Nucleus

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) CELL B I O L O G Y

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 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’.

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

18. 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