Nucleus- its structure ,function ,shape and size ??

Description on Nucleus it's structure, function, shape and size are given briefly in simple, effective and qualitative way below:-

# Nucleus

Fig:-Nucleus.

--> Nucleus is a spherical dense structure

 present in in cytoplasm of both Plant and 

Animal cell. It is the most prominent and 

largest cell organelle. It has a diameter of 

10 to 12 Micron and occupy about 10% of total 

volume of cell. It is present in the centre of 

cell and  embedded  in cytoplasm. It was 

described by Robot Brown(1831 A.D) in 

orchid cells though it was first observed by 

Anton von Leeuwenhoek. 

# Occurrence of Nucleus.

--> The nucleus is found in all the

 Eukaryotic cells except mature RBC,sieve

 tube cells  of  phloem,tracheids and vessels 

of xylem .The  prokaryotes have primitive

 nucleus cell  called Nucleoid 

 (I.e the nucleus without nuclear membrane

 and nucleolus). 

#Shape and Size of Nucleus.

--> The shape and size of nucleus varies 

from Cell to cell. Generally, the shape of cell

 determines the shape of nucleus .

The nucleus may be ellipsoidal ,cuboidal, 

kidney shaped and even irregular shaped. 

The size of nucleus also differs widely 

which depends upon cytoplasmic- index 

and the number of chromosomes present 

in the nucleus. In young cell, nucleus 

occupy 25% off cell volume while in 

adult cell it occupies about 10% of the cell 

volume. 

# Components of Nucleus. 

 -->Nucleus is made up of four components. They are given below in ponts:-

1.Nuclear membrane

2.Nucleoplasm

3.Nucleolus

4.chromatin reticulum. 

*Explanation of all the component of nucleus is given below:-

Fig:-Components of nucleus. 

1.Nuclear membrane

-->The outermost covering of nucleus is 

considered as nuclear membrane. 

It was first discovered by 𝙀𝙧𝙘𝙡𝙖𝙗 (1845 A. D)

Under electron microscope, it is observed 

that the nuclear envelope is composed of 

two membranes. Each membrane is about 

90 Å thick, lipo proteinous and trilaminar. 

The outer and inner nuclear membranes 

separated by a perinuclear space filled with

 fluid. The outer membrane is continuous 

with the endoplasmic reticulum and is 

studded with ribosomes. The nuclear 

envelope is perforated by pores. These

 pores allow exchange of substances 

between the nucleus and the cytoplasm.

Each nuclear pore is fitted with a 

cylindrical structure, called annulus and

 both collectively form the pore complex or 

pore basket.Nuclear membrane contains 

many small pores called Nuclear pores. 

2.Nucleoplasm

-->It is transparent, semi-fluid, gel-like 

dense ground substance or matrix 

present inside the  nuclear membrane in 

which chromatin reticulum and nucleolus 

are embedded. Nucleoplasm is chemically 

composed of water, nucleotides, sugar, 

enzymes, minerals, lipid, protein, etc. 

3.Nucleolus

Fig:-Nucleolus.

-->It is more denser than nucleoplasm and 

are large spherical  dense structure. It was 

first observed by Fontana (1718 A. D) in the 

skin cell of eel. The term "nucleolus" was

 coined by Bowman(1840 A. D) and it's 

structure was given by Wagner(1840 A. D). 

4.Chromatin reticulum

-->They are net ,thread like, coiled structure

 present in the nucleoplasm . Chromatin 

reticulum by the Union of chromatin

 fibres. They form chromosome on 

condensation during karyokinesis .

# Functions of Nucleus. 

1.It helps in exchange cytoplasm and 

nucleoplasm within the cell through nuclear

 membrane. 

2.Nucleus play significant role in cell division. 

3.It controls/regulate/maintain/guide the

 function of other organelles too. Hence it is

 also called as" 𝙈𝙖𝙨𝙩𝙚𝙧 𝙤𝙧𝙜𝙖𝙣𝙚𝙡𝙡𝙚 𝙤𝙛 𝙧𝙝𝙚 𝙩𝙝𝙚 

𝙘𝙚𝙡𝙡 𝙤𝙧 𝙗𝙧𝙖𝙞𝙣 𝙤𝙛 𝙩𝙝𝙚 𝙘𝙚𝙡𝙡. "

4.𝙉𝙪𝙘𝙡𝙚𝙪𝙨 𝙘𝙤𝙣𝙩𝙖𝙞𝙣𝙨 𝙘𝙝𝙧𝙤𝙢𝙤𝙨𝙤𝙢𝙚𝙨 𝙬𝙝𝙞𝙘𝙝 𝙖𝙧𝙚

 𝙝𝙚𝙧𝙚𝙙𝙞𝙩𝙮 𝙘𝙖𝙧𝙧𝙞𝙚𝙧. 𝙃𝙚𝙣𝙘𝙚, 𝙞𝙩 𝙝𝙚𝙡𝙥𝙨 𝙞𝙣 𝙩𝙝𝙚

 𝙩𝙧𝙖𝙣𝙨𝙛𝙚𝙧 𝙤𝙛 𝙥𝙖𝙧𝙚𝙣𝙩𝙖𝙡 𝙘𝙝𝙖𝙧𝙖𝙘𝙩𝙚𝙧𝙞𝙨𝙩𝙞𝙘𝙨 𝙩𝙤 𝙩𝙝𝙚𝙞𝙧 

𝙤𝙛𝙛𝙨𝙥𝙧𝙞𝙣𝙜𝙨. 

5.it helps to form sperm in male and 

Ovum(plular:Ova) in female. 

6.It helps in the pinocytosis and phagocytosis 

of large sized molecule. 

7.It maintains the shape of nucleus.