organisation of the genetic material in pro- and eukariotic cells dna, chromatin, chromosomes
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Organisation of the genetic material in pro- and eukariotic cells
DNA, chromatin, chromosomes
1 µm = 2 Megadalton (2 x 106 Dalton) = 3 kbp
Genome ContentGenome Content
Human Genome3200 Mb
Genes and gene-related sequences 1200Mb
Intergenic DNA2000 Mb
Genes48 Mb
Related seq.1152 Mb
PseudogenesGene fragmentsIntrons, UTRs
Interspersed repeats1400 Mb
Other intergenic
regions600 Mb
Microsatellites90 Mb
Various510 Mb
LINES640 Mb
SINES420 Mb
LTR elements250 Mb
DNA transposons90 Mb
SINE: Alu, 281 bp, 300.000 p, 9%
LINE: L1, 6500 bp, 50.000 p, 7%, retrotransposon
T phage ofEsherichia coli~ 50 m DNA.
Single Circular DNA molecule of Escherichia coli, ~1,4 mm long
~4 cm linear DNA molecule contains in a usual human chromosome
E. coli: 4 639 221 nukleotide pairs, 4200 genes
Relaxed
Supercoiled
Topoisomerases
Nucleus of a eukariotic cells (electronmicrograph)Function: protection, transport,gene expression
nuclear lamina
HETEROCHROMATIN
euchromatin
heterochromatin
nucleolus
1 µm = 2 Megadalton (2 x 106 Dalton) = 3 kbp
Types of the chromatin: eu- and
heterochromatin
Structure of the chromatin ;
histons, nucleosomes, solenoid and loops
Histones:
small, basic, higly conserved proteins
30 nm chromatin fiber:interactions and modifications of site chains of histones and H1 histon are necessary
The sructure of the 30 nmchromatin fiber is variable(heterogen)
11 and 30 nm chromatin fibers (electonmicrograph)
„beads-on-a-string” structure
solenoid
H2AH2BH3H4
• Chromatin structure and gene expresson in that area are hang on the chemical modification of histones (acetylations, metylation, phosphorylation)
Condensins organise the loop-structure
SMC = Structural Maintenance of Chromosomes family protein (part of the condensin complex)
DNA
Chromatin
Loops
Metaphase chromosome
Chemical modification of the DNA (methylation) has role in regulation
de novo metylases
Imprinting
XIST = X inactivaton specific transcript
XIC = X inactivation center
Histones also play role in the inactivation
Localization of the chromosome 18 and chr. 19 in interphase nucleus
The chromosome structure and the cell divisionArms, centromer, telomers
arms sisterchromatides
Kinetochor microtubuls
Lewin: Genes IX. Fig. 28.30
Telomer and telomerase
fibrillar
granular
light stained
A magvacskafunkciói
Special chromosomes
Politen chromosome – in salivary
glands of Drosophila
melanogaster
Lampbrush chromosomes –
amphybian
oocytes
Politenchromosomes
RNA synthesis on the politenchromosomes
Lampbrush chromosomes in an amphybian oocyte