Dr Mah Jabeen Muneera Assistant Professor Department of Anatomy KEMU

Command center DNA replication Synthesis & processing of RNA

 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.

 DNA protein (histone & other structural proteins) complex  Euchromatin: › It is stretched out so that genetic information in the DNA can be read and transcribed  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 cells- darkly stained nucleus due to heterochromatin

 Dying cells have visible nuclear alterations. These include  karyolysis, › Disappearance of nuclei due to complete dissolution of DNA by increased activity of DNAase  Pyknosis, › Condensation of chromatin leading to shrinkage of the nuclei (dense basophilic masses)  karyorrhexis, › Fragmentations of nuclei

 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 aneuploidies- buccal smears or blood smears  Buccal- adjacent to the nuclear envelope  Neutrophils- drumstick shaped appendage on one of the nuclear bodies

syndromekaryotypeSex chromatin Nuclear sex Cytogeneti c sex Klienfelters47 XXY+vefemalemale Turners45XO_vemaleFemale Superfemal e 47XXX+ femaleFemale Jacobs47XYY_vemale

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

 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

 Emery Dreifuss Muscular Dystrophy

 Nuclei pushed towards plasma membrane  Adipocytes  Mucous Acini