The nucleus is a membrane-bound organelle that controls all cell activity. It contains the cell's genetic material in the form of DNA and is the site of DNA replication and transcription. The nucleus is enclosed by a nuclear envelope containing nuclear pores that regulate movement of molecules between the nucleus and cytoplasm. Chromatin in the nucleus packages DNA and participates in gene expression. The nucleolus forms within the nucleus and produces ribosomes.
Presentation include Nucleus and its components like nuclear envelope, nucleolus, chromatin fibers, ultra structure of nucleus and its general functions.
Presentation include Nucleus and its components like nuclear envelope, nucleolus, chromatin fibers, ultra structure of nucleus and its general functions.
Discovery of nucleus
Evolution of nucleus
Structure of nucleus
Function of nucleus
Diseases related with nucleus
The nucleus was the first organelle to be discovered.
The probably oldest preserved drawing dates back to the early microscopist Antonie van Leeuwenhoek (1632 – 1723). He observed a "Lumen", the nucleus, in the red blood cells of salmon.
The nucleus was also described in 1831 by Scottish botanist Robert Brown.
Brown was studying orchids under microscope when he observed an opaque area, which he called the areola or nucleus, in the cells of the flower's outer layer. He did not suggest a potential function.
The cell nucleus is a membrane bound structure that:-
Contains the cell's hereditary information
Controls the cell's growth and reproduction
Direct the other components of cell through protein regulation
Make Proteins through central dogma of cell
DNA mRNA Protein
Emery-Dreifuss muscular dystrophy
Mutations in nuclear lamins associated with Emery-Dreifuss muscular dystrophy.
Emery-Dreifuss muscular dystrophy (EDMD) is a neuromuscular degenerative condition with an associated dilated cardiomyopathy and cardiac conduction defect.
It can be inherited in either an X-linked or autosomal manner by mutations in the nuclear proteins emerin and lamin A/C, respectively.
Traditionally muscular dystrophies were associated with defects in sarcolemma-associated proteins and, therefore, a nuclear connection suggested the existence of novel signalling pathways associated with this group of diseases.
Subsequently, other mutations in the lamin A/C gene were attributed to a range of tissue-specific degenerative conditions, collectively known as the 'laminopathies’.
Nucleus: Structure and function
nuclear membrane
nuclear lamins
Nuclear pore complexe
nuclear matrix, composition and its role
cajal bodies
SFCs
nuclear speckles
PML bodies
Nucleolus
Discovery of nucleus
Evolution of nucleus
Structure of nucleus
Function of nucleus
Diseases related with nucleus
The nucleus was the first organelle to be discovered.
The probably oldest preserved drawing dates back to the early microscopist Antonie van Leeuwenhoek (1632 – 1723). He observed a "Lumen", the nucleus, in the red blood cells of salmon.
The nucleus was also described in 1831 by Scottish botanist Robert Brown.
Brown was studying orchids under microscope when he observed an opaque area, which he called the areola or nucleus, in the cells of the flower's outer layer. He did not suggest a potential function.
The cell nucleus is a membrane bound structure that:-
Contains the cell's hereditary information
Controls the cell's growth and reproduction
Direct the other components of cell through protein regulation
Make Proteins through central dogma of cell
DNA mRNA Protein
Emery-Dreifuss muscular dystrophy
Mutations in nuclear lamins associated with Emery-Dreifuss muscular dystrophy.
Emery-Dreifuss muscular dystrophy (EDMD) is a neuromuscular degenerative condition with an associated dilated cardiomyopathy and cardiac conduction defect.
It can be inherited in either an X-linked or autosomal manner by mutations in the nuclear proteins emerin and lamin A/C, respectively.
Traditionally muscular dystrophies were associated with defects in sarcolemma-associated proteins and, therefore, a nuclear connection suggested the existence of novel signalling pathways associated with this group of diseases.
Subsequently, other mutations in the lamin A/C gene were attributed to a range of tissue-specific degenerative conditions, collectively known as the 'laminopathies’.
Nucleus: Structure and function
nuclear membrane
nuclear lamins
Nuclear pore complexe
nuclear matrix, composition and its role
cajal bodies
SFCs
nuclear speckles
PML bodies
Nucleolus
There are different components in the nucleus. A thin but distinct covering called the nuclear envelop, also known as the karyotheca, defines its perimeter. The solutes of the nucleus are dissolved in a clear fluid substance inside the envelope known as nucleoplasm, nuclear sap, or karyolymph.
The nuclear matrix, a network of protein-containing fibrils, the chromatin, which is made up of finely entwined nucleoprotein filaments, and one or more spherical structures known as nucleoli are all suspended in the nucleoplasm (singular, nucleolus). The nucleus is devoid of microtubules and membranes.
