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’.

1. NUCLEUS
GAURAV
19mslsbf03
M.Sc Life science (Bioinformatics)
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2. Contents
Discovery of nucleus
 Evolution of nucleus
 Structure of nucleus
 Function of nucleus
 Diseases related with nucleus

3. Discovery of
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.

4. What is
nucleus of a
cell?
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

5. Evolution of
Nucleus
Four major hypotheses have been proposed to explain the existence of
the nucleus :-
 Syntrophic model : proposes that a symbiotic relationship
between the archaea and bacteria created the nucleus-containing
eukaryotic cell.
 Second model : proposes that proto-eukaryotic cells evolved from
bacteria without an endosymbiotic stage.
 Viral eukaryogenesis model : proposes that the membrane-bound
nucleus, along with other eukaryotic features, originated from the
infection of a prokaryote by a virus. The suggestion is based on
similarities between eukaryotes and viruses such as linear DNA
strands, mRNA capping, and tight binding to proteins
(analogizing histones to viral envelopes).
 Exomembrane hypothesis : suggests that the nucleus instead
originated from a single ancestral cell that evolved a second exterior
cell membrane; the interior membrane enclosing the original cell
then became the nuclear membrane and evolved increasingly
elaborate pore structures for passage of internally synthesized
cellular components such as ribosomal subunits.

6. Structure of
nucleus
The nucleus is the largest organelle in animal cells.
In mammalian cells, the average diameter of the nucleus is
approximately 6 micrometres (µm), which occupies about
10% of the total cell volume.
The contents of the nucleus are held in
the nucleoplasm similar to the cytoplasm in the rest of the
cell. The fluid component of this is termed as the nucleosol,
similar to the cytosol in the cytoplasm.

7. Contd…

8. Contd…
An electron micrograph of a section through an animal cell nucleus (from an insect
cell) showing heterochromatin (H), euchromatin (E) and the nucleolus with its fibrous
centre (FC) and peripheral fibrous region (PF).

9. Components
of nucleus
1.Nuclear envelope
Structural feature:
The nuclear envelope, otherwise known as nuclear membrane,
consists of two cellular membranes, an inner and an outer
membrane, arranged parallel to one another.
The space between the membranes is called the perinuclear space
and is continuous with the RER lumen
Functional aspect:
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. Contd…
2. Nuclear pores
Structural feature:
Nuclear pores provide aqueous channels through the envelope.
The pores are 100 nm in total diameter.
The gap through which molecules freely diffuse is only about 9 nm
wide.
A number of 3000 to 4000 pores are present in the envelope,
each of which contains an eightfold-symmetric ring-shaped
structure at a position where the inner and outer membranes fuse.
Functional aspect:
passage of small water-soluble molecules while preventing larger
molecules, such as nucleic acids and larger proteins, from
inappropriately entering or exiting the nucleus.
Most proteins, ribosomal subunits, and some DNAs are
transported through the pore complexes.

11. Contd…
3.Nuclear lamina
Structural feature :
The nuclear lamina forms an organized meshwork on the internal
face of the envelope, while less organized support is provided on
the cytosolic face of the envelope. nuclear lamina is composed
mostly of lamin proteins.
Like all proteins, lamins are synthesized in the cytoplasm and later
transported to the nucleus interior, where they are assembled
before being incorporated into the existing network of nuclear
lamina
Functional aspect : provide structural support for the nuclear
envelope and anchoring sites for chromosomes and nuclear pores

12. Contd…
4.Nucleolus
Structural Feature:
The nucleolus is the largest of the discrete densely stained,
membraneless structures known as nuclear bodies found in the
nucleus.
 It forms around tandem repeats of rDNA, DNA coding for ribosomal
RNA (rRNA). These regions are called nucleolar organizer
regions(NOR)
 When observed under the electron microscope, the nucleolus can be
seen to consist of three distinguishable regions: the innermost fibrillar
centers (FCs), surrounded by the dense fibrillar component (DFC) (that
contains fibrillarin and nucleolin), which in turn is bordered by
the granular component (GC) (that contains the
protein nucleophosmin).
Functional aspect:
 Main roles of the nucleolus are to synthesize rRNA and assemble
ribosomes.

13. Contd…
5.Chromosomes
Structural feature:
The cell nucleus contains the majority of the cell's genetic material in the form
of multiple linear DNA molecules organized into structures
called chromosomes.
 Each human cell contains roughly two meters of DNA.
 During most of the cell cycle these are organized in a DNA-protein complex
known as chromatin, and during cell division the chromatin can be seen to
form the well defined chromosomes familiar from a karyotype.
 A small fraction of the cell's genes are located instead in the mitochondria.
 There are two types of chromatin, Euchromatin is the less compact DNA
form, and contains genes that are frequently expressed by the cell.The other
type, heterochromatin, is the more compact form, and contains DNA that is
infrequently transcribed.
 During interphase the chromatin organizes itself into discrete individual
patches,[called chromosome territories.Active genes, which are generally
found in the euchromatic region of the chromosome, tend to be located
towards the chromosome's territory boundary.

14. Chromosomes
c0ntd…
Functional aspect:
 Chromosome is the most condensed form of DNA . So its
function lies in the fact that which are performed by DNA .
 The chromosome holds not only the genetic code, but many
of the proteins responsible for helping express it. Its complex
form and structure dictate how often genes can be translated
into proteins, and which genes are going to be translate.

15. Diseases
related to
Nucleus
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 laminA/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 laminA/C gene were
attributed to a range of tissue-specific degenerative conditions,
collectively known as the 'laminopathies’.

16. Down
syndrome
Down syndrome is a genetic disorder caused when abnormal cell
division results in an extra full or partial copy of chromosome 21.
This extra genetic material causes the developmental changes
and physical features of Down syndrome.
Down syndrome varies in severity among individuals, causing
lifelong intellectual disability and developmental delays.
It's the most common genetic chromosomal disorder and cause of
learning disabilities in children.
It also commonly causes other medical abnormalities, including
heart and gastrointestinal disorders.

17. Phenylketonuria
Disease (PKU)
Phenylketonuria (PKU) is an inborn error of metabolism that
results in decreased metabolism of the amino acid phenylalanine.
Untreated, PKU can lead to intellectual disability, seizures,
behavioral problems, and mental disorders.
It may also result in a musty smell and lighter skin.
A baby born to a mother who has poorly treated PKU may have
heart problems, a small head, and low birth weight.
Phenylketonuria is a genetic disorder inherited from a person's
parents.
It is due to mutations in the PAH gene, which results in low levels
of the enzyme phenylalanine hydroxylase.
This results in the buildup of dietary phenylalanine to potentially
toxic levels.
It is autosomal recessive, meaning that both copies of the gene
must be mutated for the condition to develop

19. References
 https://www.123rf.com/photo_128230633_stock-vector-structure-
of-nucleus-parts-of-the-cell-nucleus-nuclear-lamina-and-
membrane-pore-nucleoplasm-and-nucl.html
 https://www.cronodon.com/BioTech/Cell_Nucleus.html
 https://www.shutterstock.com/search/cell+nucleus
 https://socratic.org/questions/how-was-the-nucleus-was-
discovered
 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3101846/
 http://biologyofcells.blogspot.com/2007/12/nucleolus.html
 https://biologydictionary.net/chromosome/
 https://ghr.nlm.nih.gov/condition/phenylketonuria
https://en.wikipedia.org/wiki/Phenylketonuria