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
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
Nucleus” is a Latin word meaning Kernel
It is the “CONTROL CENTER” of the cell
Average diameter of nucleus is 6um, which occupies around 10% of cell volume
Nuclear Envelope
Nuclear Pores and complex
Nuclear lamina
Chromosomes & Chromatin
Nucleolus
Nucleoplasm
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
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
Nucleus” is a Latin word meaning Kernel
It is the “CONTROL CENTER” of the cell
Average diameter of nucleus is 6um, which occupies around 10% of cell volume
Nuclear Envelope
Nuclear Pores and complex
Nuclear lamina
Chromosomes & Chromatin
Nucleolus
Nucleoplasm
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
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Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
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Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
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2. History
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
Robert Brown
1773-1858
3. Characteristics of nucleus
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
4. Functions of nucleus
Stores genetic information (DNA & RNA)
DNA replication occurs in the nucleus which is
then passed to daughter cells
Enables the synthesis of nearly all proteins
through the synthesis of RNA.
Houses the nucleolus which is the site of
production of ribosomes
Selective transportation of regulatory factors and
energy molecules through nuclear pores
5. Nuclear organization in
eukaryotes
Nucleus occupies approximately 10 % of the total cell
volume. Structural component of nucleus are:
Nuclear envelope
Nuclear matrix and nuclear lamina
Nucleoplasm
Nucleolus
Chromatin
6. Nuclear Envelope
Boundary of the nucleus that
separates the contents of the
nucleus from the cytoplasm
Provides structural framework of
the nucleus
Act as a barrier that prevent the
free passage of molecules between
nucleus and cytoplasm
Consist of two membranes : outer
and inner membrane
7. Nuclear Envelope (contd
Thickness of each membrane is around 7-8 nm,
encloses a perinuclear space between them (20-40
nm thick)
Outer membrane continues with ER membrane has
ribosomes attached on it
Inner membrane have proteins which bind the
underlying nuclear lamina.
Have number of pores called as nuclear pore
comples, required for transport of molecules between
nucleus and cytoplasm.
8. Nuclear lamina
A fibrous network underlying the inner
nuclear membrane
Provides structural support to nucleus
Composed of fibrous proteins (60-80 kd)
lamins
Mammalian cells have 3 lamin genes: A,
B and C
Lamin proteins associate with each
other to form higher order structure.
Binds to inner nuclear membrane
through lamin binding proteins such as
emerin and LaminB receptor.
Mutations in lamin genes is responsible
for various disease such as progeria.
10. Progeria
Caused by a mutation in gene
LMNA(Lamin-A)
LMNA gene produces the LaminA
protein, which is the structural
scaffolding that holds the nucleus
of a cell together
Defective Lamin A protein makes
the nucleus unstable. That nuclear
instability appears to lead to the
process of premature aging in
Progeria.
11. Nuclear Pores Complex
Only channels for the transport of
different molecules between
nucleus and cytoplasm
Have a diameter of 120 nm and
approx. molecular mass of 125
million daltons
Composed of 30 different proteins
, present in multiple copies called
nucleoporins
Nucleoporins lining the central
channel have multiple FG repeats
Small molecules(20-40kd) diffuse
Large molecules are transported
through central channel
12. Nuclear Pores Complex (contd.)
Consists of eight spokes arranged around a central
channel
spokes are connected to rings at the nuclear and
cytoplasmic surface
Spoke ring assembly is anchored in nuclear envelope
at the site of fusion of inner and outer nuclear membrane
Protein filaments extend from both sides giving a
basket like apperance on the nuclear side
13. Transport of proteins to and from the n
Proteins needs to be transported to nucleus have a
nuclear
specific amino acid sequence known as
localization signal (NLS)
NLS is recognized by the nuclear transport receptor
which directs their transport through nuclear pore complex
NLS first identified in SV 40 by Alan Smith and
colleagues in 1984
NLS are short sequence of amino acids rich in basic
amino acids( lysine and arginine)
Could be present as a single stretch (eg. SV40), or as a
bipartite sequence(eg. Nucleoplasmin)
14. Import of proteins to the nucle
1. NLS of cargo protein is recognized by nuclear transport receptor
importins, resulting in formation of cargo-impotin complex.
2. The complex of cargo protein and importins docks with the
cytoplasmic filament of NPC and complex moves through nuclear
pore complex
3. Once inside the nucleus RanGTP binds to the complex and fascilitate
the release of cargo protein
4. Importin-Ran/GTP complex than exported back through nuclear pore
complex
5. In the cytoplasm GTP is hydrolyzed to GDP by Ran GAP releasing the
importin which can be used again
6. Ran GDP is transported back to nucleus by its own transporterNTF2
16. Export of proteins from nucleu
1.Proteins to be exported from nucleus have nuclear export signals
(NES), they bind to exportins and RaGTP forming a complex.
2.The complex moves to cytoplasm where GTP is hydrolyzed to GDP
fascilitating the release of cargo protein and exportin
3. Exporins and Ran GDP are transported back to the nucleus
17. Regulation of nuclear protein im
Import of proteins such as transcription factor is
regulated in by two mechaisms:
1.In one mechanism transcription factors such as
NF-kB bound to some inhibitory proteins (IkB) which
masks their NLS, so they remain in cytoplasm,
whenever some signal is their ,inhibitory protein is
phosphorylated and degraded and the protein can be
transorted to nucleus
2.In another mechanism transcription factor is itself
posphorylated (eg. Pho4), which prevents its
transport to the nucleus.
19. Internal organization of
nucleus
Loose network of nuclear lamina extends to the
interior of nucleus
These lamins serves as site of chromatin
attachment
Chromatin within the nucleus is organized into
large loops of DNA
Specific region of loops are bound to lamin matrix
bylamin binding proteins in chromatin
20. Chromosome and chromatin
Highly condensed chromatin-
hetro chromatin, transcriptionally
inactive
Decondensed chromatin-
euchromatin, distributed throughout
the nucleus, transcriptionally active
Each chromosome occupies a
distinct teritory, with cetromere and
telomere attached to opposite sides
of nuclear evelope
21. Sub-compartments within nu
Have distinct region for various processes
Contains multiple clustered site for DNA replication
Speckles: storage site for splicing comonents
PML bodies: site for transcriptionaly regulatory proteins
Involved in acute promyelocytic leukemia
Cajal bodies: enriched in small RNPs, functions as site
of RNP assembly and processing
Nucleolus: site for ribosome synthesis
22. Nucleolus
Largest structure present inside the boundaries of the
nucleus
Dark staining zone in center of nucleus
Site of rRNA trascription and processing
Main components are ribonucleic acid (RNA),
deoxyribonucleic acid (DNA) and proteins
Known as ribosome production factory
23. Ribosomal rRNA genes
Nucleolus has genes for 5.8s, 18s and 28s rRNA
Ribosomal rRNA genes are present in tandom arrray
Around 200 copies of genes coding for 5.8s, 18s and 28s rRNA,
present on chromosome 13, 14, 15, 21 and 22
5s rRNA gene is present outside nucleolus on chromosome1 in a
tandom array
5.8s, 18s and 28s are transcribed as a single unit by RNA
polymerase 1, yielding 45s pre-rRNA.
Pre-rRNA is processed to 18s rRNA of 40s subunit and 5.8s,28s
rRNA of 60 s subunit of ribosomes