2. INTRODUCTION
Nucleus is a prominent organelle in the cell .
Eukaryotic cell (well distinguished
morphology) and prokaryotic cell (nucleoid) .
Nucleus is control the
activity of cell .
Largest organelle in the cell .
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3. HISTORY
Nucleus ( latin ) is
discovered by
ROBERT BROWN
scottish botinsist in
1831 .
He told it plays key
role for fertilization
and embryo
development .
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4. POSITION OF NUCLEUS
Nucleus is present in center , eccentric postion because of
cell secritions accumulate inside the cell .
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SHAPE , SIZE .
It is round , oval , spherical ,
ellipsoidal or disc shaped .
Depending on the cell size of nucleus
is variable and it directly proportional
to cytoplasm .
Using
HEYWIG’S
formula
5. No of nucleus defination example
Mononucleate The cell contains
single nuclei
Amoeba
Binucleate The cell which
contains two nuclei _
1 . micronucleus
2 . macronucleus
Paramecium
Polynucleate The cell which
contain more than two
nuclei .
Animal (syncytial)
Plant (coenocyte)
Epidermal cell of
ascaris .
Osteoblast .
Vaucheria .
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NUMBER
6. ULTRA STRUCTURE OF
NUCLEUS
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Typical structure of nucleus
showing these components .
Nuclear envelope
Nuclear sap
Chromatin
Nucleolus
7. NUCLEAR ENVELOPE
(KARYOTHECA)
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This envelope is distinguish
nucleus responsible for
communication between
cytoplasm and nucleus the
phospholipid bilayer .
1 )outer membrane
2 )Inner membrane .
In between the membrane
perinuclear space (10 to 50 nm) is
present .
8. Outer membrane is continuous with rough
endoplasmic recticulum on that ribosome is present.
And to form the transport vesicle to golgi bodies .
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9. Inner membrane consist the thin filament (lamin
protein )its dense lined with it is called nuclear
lamina. Its on nucleoplasm . It gives mechanical
support to nuclear envelope and serve site for
attachment of chromatin fibers at nuclear periphery
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10. NUCLEAR PORE
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Nuclear pore act as
channel for
transporation between
cytoplasm and nucleus
.
It shows that sort of
cylindrical is called
annulus two distinct
annuli outer and inner
annuli .Made up to 8
to 9 granules ( diameter
100 to 250 Å ) .
11. Annuli arranged ring like structure and inbetween
the outer and inner ring on its side walls finger like
projection .
With in the pore centeral grannule is present with
a diameter of 40 to 300Å act as transporter .
Entire structure is called cart wheel .
Nuclear pore has basket like apparatus called the
nuclear pore complex .
This complex fills the pore like a stopper ,
projecting into both cytoplasm and nucleoplasm.
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12. FUNCTIONS OF NUCLEAR
ENVELOPE
Exchange of material : many substances have to
cross the nuclear envelope to reach the nucleus
from the cytoplasm and vice versa .
1) These substances are ions and small
molecules for example nucleotides , macromolecule
such as nucleoprotein and aggregates of
ribonucleoprotein particles 145 A◦ less than pore .
2) These passage is depends on their size .
3) There are two steps .BINDING,
TRANSLOCATION .
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13. BLEBBING : Nucleocytoplasmic exchange could be
directly through the nuclear bilayer by continuity of
endoplasmic reticulum .
Small sacs is developed by outpushing of nuclear
envelope on vesicle is formed is called blebbing .
It provides a sites for attachment for chromatin
fibres heterochromatin .
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14. NUCLEAR SAP (NUCLEOPLAMM)
It is a semifluid substance present in the nucleus .
It is bounded with nuclear envelope .
The nucleoplasm has a complex chemical
composition.
Nucleic acids : The most common nucleic acids of
the nucleoplasm are the DNA and RNA.
1) Both may occur in the macromolecular
state or in the form of their monomer nucleotides.
