Chapter 7
Molecular organisationMolecular organisationof chromosomes
OverviewIntroductionGenome sizeDNA supercoilingBacterial chromosomesEukaryotic chromosomesPolytene chromosomesPolytene chromosomesUnique and repetitive sequences in eukaryotesMolecular structure of the centromereMolecular structure of the centromereMolecura structure of the telomere
Introduction
Chrom. Prokaryotes EukaryotesNumbers Usually 1 Usually > 1Shape Usually Usually linearShape Usually
circularUsually linear
Location Free NucleusLocation Free NucleusExtra Plasmids Mitochondria
Chl l tChloroplasts
OverviewIntroductionGenome sizeDNA supercoilingBacterial chromosomesEukaryotic chromosomesPolytene chromosomesPolytene chromosomesUnique and repetitive sequences in eukaryotesMolecular structure of the centromereMolecular structure of the centromereMolecura structure of the telomere
Genome size and evolutionary ycomplexity: C-value paradox
Genome size and evolutionary ycomplexity: C-value paradox
Genome size and evolutionary ycomplexity: C-value paradox Overview
IntroductionGenome sizeDNA supercoilingBacterial chromosomesEukaryotic chromosomesPolytene chromosomesPolytene chromosomesUnique and repetitive sequences in eukaryotesMolecular structure of the centromereMolecular structure of the centromereMolecura structure of the telomere
The supercoiling of DNAp gDefinition
The supercoiling of DNAp gDefinition
The supercoiling of DNAp gTopoisomerase I
The supercoiling of DNAp gTopoisomerase II
OverviewIntroductionGenome sizeDNA supercoilingBacterial chromosomesEukaryotic chromosomesPolytene chromosomesPolytene chromosomesUnique and repetitive sequences in eukaryotesMolecular structure of the centromereMolecular structure of the centromereMolecura structure of the telomere
The structure of bacterial chromosomes
Packaging proteins:HU (wrapping) FIS & IHF (bending) HU (wrapping), FIS & IHF (bending), HNS (compaction)
NucleoidNucleoidIndependent, supercoiled loops
The structure of bacterial chromosomes Overview
IntroductionGenome sizeDNA supercoilingBacterial chromosomesEukaryotic chromosomesPolytene chromosomesPolytene chromosomesUnique and repetitive sequences in eukaryotesMolecular structure of the centromereMolecular structure of the centromereMolecura structure of the telomere
Eukaryotic chromosomesyPackaging feat
One extended chromosome = 35 Km long 1mm spaghettilong 1mm spaghettiTo organize in nucleus = boxTo organize in metaphase chromosome: 16 x 2 feet canoe
Eukaryotic chromosomesyChromatin & the nucleosome
Chromatin = DNA + proteins (histone + non-histone))Nucleosome
Core particle (145 bp + 2x Core particle (145 bp + 2x [H2A,H2B,H4,H4]+ linker DNA + H1
Histones:Rich in ARG and LYSRich in ARG and LYSHighly conservedModified histone NH2-tailsModified histone NH2-tails
Eukaryotic chromosomesyThe nucleosome
Eukaryotic chromosomesyThe nucleosome
Eukaryotic chromosomesyThe nucleosome
Eukaryotic chromosomesy30nm fiber
Eukaryotic chromosomesyChromosome territories
Eukaryotic chromosomesyCondensation at cell division
CondensinsCondensins
Eukaryotic chromosomesyCondensation at cell division
ChromosomeChromosomescaffold
OverviewIntroductionGenome sizeDNA supercoilingBacterial chromosomesEukaryotic chromosomesPolytene chromosomesPolytene chromosomesUnique and repetitive sequences in eukaryotesMolecular structure of the centromereMolecular structure of the centromereMolecura structure of the telomere
Giant polytene chromosomes OverviewIntroductionGenome sizeDNA supercoilingBacterial chromosomesEukaryotic chromosomesPolytene chromosomesPolytene chromosomesUnique and repetitive sequences in eukaryotesMolecular structure of the centromereMolecular structure of the centromereMolecura structure of the telomere
Unique & repetitive sequences q p qRenaturation kinetics
Unique & repetitive sequences q p qRenaturation kinetics
Highly repetitiveg y p
Middle repetitiveMiddle repetitive
Unique
Unique & repetitive sequencesq p qHighly repetitive sequences
Localized “satellite” repeats = heterochromatin
Unique & repetitive sequencesq p qHighly repetitive sequences
Interspersed repeats
Unique & repetitive sequencesq p qMiddle repetitive sequences
Less abundant transposonsPseudogenesPseudogenesGene familiesSegmental duplications
Unique & repetitive sequencesq p qUnique sequences
GenesRegulatory elementsRegulatory elements
OverviewIntroductionGenome sizeDNA supercoilingBacterial chromosomesEukaryotic chromosomesPolytene chromosomesPolytene chromosomesUnique and repetitive sequences in eukaryotesMolecular structure of the centromereMolecular structure of the centromereMolecura structure of the telomere
Molecular structure of the centromereMolecular structure of the centromereTypes
Holocentric chromosomes (f.i. C. elegans)elegans)Localized centromeres
P i (f i S i i )Point centromeres (f.i. S. cerevisiae)Regional centromeres (f.i. mammals)
Molecular structure of the centromereMolecular structure of the centromerePoint centromeres
Molecular structure of the centromereMolecular structure of the centromereRegional centromeres
OverviewIntroductionGenome sizeDNA supercoilingBacterial chromosomesEukaryotic chromosomesPolytene chromosomesPolytene chromosomesUnique and repetitive sequences in eukaryotesMolecular structure of the centromereMolecular structure of the centromereMolecular structure of the telomere
Molecular structure of the telomereMolecular structure of the telomereFunction of telomerase
Molecular structure of the telomereMolecular structure of the telomereFunction of telomerase
Molecular structure of the telomereMolecular structure of the telomereTelomerase
Molecular structure of the telomereMolecular structure of the telomereTelomeric DNA
Molecular structure of the telomereMolecular structure of the telomereG-quartet structure