Organisation of the genetic material in pro- and eukariotic cellsDNA, chromatin, chromosomes

1 m = 2 Megadalton (2 x 106 Dalton) = 3 kbp

Genome ContentHuman Genome3200 MbSINE: 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

RelaxedSupercoiledTopoisomerases

Nucleus of a eukariotic cells (electronmicrograph)Function: protection, transport,gene expression

nuclear laminaHETEROCHROMATINeuchromatinheterochromatinnucleolus

1 m = 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 necessaryThe sructure of the 30 nmchromatin fiber is variable(heterogen)

11 and 30 nm chromatin fibers (electonmicrograph)beads-on-a-string structuresolenoid

H2AH2BH3H4

Chromatin structure and gene expresson in that area are hang on the chemical modification of histones (acetylations, metylation, phosphorylation)

A hiszton kd hipotzis

Condensins organise the loop-structureSMC = Structural Maintenance of Chromosomes family protein (part of the condensin complex)

DNAChromatinLoopsMetaphase chromosome

Chemical modification of the DNA (methylation) has role in regulation

de novo metylasesImprinting

XIST = X inactivaton specific transcriptXIC = X inactivation centerHistones 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

armssisterchromatidesKinetochor microtubuls

Lewin: Genes IX. Fig. 28.30

Telomer and telomerase

fibrillargranularlight stained

A magvacskafunkcii

Special chromosomesPoliten chromosome in salivary glands of Drosophila melanogaster Lampbrush chromosomes amphybian oocytes

Politenchromosomes

RNA synthesis on the politenchromosomes

Lampbrush chromosomes in an amphybian oocyte