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DNA Structure and Replication 1
DNA Structure and Replication
Chapter 14 (Chromatin, oncogenes & TSG
in Chapter 10)
Topics you are not responsible for:Section 14.5: eukaryote replicationSection (p 268-269) on ‘replisomes’
End of Chapter questions:Understand: allApply: 1 – 6 & 8Synthesize: 1 & 3
Do all mQuiz questions
Do MolnQuiry Nucleic Acids Chapter
DNA Structure and Replication 2
History of the discovery of the genetic material - 1?
Bacteriophages infect Cells with DNA alone
Alfred Hershey Martha Chase experiments -- 1928
-- radiolabeled DNA and protein
HC-Experiment
DNA Structure and Replication 3
History of the discovery of the genetic material - 2?
P.A. Levene showed DNA isa polymer of nucleotides
Erwin Chargaff showed DNAcomposition differs among organisms
DNA Structure and Replication 4
What is the structure of a DNA strand?
Nucleotides
Phosphodiester linkages
Sugar-Phosphate Bone
3’ to 5’ orientation
DNA Structure and Replication 5
History of the discovery of the genetic material - 3?
J. Watson, F. Crick, R. Franklin and M. Wilkins
Determined the 3-D structure
What did Franklin and Wilkins contribute?
Crystalography
What did Watson and Crick Contribute?-- Double helix-- Antiparallel orientation-- Base pairing
DNA Structure and Replication 6
What is the structure of the DNA double helix?
Complimentary base pairing-- base pairs are hydrogen bonded
Antiparallel orientation
Major and minor grooves
Models
DNA Structure and Replication 7
How does DNA replicate -1?
Semiconservative replication
The M. Meselson and F Stahl experiment
MS-Experiment
DNA Structure and Replication 8
How does DNA replicate -2?
The need for RNA priming--”RNA Primase”
Adding nucleotides-- “DNA Polymerase”
5’ to 3’ orientation
Proofreading ability
NucleotidePolymerization
Proofreading
DNA Structure and Replication 9
How does DNA replicate -3?
Origins of Replication
Replication ‘forks’
HelicaseDNA gyrase
Replisomes
DNA Structure and Replication 10
How does DNA replicate - 4?
New strand 5 ‘ 3’ orientation
Leading & lagging strands
DNA HelicaseSS Binding proteinRNA PrimaseDNA Polymerase IIIDNA Polymerase ILigase
Time
DNA Replication
DNA Structure and Replication 11
What is the structure of eukaryotic chromatin?(from chapter 10; page 190)
Shape
Structure of chromatin
Nucleosomes
Functional areas
Centromeres
Telomeres
Replication
Supercoiling
Model
DNA Structure and Replication 12
Sickle-cell anemia mutation
What are mutations?-- see section chapter 20 section 20.2
Changes to the base sequence
Some examples
“Point Mutations”Base substitutionBase deletionBase chemical change
“Sequence mutations”DuplicationsDeletionsInversions
“Chromosomal aberrations”
DNA Structure and Replication 13
What types of chromosomal aberrations can occur?
DeletionsTranslocationsDuplications
-- aneuploidy-- polyploidy
Breakages
What is the role ofmutated tumor suppressor genes?
-- detection & repair of DNA-- cell cycle control-- triggering of apoptosis
Meningioma karyotypeLOH - #17
Aneuploidy - #s 9, 7, and 20Translocation/duplication - #s 2 and 6
DNA Structure and Replication 14
How is DNA damage repaired?
DNA polymerase “proofreading”
Mutation detection-- tumor suppressor genes
Excision repair (via endonuclease)
Other repair enzymesphotolyase thymine dimers
Excision Repair