Dr Mah Jabeen Muneera
Assistant Professor
Department of Anatomy
KEMU
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Command center
DNA replication
Synthesis & processing of RNA
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Location
Shape
Nuclear envelope
and nuclear lamina
Chromatin
› DNA
› RNA
› Nucleoproteins

Nucleolus
Sequencing was successfully completed
in 2003
 Entire length (1.8m)
 Genetic information packaged in all 46
chromosomes.
 2.85-billion base pair sequence of
nucleotides-- 23,000 protein-coding
genes.
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DNA protein (histone & other structural
proteins) complex
 Euchromatin:
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› It is stretched out so that genetic information
in the DNA can be read and transcribed
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Heterochromatin:
› Highly coiled or condensed form of
chromatin, not available for transcription
Liver cells and neurons- active in protein
secretory activity – lightly stained nucleus
due to euchromatin
 Lymphocytes and sperm- inactive cellsdarkly stained nucleus due to
heterochromatin
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Dying cells have visible nuclear alterations.
These include
 karyolysis,
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› Disappearance of nuclei due to complete
dissolution of DNA by increased activity of
DNAase
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Pyknosis,
› Condensation of chromatin leading to shrinkage
of the nuclei (dense basophilic masses)
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karyorrhexis,
› Fragmentations of nuclei
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Discovered in 1949 by Barr
and Bartram in the nerve
cells of female cats
X chromosome
heterochromatin in an
interphase cell
Screening for X
chromosome aneuploidiesbuccal smears or blood
smears
Buccal- adjacent to the
nuclear envelope
Neutrophils- drumstick
shaped appendage on
one of the nuclear bodies
syndrome
karyotype
Sex
chromatin
Nuclear
sex
Cytogeneti
c sex
Klienfelters
47 XXY
+ve
female
male
Turners
45XO
_ve
male
Female
Superfemal
e
47XXX
++
female
Female
Jacobs
47XYY
_ve
male
male
Three regions:
 Fibrillar centers contain DNA
loops of five different
chromosomes (13, 14, 15, 21,
and 22) that contain rRNA
genes, RNA polymerase I, and
transcription factors.
 Fibrillar material (pars
fibrosa) contain ribosomal
genes that are actively
undergoing transcription and
large amounts of rRNA.
 Granular material (pars
granulosa) represents the site
of initial ribosomal assembly
and contains densely packed
preribosomal particles.
Nucleoskeletal
 Nuclear organization
 Cell cycle regulation
 Differentiation
 Gene expression

Phosphorylation of the nuclear lamins
and other lamina-associated proteins ;
Kinases
 Proteins become soluble-- nuclear
envelope disassembles
 The lipid component -- cytoplasmic
vesicles
 chromosomes attach to the
microtubules of the mitotic spindle
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Anaphase: Phosphatases are
activated to remove the phosphate
residues from the nuclear lamins
 Telophase (early): Lamins repolymerize
around each set of daughter
chromosomes
 Vesicles of lipid components and
structural membrane protein
components fuse.
 Telophase (late): Formation of a
nuclear envelope is complete
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Emery Dreifuss Muscular Dystrophy
Nuclei pushed towards plasma
membrane
 Adipocytes
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Mucous Acini