However, the nuclei of protozoans that form a mitotic spindle within the nuclear envelop contain microtubules. The nucleus is made up of 9–12% DNA, 5% RNA, 3% lipids, 15% simple basic proteins like histone or protamines, and 65% complex acid or neutral proteins. It also contains organic phosphates, inorganic salts or ions like Mg++, Ca++, and Fe++, as well as polymerases for the synthesis of DNA and RNA.
Functions
The nucleus serves as the cell's administrative hub. It performs the following primary purposes: By controlling the production of structural proteins, it keeps the cell alive. By directing the synthesis of enzymatic proteins, it controls cell metabolism. In addition to information about structure and metabolism, it also contains genetic material for the organism's behaviour, development, and reproduction. When necessary, it causes cell replication. It is where ribosome subunit formation takes place. By keeping only a select few genes active, it causes cell differentiation. It produces genetic changes that lead to evolution. The nuclear envelop separates the cytoplasm from the nucleoplasm. It is made up of an outer and an inner unit membrane. Each unit membrane is a trilaminar lipoprotein, similar to the plasma membrane, and is about 75Å thick. The inter membrane or perinuclear space, which divides the two unit membranes, is present between them. Its width is about 250Å. Ribosomes and polysomes are found in abundance on the outer, or cytoplasmic, surface of the outer membrane, which is also rough. These ribosomes continue to produce proteins. RER and the outer membrane occasionally blend together. As a result, the channels of the RER are continuous with the perinuclear space. Ribosomes are absent from the inner membrane of the nuclear envelope, but it has a thick layer called the nuclear lamina that is closely connected to its inner or nucleoplasmic surface.
The nuclear lamina is a network of filaments that ranges in thickness from 30 to 100 nm and is made up of lamin A, B, and C proteins. The inner membrane is supported and given shape by the nuclear lamina. The majority of the chromosomes are kept outside the nucleus by this connection between chromatin and the inner membrane. During mitosis, it also affects how the nuclear envelope degrades and then reforms. Nuclear Pores: The nuclear pores, which regulate the passage of some molecules and parti
DNA
its Discovery
Who Discovered DNA?
Credit for who first identified DNA is often mistakenly given to James Watson and Francis Crick, who just furthered Miescher’s discovery with their own groundbreaking research nearly 100 years later. Watson and Crick contributed largely to our understanding of DNA in terms of genetic inheritance, but much like Miescher, long before their work, others also made great advancements in and contributions to the field.
In 1866, before many significant discoveries and findings, Gregor Mendel was the first to suggest that characteristics are passed down from generation to generation. Mendel coined the terms as recessive and dominant.
In 1869, Friedrich Miescher identified the “nuclein” by isolating a molecule from a cell nucleus that would later become known as DNA.
In 1881, Nobel Prize winner and German biochemist Albrecht Kossel, who is credited with naming DNA, identified nuclein as a nucleic acid. He also isolated those five nitrogen bases that are now considered to be the basic building blocks of DNA and RNA: adenine (A), cytosine (C), guanine (G), thymine (T) and uracil (U) in case of RNA).
In 1882, Walther Fleming devoted research and time to cytology, which is the study of chromosomes. He discovered mitosis in 1882 when he was the first biologist to execute a wholly systematic study of the division of chromosomes. His observations that chromosomes double is significant to the later discovered theory of inheritance.
In Early 1900s, Theodor Boveri and Walter Sutton were independently working on what’s now known as the Boveri-Sutton chromosome theory, or the chromosomal theory of inheritance. Their findings are fundamental in our understanding of how chromosomes carry genetic material and pass it down from one generation to the next.
In 1902, Mendel’s theories were finally associated with a human disease by Sir Archibald Edward Garrod, who published the first findings from a study on recessive inheritance in human beings in 1902. Garrod opened the door for our understanding of genetic disorders resulting from errors in chemical pathways in the body.
In 1944, Oswald Avery first outlined DNA as the transforming principle, which essentially means that DNA transform cell properties.
2. The Nucleus
The nucleus is the headquarters of the cell.
It is the most obvious organelle in any
eukaryotic cell and appears as a large dark
spot in EUKARYOTIC cells. It controls all
cell activity.
3. The Nucleus is a membrane-enclosed
organelle which house most of the
genetic information and regulatory
machinery responsible for providing the
cell with its unique characteristics.
4. THE NUCLEUS:
FUNCTIONS
It stores the cell's hereditary material, or DNA.
