Presentation on Nucleus

1. NUCLEUS
Guided by :
Dr .Kaushik Kumar Panighrahi
Presented by :
Kanchan Kumari
Bsc . Ag 2nd year
Adm no. 04 C /15

2. INTRODUCTION
 Nucleus is the most important component of the cell
& it controls all the functional activities of the cell.
 The nucleus is present in all eukaryotic cells .Certain
mature cells,however ,do not have a nucleus .
e.g. Mammalian red blood corpuscles ,food
conducting phloem cell ,called sieve tube.
 The nucleus is the primary carrier of the hereditary
material.
 It was discovered by botanist Robert Brown in 1831.

3. PARTS OF NUCLEUS
 Nuclear membrane
 Nucleoplasm
 Chromatin
 Nucleolus

5. NUCLEAR MEMBRANE
 Nucleus is separated from surrounding cytoplasm by
a nuclear envelope which is double layer,
semipermeable .
 Perinuclear space is found between outer & inner
nuclear membranes .The outer membrane is
connected with endoplasmic reticulum.
 Its outer surface may contain ribosomes while inner
surface is smooth.
 The nuclear membrane contains a large no. of pores
which may be circular or polygonal having a
diameter of about 40-100mm

6.  Nucleus communicates with cytoplasm through
nuclear pores .
 Cellular structures which always disappears during
mitosis or meiosis is nuclear envelope.

7. NUCLEOPLASM
 The nucleus contains a viscous fluid the
nucleoplasm which keeps nucleus turgid.
 Nuclear sap contains enzymes of nucleic acid
synthesis like DNA or RNA polymerases , metal ions
histone & non histone protein.
 Underlying the inner nuclear membrane is the
nuclear lamina,a fibrous meshwork that
provides,structural support to the nucleus.
 The nuclear lamina is thought to serve as a site of
chromatin attachment.

8. CHROMATIN
 The term chromatin means colured material
indicate the ability of this material to easy take up of
stain for microscopic examination.
 The chromatin occurs in a non-dividing nucleus as
fine filaments .
 The major proteins of chromatin are the histones
which is a small proteins containing high proportion
of basic amino acids arginine and lysine that
facilitate binding with negatively charged DNA
molecule.

9. NUCLEOLUS
 Nucleolus was discovered by Fontana in 1781 and the
term nucleolus was coined by Bowman in 1840 .
 It is characterised by the absence of limiting
membrane ,presence of chromatin and granules and
fibrils of RNA and protein.
 Nucleolus consists of DNA , RNA, and protein. The
configuration of nucleolus is mainted by calcium.
 Nucleolus disorganises itself during late prophase
and reappear during telophase.