The document summarizes key parts and functions of the nucleus. The nucleus contains nuclear membrane, nucleoplasm, chromatin, and nucleolus. It is surrounded by a double membrane nuclear envelope that contains pores allowing transport between the nucleus and cytoplasm. The nucleus controls all cell functions and carries hereditary material. It was discovered in 1831 and is present in all eukaryotic cells except mature red blood cells and phloem cells.

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.