introduction to dna structure
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mRNA
Transcription
Introduction
The Central Dogma of Molecular Biology
Cell
Polypeptide(protein)
TranslationRibosome
Reverse tanscription DNA
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DNA STRUCTUREchemical structure of the 4 nucleotides in DNA
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DNA STRUCTURE hydrogen bonded nucleotides
on opposite helices
DNA helices are antiparallel
carbons on sugar define ends... 5' and 3'
pyrimidines bond with purines T A C G
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DNA STRUCTURE bonding is specific: pyrimidines bond with purines implication: means for accurate replication
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DNA STRUCTURE helical structure of DNA
major & minor groves
10Å radius & 20Å diameter
3.4Å between nucleotide base pairs
34Å / 360° turn
10 nucleotide base pairs / 360° turn
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A TT AG CC
G
G C
TA
T
AG
C
C G
G C
T A
A T
Packaging DNA
Histone proteins
Histoneoctomer
B DNA Helix 2 nm
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A TT AG CC
G
G C
TA
T
AG
C
C G
G C
T A
A T
Packaging DNA
Histone proteins
B DNA Helix
Histoneoctomer
2 nm
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A TT AG CC
G
G C
TA
T
AG
C
C G
G C
T A
A T
Packaging DNA
Histone proteins
Histoneoctomer
Nucleosome
11 nm
B DNA Helix 2 nm
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Packaging DNA
A TT AC G
C G
G C
T A
A T
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Packaging DNA
A TT AC G
C G
G C
T A
A T
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Packaging DNA
A TT AC G
C G
G C
T A
A T
Protein scaffold
11 nm“Beads on a string”
30 nm
Tight helical fiber
Looped Domains200 nm
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Packaging DNA
G
C
A
T
Protein scaffold
Metaphase Chromosome
700 nm
11 nm
30 nm200 nm
2 nm
Looped Domains
Nucleosomes
B DNA Helix
Tight helical fiber
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Replication
Chromosomes, Chromatids and Centromeres
Centromere
Chromosome arm
Chromosome arm
Identicalchromatid
Chromatid
Anaphase
A packaged chromosome
Two identical chromosomes
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Chromosome Morphology
Chromosome arm
Chromosome arm
Centromere
Submetacentric Acrocentric TelocentricMetacentric
q arm
p armpetite
Chromosomes can be distinguished on the basis of size and the relative location of centromeres.
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Human karyotype (of a man with a normal 46,XY constitution)