The document discusses the discovery and components of the cell nucleus. It describes how Robert Brown first observed nuclei in plant cells and how others later established that cells only come from pre-existing cells. The main components of the nucleus are then outlined, including the nuclear envelope, nucleoplasm, nuclear pores, nuclear lamina, chromosomes, and nucleolus. The nuclear envelope forms a double membrane barrier with nuclear pores that regulate transport. The nuclear lamina provides structural support and anchors other structures. The nucleolus is responsible for producing ribosomes.

1. Deepak yadav
m.sc-iii
Guided by:-prf.G K SRIVASTAVA University of allahabad

2. DISCOVERY
OF
NUCLEUS

3. Oldest known depiction of cells and
their nuclei by Antonie van
Leeuwenhoek, 1719.

5.  Robert Brown
- introduced the word areola or
nucleus, in the cells of the flower's outer
layer.
 Matthias Schleiden
-name "Cytoblast" (cell builder).

6. Robert Remak and Rudolf Virchow
propagated the new paradigm that cells
are generated solely by cells ("Omnis
cellula e cellula").
The function of the nucleus clear only
later, after mitosis discovered and the
Mendelian rules 20th century).

7. CELL
NUCLEUS

8. CELL NUCLEUS
• Latin nucleus or
nuculeus,
meaning kernel.
• The control center of the
cell.
• It contains most of the
cell's genetic material.

9. PRIMARY FUNCTIONS:
• Repository of genetic information
• Enables synthesis of nearly all proteins
• Houses the nucleolus
• Responsible for production of
ribosomes.
• Selective transportation of regulatory
factors and energy.

10. COMPOSITION

11. NUCLEAR ENVELOPE
 separates the cell's genetic material from
surrounding cytoplasm.
 serve as a barrier between nucleoplasm
and the cytoplasm.

12. Also known as the nuclear membrane, nucleolemma, or karyotheca.
is the double lipid bilayer membrane which surrounds the genetic material and nucleolus in
eukaryotic cells.

13. 2 lipid bilayer membranes:
•Punctured  nuclear pores  connect the two membranes.
•Different in protein composition
•Separated by perinuclear space
Inner membrane – associated with nuclear lamina
Outer membrane – continuous with endoplasmic reticulum

15. Outer membrane
The outer nuclear membrane is also contiguous with the
endoplasmic reticulum.
While it is physically linked, the outer nuclear membrane
contains various proteins found in far higher concentrations than the endoplasmic
reticulum.
Inner Membrane
The inner nuclear membrane encloses the nucleoplasm, and is covered
by the nuclear lamina,
It is connected to the outer membrane by nuclear
pores which penetrate the membranes.

16. NUCLEOPLASM
 made up of water and other
dissolved substances.
 act as a suspension for organelles
 maintains the shape of the nucleus.

17. NUCLEAR PORE
 composed of multiple proteins
 allows the passage of molecules
from inappropriate entering or
exiting the nucleus.

18. •Large compared to other proteins.
•Octagonal symmetry.
•Mass approx. 125 megaDaltons in vertebrates.
•Cytoplasmic fibrils (tentacle-like)
•Nuclear meshwork

21. NUCLEAR PORES
The nuclear membrane is punctured by
thousands of nuclear pore complexes
They link the inner and outer nuclear membranes.

22. Function of the nuclear pore
Passive diffusion of low molecular weight solutes
Regulated transport of macromolecules larger than 40 kDa
Nuclear import signal: NLS
Nuclear export sequence: NES
Importins: cytoplasm to nucleoplasm
Exportins: nucleoplasm to cytoplasm
GTPase Ran controls interactions of cargo and karyopherin

24. NUCLEAR LAMINA
• structural support for the nuclear
envelope
• anchoring sites for chromosomes
and nuclear pores.

25. •Intermediate filaments & membrane associated proteins
(Lamins & nuclear lamin-associated membrane proteins)
•Lamin types: A, B1, B2, & C
•Mechanical support
•Regulates cellular events

26. PROGERIA
• Defective Lamina
protein makes the
nucleus unstable. That
nuclear instability
appears to lead to the
process of premature
aging in Progeria.

27. CHROMOSOMES
 Multiple linear DNA molecules.
 During most of the cell cycle
these are organized into chromatin
 During cell division the chromatin can
be seen to form the well-defined
chromosomes.

28. NUCLEOLUS
 synthesize rRna and assemble
ribosomes.

29. HAVE
YOU LEARNED?

30. Which of the following parts of
nucleus is responsible for the
formation of the ribosomes?
nucleoplasm
nucleolus
nuclear
envelope
chromosomes
A
B nucleolus
C
D

31. In the nucleus of eukaryotic cells, the genetic
material is complexed with protein and
organized into linear structures called:
A centrioles
chromosomes
histones plasmids
B
C D

32. Provide structural support for the nuclear
envelope and anchoring sites for
chromosomes and nuclear pores.
A Nucleoplasm
C
Cytosol
Nuclear Lamina
B
D
Nuclear
Membrane

33. The space between the
membranes is called:
perinuclear
space
internuclear
space
nuclear space
none of these
A
B
C
D
perinuclear
space

34. It prevents larger molecules, such as
nucleic acids and larger proteins, from
inappropriately entering or exiting the
nucleus.
nuleolus
nuclear
envelope
nuclear lamina
A
B
C
D nuclear pores

35. It serves as a barrier that prevent
macromolecules from diffusing freely
between the nucleoplasm and cytoplasm.
nuleolus
nuclear
envelope
nuclear lamina
nuclear pores
A
B
C
D