TOPIC: ARCHITECTURE OF CHROMOSOME IN PROKARYOTES AND

EUKARYOTES

WELCOME TO CLASS PRESENTATION OF

CYTOGENETICS

PRESNTED BY:- VIPIN PANDEY

S. NO PROKARYOTS S.NO EUKARYOTS

1 These are primitive organism like bacteria, virus, & BGA.

1 These are higher organism other than bacteria, viruses, & BGA .

2 They do not have well defined nucleus and nuclear membrane.

2 They have well defined nucleus surrounded by a nuclear membrane.

3 The DNA is free of structural proteins. 3 The DNA is tightly associated with specific proteins.

4 Prokaryote cell has DNA plus ribosomes.

4 Eukaryote cell has nucleus and various cell organelles.

5 Nucleus is absent. 5 Nucleus is present.

WHAT DIFFERENCE IN PROKARYOTES & EUKARYOTS CELLS

∗ The darkly stained, rod shaped bodies visible under light microscope in a cell during metaphase stage of mitosis are called chromosome.

CHROMOSOME

WHEAR IS FOUND CHROMOSOME?∗ Chromosome is found of all cells .

WHAT IS CHROMOSOME ?

Discovered by :- Strasburger, 1875; Coined term by :- Waldeyer, 1888

CHROMOSOME

WHEAR IS FOUND CHROMOSOME IN CELLS ?

∗ Chromosome is found of all cells in the nucleus.

Discovered by :- Strasburger, 1875; Coined term by :- Waldeyer, 1888

∗ DNA is very long.

WHY GENES/DNA ARE PACKEDED ON FORM OF CHROMOSOME ?

CHROMOSOME

~13.6cm.

~22cm.

~5.44m.WHEAT 3 TYPES GENOMIC DNA IS, PACKED IN 21 CHROMOSOMES

RICE GENOMIC DNA AREPACKED IN 12 CHROMOSOME

SORGHUM GENOMICDNA AREPACKED IN 10 CHROMOSOME

∗ Naked DNA is unstable in nucleus or cytoplasm . ∗ Time of cell division chromosome easily distribute

parental to daughter cells by the centromere. ∗ Easily regulation of gene action.

WHY GENES/DNA ARE PACKEDED ON FORM OF CHROMOSOME ?

CHROMOSOME

∗Precise distribution of DNA parental to daughter cells. In Somatic cell 2n to 2n;

CHROMOSOME

∗Precise distribution of DNA parental to daughter cells. In Gametic cell 2n to n.

CHROMOSOME

2n

n

n

n

n

∗ Prokaryotic chromosome is consists of single circular, double-stranded DNA molecule.

∗ It has no histone protein.∗ Chromosomes are stored in nucleoid in which DNA in

binding to some proteins.∗ The genome of prokaryotes is often significantly

larger than the cell it self. How it is possible?∗ Contain only one copy of the gene (hapolid).

Prokaryotic chromosome

∗ Non essential genes are stored outside of chromosome in plasmid.

∗ It is circular molecule of DNA but the total length of DNA molecule is very large 1100µ.

Nucleoids of prokaryotes'

AGCTAGCTAGCTAGCTAGCTAGCTAGCTAG

TCGATCGATCGATCGATCGATCGATCGATC

1100µ

∗Diameter of fully expanded E.coli circular DNA is 350µ, while an E.coli cell has the diameter of only 2-5µ.∗In chromosome have 40-50 loops or domains found, which are connected or binding with RNA or proteins. ∗Loops are coiled and, coiled loops are called super coiled loops; it is attached with central scaffold protein

Nucleoids of prokaryotes'

5µ

∗ In the bacteria other than a big chromosome 1-20 covalently closed circular DNA molecules structure which includes genetic information & presenting in cytoplasm are called plasmids.

∗ It have stored non essential genes.∗ It have capable of replication.

Plasmid

∗ Under light microscope each chromosome consists of several parts like-

∗ Centromere / primary constriction.∗ Chromatids.∗ Secondary constriction & satellite.∗ Telomere.∗ Chromomere.∗ Chromonema.∗ Matrix.

Eukaryotic chromosome

∗ Centromere / primary constriction.∗ Chromatids.

Eukaryotic chromosome

∗ Chromomere.∗ Chromonema.

Eukaryotic chromosome

Chromosome packagingNucleosome solenoid model

∗ Artificial chromosome refers to synthetic chromosome consisting of fragments of DNA integrated into a host chromosome.

∗ It is two type-∗ YAC-Yeast Artificial chromosome∗ BAC-Bacterial Artificial Chromosome

Artificial chromosome

YAC-Yeast Artificial chromosome

∗Yeast artificial chromosome.∗Self-replicating elements.∗Can insert segments up to 1000-2000 kb pairs.

∗Can replicate any inserted DNA via transfer to yeast cells.

∗ Tel – telomeres.∗ Cen – centromere.∗ Ori - Origin of replication.∗ Selectable markers.∗ Restriction enzyme recognition sites.

Essential elements for YACs

YAC-Yeast Artificial chromosome

∗ BAC is cloning vector system in E.coli developed by Mel Simon and his colleagues.

∗ It is developed to alternative of YAC vectors.∗ BAC is maintained in E.coli as large single

copy plasmids that contain inserts of 150-350kbp.

BAC-Bacterial Artificial Chromosome

BAC-Bacterial Artificial Chromosome

∗ It is used to map genes in genomes.∗ It is also useful in testing f function of genes. ∗ It is used to make transgenic plants. ∗ It is used for study of proteins structure.∗ It is used to desired gene cloning.

Uses of artificial chromosome

∗ Chromosomes, which differ significantly from normal chromosomes.

∗ It is differ from normal chromosome to either morphology or function.

∗ It is three types:-1.Lampbrush chromosome 2.Polytene chromosome or giant chromosome 3.B chromosome

Special types of chromosome

∗ Lampbrush chromosome are have large number of loops.∗ Loops giving a lampbrush appearance.∗ They are found in oocyte nuclei of both vertebrates &

invertebrates.

1.Lampbrush chromosome

∗ The multiple replicates of the same chromosome holding together in a parallel fashion resulting in very thick chromosome are known polytene chromosome.

∗ Found in certain tissues e.g., salivary glands of larvae, gut epithelium, Malphigian tubules and some fat bodies, of some Diptera (Drosophila, Sciara, Rhyncosciara)

∗ Giant chromosomes are made up of several dark staining regions called “bands”.

∗ It can be separated by relatively light or non-staining “interband” regions

2.Polytene chromosome or giant chromosome

Thank you