genetic Material

Evidence in favor of DNA
• Frederick Griffith – 1928
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Transformation
• Avery, McCarty & MacLeod – 1944
• Hershey & Chase – 1952
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Bacteriophages
LE 16-2
Living S cells
(control)
Living R cells
(control)
Heat-killed
S cells (control)
Mixture of heat-killed
S cells and living
R cells
RESULTS
Mouse dies
Mouse healthy
Mouse healthy
Mouse dies
Living S cells
are found in
blood sample
Chapter 10
Section 1 Discovery of DNA
The HersheyChase
Experiment
QOD
a) Draw and label a
diagram of DNA.
b) How does your DNA
store genetic
information?
Section 10-2
DNA Structure
What is DNA?
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Deoxyribonucleic acid
Genetic information
Traits
Instructions/blue prints for proteins
DNA
Structure
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The Structural Model of DNA

Rosalind Franklin
(with Maurice
Wilkins)
• X-ray diffraction
• Sugar-phosphate
backbones on the
side

James Watson and
Francis Crick
• Double-helix
• Nitrogen bases facing
inward
Make-up of DNA
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Makeup of DNA

Nucleotides (3 parts)
• Deoxyribose
• Phosphate group
• Nitrogenous bases (4 different)
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Purines
• Adenine (A)
• Guanine (G)
Pyrimidines
• Cytosine (C)
• Thymine (T)
Chapter 10
Section 2 DNA Structure
DNA Nucleotides
Nucleotide Structure

Nucleotides join by bonding a
deoxyribose of one nucleotide to the
phosphate group of another
• Sugar and phosphate = backbone of
DNA
• Nitrogeneous base stick out to side

Chargaff’s rule
• Complementary bases
III. DNA Structure

Watson and Crick Model (1953)
• DNA is 2 strands
• Held together by weak hydrogen bonds
• H-bonds only form between certain
bases (complementary base pairs)
• Double-helix shape
Chapter 10
Section 2 DNA Structure
DNA Nucleotides
QOD
Why does DNA replicate
itself? When does DNA
replicate itself? How does
DNA replicate itself?
Section 10-3
DNA Replication
DNA
Replicating
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I. DNA Replication

Steps:
• 1) Strands separate


Replication fork
Helicases
• 2) Base pairing
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DNA polymerase
Complementary base pairing
• 3) Bonding of new nucleotides
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Covalent bonds
Semiconservative replication
Chapter 10
Section 3 DNA Replication
DNA Replication
DNA Replication
Chapter 10
Section 3 DNA Replication
Replication Forks Increase the
Speed of Replication
Results
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Results:
• Two identical strands of DNA
• Each has 1 original half and 1 new half
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Accuracy and Repair
• Proofreading
• Mutations
• Cancer
Gene Mutations
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Point mutations
• Substitution
• Frameshift mutations
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Insertion
Deletion
Gene Mutations
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QOD
Compare and Contrast
DNA to RNA.
Section 10-4
Protein Synthesis
Introduction
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Genes, made of DNA, control traits
DNA contains the information to
make proteins
The sequence of bases found in DNA
contains the instructions for
assembling a chain of amino acids
(polypeptide)
I. RNA
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Made of nucleotides, like DNA
Differences:
Types:
• mRNA
• tRNA
• rRNA
Chapter
10
RNA
Structure
and
Function
Section 4 Protein Synthesis
QOD
How is transcription similar
to DNA replication?
How is it different?
Transcription of DNA
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II. Transcription

Production of mRNA molecule
• Uses half of the DNA as a template
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First step in protein synthesis
Occurs in Nucleus
Chapter 10
Section 4 Protein Synthesis
Transcription
Steps of Transcription
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Separation of DNA
• Promoters
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Formation of complementary RNA
• One strand
• RNA polymerase
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RNA will detach and DNA reconnects
• Termination signal
Transcription
More on Transcription
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Promoters – regions of DNA that act
as signals to start/stop transcription
RNA editing:
• Introns
• Exons
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Final product: transcripts
• mRNA
Introduction
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Proteins = multiple chains of amino
acids
There are 20 different amino acids
Structure of proteins
• Primary
• Secondary
• Tertiary
• Quartenary
Fig. 2.17a
Fig. 2.17b
Fig. 2.17c
Fig. 2.17d
QOD
What is the next step in
protein synthesis?
How is the mRNA read?
The Genetic Code
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The mRNA is “read” by the ribosome
three bases at a time
Codon – 3 consecutive bases that
specify a single amino acid
• Example: UCGCACGGU
Proteins are made by “reading” and
“translating” these codons
Chapter 10
Section 4 Protein Synthesis
Genetic Code
Translation
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Translation is the decoding of the
mRNA molecule into a polypeptide
chain
Occurs at the ribosome
Involves mRNA, tRNA, rRNA
QOD
What is the result of a
mutation (point or
frameshift) in the
sequence if DNA?
Chapter 10
Section 4 Protein Synthesis
Translation: Assembling
Proteins
Steps of Translation
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mRNA moves to ribosome
Role of tRNA
• Each tRNA has an anticodon that is
complimentary to mRNA codon
• Each type of tRNA carries a specific
amino acid
• When the codon and anticodon match,
an amino acid is brought over to the
ribosome
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Codon:
AUG
Anticodon: UAC
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Two codons read by the ribosome at
the same time
When two amino acids are at the
ribosome, a peptide bond is formed
between them
1st tRNA is released and ribosome
moves to 3rd codon, where another
amino acid is brought over by tRNA
tRNA Anticodon
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tRNA Molecule-Amino Acid
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
Polypeptide continues to grow in this
manner until the ribosome reaches a
“stop” codon
• Codon that signals ribosome to stop
translation
• UGA, UAG, UAA
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Protein is then released
Polysomes – multiple ribosomes
Translation
Gene Mutations
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