Nucleus, the central part of the cell, a center for various reactions.

1. INTRODUCTION
• TOPIC : CELL NUCLEUS
• DEPARTMENT: ZOOLOGY
• UNIVERSITY OF PESHAWAR

2. TOPIC OVERVIEW
• HISTORY
• CHARACTERS
• SHAPEANDSIZE
• STRUCTURE
• FUNCTION

3. History
Robert Brown
1773-1858
-Discovered in 1831 by
Scottish botanist Robert Brown
-Suggested the nucleus played a
key role in fertilization and
development of the embryo in
plants
-Name (nucleus) derived from
the Latin word for kernel/nut

4. Main Characteristics
• Membrane-enclosed organelle
found in eukaryotic cells
• Generally found in the central
region of the cell (in animal
cells)
• Roughly spherically shaped
• Largest and most easily seen
organelle

5. SHAPE AND SIZE
• SPERICAL OR OVAL SHAPE ;
• PARAMISIUM HAVE BEAN SHAPE ,
• SMOTH MUSCLES HAVE ELONGTED
• LOCATED AT THE CENTRE OF CELL
• EXIST IN VERITY OF SHAPES AND SIZES
• DEPEND ON CELL SIZE

6. STRUCTURE
• CONSIST OF :
• NUCLEAUR MEMBRANCES
. NUCLEUR PORES
• NUCLEOPLASM
• NUCLEOLUS
• CHROMATIN
.CHROMOSOME
.DNA
.PROTEIN

7. Structure

8. NUCLEAR MEMBRANE
• DOUBLE LAYERED COVERING OF NUCLEUS
• SPACE BETWEEN MEMBRANE IS
PERINUCLEUR SPACE (LIPOPROTEIN)
• MAINTAIN SHAPE OF NUCLEUS

9. Nuclear Envelope
Consists of:
• Phospholipid bi-
layer membrane
• Nuclear Pores
• Ribosomes

10. Nuclear Pores
• Allow small molecules to diffuse
easily between nucleoplasm &
cytoplasm
• Control passage of proteins & RNA
protein complexes
– Import: proteins moving in to be
incorporated into nuclear structure
or to catalyze nuclear activities
– Export: RNA / RNA-protein
complexes to the cytoplasm

11. Nucleoplasm
A jelly-like (made mostly of water) matrix
within the nucleus
All the other materials “float” inside
Also term as “karyolamp”
Helps the nucleus keep its shape and serves
as the median for the transportation of
important molecules within the nucleus

12. Nucleolus
• Largest structure present inside the
boundaries of the nucleus
• Dark staining zone in center of nucleus
• Where intensive synthesis of ribosomal RNA
takes place
• Main components are ribonucleic acid (RNA),
deoxyribonucleic acid (DNA) and proteins

13. CHROMATIN
• THIN THREAD LIKE STRUCTURE EMBEDED IN
NUCLEOPLASM CONSISTS OF:
• DNA
• RNA
• HISTONE AND NON HISTONE PROTEIN
• HISTONE ARE BASIC PROTEIN PACKED DNA
TO STRUCTURAL UNIT
• IT CONDENSE TO FORM CHROMOSOME

14. Chromatin &
Chromosomes
Chromosomes contain DNA in a condensed form
attached to a histone protein.
Chromatin is comprised of DNA. There are two types
based on function.
Heterochromatin: highly condensed,
transcriptionally inactive mostly located
adjacent to the nuclear membrane
Eurochromatin: delicate, less condensed
organization of chromatin, located in a
transcribing cell
* Transcribing means equivalent RNA copies are being made from the DNA to create proteins.

15. DNA
DNA, or deoxyribonucleic acid, contains
the information needed for the creation
of proteins (which include enzymes and
hormones) and is stored in the nucleus,
as already said, in the form of chromatin
or chromosomes.
The nucleus is the site of DNA
duplication, which is needed for cell
division (mitosis) and organism
reproduction and growth.

16. Proteins and Cell Regulation
The nucleus oversees cells’ functions and
regulatory mechanisms for keeping the cell
healthy and alive.
The nucleus controls growth of the cell through
the synthesis of structural proteins, energy and
nutrient metabolism.
The nucleus regulates the secretion of ribosomes,
which are made in the nucleolus and are the sites
of gene transcription.

17. Primary Functions within the Cell
• Repository of genetic information (DNA & RNA)
• Enables the synthesis of nearly all proteins
• Houses the nucleolus
• Responsible for production of ribosomes
• Selective transportation of regulatory factors and
energy molecules through nuclear pores

18. Functions
The nucleus is often compared to the
“command center,” as it controls all
functions of the cell.
It is important in regulating the actions of
the cells.
It plays an important part in creating the
cell’s proteins.
It is involved in important processes
dealing with DNA and other genetic
molecules.

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