Nucleus of cell

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NUCLEUS,THE MAJOR PART OF CELL

 🟦 Introduction
*Nucleus is the biggest organelles of a cell.
*It surrounded by a layered plasma membrane 
*In the protoplasmic body all hereditary document present.
*Nucleus is called the brain of cell.

🟦 Discovery
*Leeuwenhoek(first discovered nucleus in RBC of fish blood)

 *Robert Brown (1831-in the root of orchid,and also named it)

 *Fontana (1781- discovered nucleolus inside nucleus)

 *Stasburger(1882-described nucleoplasm)

 *Flemming (1879- discussed about chromatin of nucleus)

 *J. Hammerling(1953- discussed about the hereditary influence of nucleus).

 🟦 Origin
*It is assumed that Nucleus is evolved from protonucleus.
*Nuclear membrane is absent in prokaryotic nucleus
*only naked chromatin substances (DNA) present in cytoplasm.
*In a ideal nucleus chromatin substances place together and surround by nuclear membrane.

 🟦 Site
*In eukaryotic cells nucleus present at the middle.
*but depending upon the digestion system of cell, nucleus often change its position.
*when Vacuole form in plant cell, nucleus shifted to peripheral part.

 *Nucleus is absent in RBC of mammals and sieve tube of phloem in higher class plant.


🟦 Number
*Generally there is one nucleus in one cell.
*2 nucleus- in cell of unicellular Paramecium ,Liver cell and cartilaginous cell of vertebrate

 *poly nucleus- has numerous number of Nucleus,this type of cell called cenocyte.


Algae- Vaucheria
Fungi- Rhizopus
Protozoa- Opalina
Bone cell of mammals.

 🟦 Nature
*Eukaryon- if a cell contain one type of Nucleus.
*Homokaryon/dikaryon-if 2 same of Nucleus present in single cell.
*polykaryon- one cell contain one type of numerous nucleus.
*Heterokaryon-2 different types of Nucleus present in one cell.
*Synkaryon- if 2 type of Nucleus joined to form a Nucleus,and present in a cell called synkaryon.
Clear your concept with this video

 *Amphinucleus-Diploid (2n) Somatic cells.
*Heminucleus- haploid (n) reproductive cell.
*Micronucleus and Macronucleus-a cell contain 2 Nucleus, larger one is macronucleus; smaller one is micronucleus.
*Pronucleus-Sperm (n) and Ovum (n) before fertilization.


🟦 Shape
*Rounded- Cuboid epithelial cell.
*Oval shaped- Columnar epithelial cells
*Flat plane like-Squamous epithelial cells

*Kidney shaped- WBC-Besophil

*Horse bow shaped- present in Verticella

*Present of lobes- Neutrophils,
 eosinophils

*Elongated Nucleus- smooth muscle

*Convex Nucleus- Amoeba

*Branched-silk gland of silk moth

*garland shaped- Present in the cell of Stentor


🟦 Size
*A Nucleus in interphase has a diameter of 5-25 μm.
*As per Hertwig,
              
Where,
NP- nucleoplasmic index
Vn- volume of Nucleus
Vc- volume of cytoplasm

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