The document provides information about the nucleus and its components. It discusses that the nucleus is a prominent organelle found in eukaryotic cells that controls cellular activity. It describes the various structures of the nucleus including the nuclear envelope, nucleolus, chromatin, and nuclear pores. The nuclear envelope forms the boundary of the nucleus and contains nuclear pores that regulate transport between the nucleus and cytoplasm. Chromatin and the nucleolus are also described along with their roles in packaging DNA and synthesizing RNA, respectively.

1. i
PRESENTED BY
K.SIVARAJ ,
shansiva1996@gmail.com
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NUCLEUS

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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18. NUCLEAR MATRIX
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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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21. 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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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 .

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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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30. QUESTIONS
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