Site of DNA replication
Site of DNA transcription to mRNA
Ribosomal formation
Nucleolus: RNA & protein required for ribosomal
synthesis
It coordinates the cell's activities, which include
growth, intermediary metabolism, protein
synthesis, and reproduction (cell division) by
regulating gene expression.
5. THE NUCLEUS:
STRUCTURE
The contents of the nucleus are enclosed by a
complex nuclear envelope.
Included within the nucleus are:
1- Chromatin
2- Nucleoplasm/ Nuclear matrix
3- Nucleolus (concentrated area of chromatin,
RNA and proteins)
9. The NUCLEAR ENVELOPE (NE)
The nuclear envelope completely encloses the
nucleus and separates the cell's genetic
material from the surrounding cytoplasm,
serving as a barrier to prevent
macromolecules from diffusing freely between
the nucleoplasm and the cytoplasm.
10. The NE consists of two cellular membrane, an
inner and an outer membrane, arranged parallel
to one another and separated by 10 to 50
nanometers (nm).
The outer nuclear membrane is continuous with
the membrane of the rough endoplasmic
reticulum (RER), and is similarly studded with
ribosomes.
The space between the membranes is called the
perinuclear space and is continuous with the RER
lumen.
11.
12. The inner surface of the NE is bound to a thin
filamentous network (lamins polypeptides)
called the nuclear lamina. It provides
mechanical support to the NE and seeves as
sites for attachment for chromatin fibers.
Mutations in the lamin genes are responsible
for several distinct human diseases (e.g. a rare
form of muscular dystrophy).
13. THE NUCLEAR PORE
The nuclear pores are the gateways across
which movement of RNAs and proteins takes
place between the nucleus and cytoplasm in
both direction.
Proteins synthesized in the cytoplasm cross
the nuclear envelop to initiate replication and
transcription of genetic material. Similarly,
mRNA,tRNA and ribosomal subunits built in
the nucleus cross through the nuclear pores to
the cytoplasm.
14. The pore is 100 nm in total diameter and
consists of around 100 proteins which allows
the free passage of small water-soluble
molecules while preventing larger molecules,
such as DNA and proteins.
The nucleus of a typical mammalian cell has
about 3000 to 4000 pores throughout its
envelope.
15. CHROMATIN
The interphase chromosomes is present in a highly
extended nucleoprotein fibers called chromatin.
Chromatin is the complex of DNA,RNA and
protein (Histones and Non-Histomes) that makes
up chromosomes.
Each unreplicated chromosome contains a single
continuous DNA molecule.
The mitotic chromosome represents a highy
condensed structure (10000:1)
18. Replicated
chromosome
P arm
kinetochore
centromere
Q arm
sister chromatids
19. Each human somatic cell contains 23 pairs
of different chromosomes ( DIPLOID
CELLS) .
GAMETES (sperm and egg cells) have one set
of 23 chromosomes ( HAPLOID CELLS).
One member of each pair is derived from the
individual's father, and the other member is
derived from the mother. One of the
chromosome pairs consists of the sex
chromosomes.
20. In normal males, the sex chromosomes are a Y
chromosome inherited from the father and an
X chromosome inherited from the mother.
Two X chromosomes are found in normal
females, one inherited from each parent.
The other 22 pairs of chromosomes are termed
autosomes. The members of each pair of
autosomes are said to be homologs, or
homologous, because their DNA is very
similar. The X and Y chromosomes are not
homologs of one another.
21. Human Chromosomes
Chromosomes are the physical carriers
of genetic information.
The packaging of DNA into
chromosomes involves several orders
of DNA coiling and folding.
22. LEVELS OF CHROMATIN ORGANIZATION
The structure of chromatin varies considerably as
the cell progresses through the cell cycle. The
changes in structure are required to allow the
DNA to be used and managed.
23. Chromatin Function
Package DNA into a smaller volume to fit in
the cell.
Strengthen the DNA to allow mitosis and
meiosis
Serve as a mechanism to control
expression.
24.
25.
26. Simplified diagram of proposed solenoid
model of DNA coiling which leads to the
visible structure of the chromosome.
27. NUCLEOPLASM
The nucleoplasm is a highly viscous liquid
that surrounds the chromosomes and
nucleoli. Many substances such as
nucleotides (necessary for purposes such as
the replication of DNA) and enzymes (which
direct activities that take place in the nucleus)
are dissolved in the nucleoplasm.
28. Nucleolus
:
The prominent structure in the nucleus
is the nucleolus.
The nucleolus produces ribosomes,
which move out of the nucleus and
take positions on the rough
endoplasmic reticulum where they are
critical in protein synthesis.