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15. PROTEIN
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HISTONE
Known as basic
It composed of
amino acid
arginine , histidine,
lysine .
NON HISTONE
Known as acidic
The most abundant
acidic proteins of
the euchromatin
are the
phosphoproteins.
16. ENZYME
Most of the nuclear enzymes are composed of non-
histone(acidic) proteins.
DNA polymerase , RNA polymerase,
NAD Synthetase , Nucleoside triphosphatase ,
Adenosine diaminase , Nucleoside phosphorylase ,
Guanase , Aldolase , Enolase ,
3-phosphoglyceraldehyde dehydrogenase, Pyruvate
kinase.
Co –enzyme ATP and ACETYL CoA.
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17. Helps the nucleus to keep its shape .
when the nucleus is subjected to a moderate high
temperature (37◦ c) the nuclear envelope get
solubilized , chromatin is solubilized with high salt
concentration ,and nucleic acid are digested by
nucleases ,the network fibrils is retaining the shape
of the nucleus remains .
This network fibrils is known as nuclear matrix . It
regulate transcription and replication of DNA.
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19. CHROMATIN
During the interphase nucleus found a number of fibrillar
structures that constitute a network called chromatin fibrillar or
chromonemata .
Such chromatin becomes thick ribbon like structure is called
chromosome .
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20. Chromatin is a tight complex formed between
eukaryotic DNA and nucler protein .
The key protein in chromatin involved in orderly
packing eukaryotic DNA are the basic protein
(histones) is positive charge and it bind to
negatively charged DNA .
There are five basic classes of histones molecule
known as H1, H2A, H2B, H3, H4 .
When interphase nucleus is observed under
electron microscope it appears like a BEADS ON
STRING .
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22. The DNA in a chromatin is very tightly associated with
histones that packages its repeating structural units called
nucleosome .on that 200bp .
Nucleosome – DNA – WEDGE SHAPED HISTONE
OCTOMER – linker DNA - nucleosome core particle .
Non histones chromosomal protein are also associated with
chromatin . But not take part in basic structure . Role in
regulation of expression of specific genes.
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23. EUCHROMATIN
light stained
Diffused region
High amount of RNA
Low amount of DNA
HETEROCHROMATIN
Dark stained
Condensed region
High amount of DNA
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24. NUCLEOLUS
Morphologically it appears spheroid shape .
Size can vary from 1to 5 micro meter .
Depends the species no . Of nucleolus .
Its is acidophilic .
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Male kangaroo – single
Female kangaroo-two
25. COMPONENTS
During the cell division on early it gets
disappear and later at the time of daughter
nuclei formation it will appear –pars
amorpha .
Permanent component does not
disappeear persistant thoughout the life
cycle . Its filamentous attach RNA –
nucleolonema .
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26. 26
ULTRASTRUCTURE
OF NUCLEOLUS
Granular portion being
made up of dense
granules arranged
peripherally and
measuring about 150-
200 A in diameter . It
consists of ribonuclei
protein .
27. 27
Fibrillar portion having the fibrils of 50-80A length
and composed of ribonucleoprotein. This region is
also known as nucleolonema. It generally occupies the
central region of the nucleolus .
The nucleolus has no limiting membrane and the
calcium ions are believed to maintain the intact
organization of the nucleolus .
28. NUCLEOLAR ORGANIZER (rDNA)
Heterochromatin region is found associate with
nucleolus to consitute nucleolar organizer .
The 18S, 5.8S and 28S RNAs are synthesized in the
nucleolus .
The nucleolar organizer is usually located in a
secondary constriction on the chromosome.
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29. FUNCTION OF NUCLEOLUS
HELPS TO SYNTHESIS OF RNA –
It help to synthesis to protein by the formation
of ribonucleic acid .
large amount of protein synthesis if it has high
RNA content so large nucleoli .
AS AN INTERMEDIATOR OF GENETIC
INFORMATION FROM GENERATION TO ANOTHER .
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