Question

,,,,,,what is nucleus.....?

Answer 1

Nucleus is the dense round structure present in the cell. It contains DNA and genetic material of the cell.In animals it's usually located at the centre but in plant cells it is located at the corners.
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Answer 2

Hey !

Let me give you a brief introduction about ''NUCLEUS''

• Nucleus was discovered by Robert Brown in 1831.
• Every eukaryotic cell consists of at least one, almost spherical, dense, highly specialised structure called as nucleus (exceptions-sieve tube element of mature phloem in plants, RBCs of mammals)
• All the metabolic activities of a cell are under the control of nucleus.
• Chemically nucleus consists of 70% proteins, 20% DNA, 5% RNA and 3% lipids.
• Nucleus is considered to be the vehicle of heredity as it contains the genetic information for reproduction, development, metabolism as well as behaviour of irritability organism. Nucleus is the smallest unit that shows capacity for metabolism, irritability growth and reproduction.
• The nucleus consists of following parts

1) Nuclear Membrane :- It is double-layered membrane and surrounds the nucleolus of a eukaryotic cell.

2) Nucleoplasm :- It is clear gel-like, ground matrix having ions, proteins, nucleotide and ribosomes. Chromatin threads and nucleolus are also embedded in it.

3) Nucleolus :- Nucleolus was discovered by Fontana in 1781. It is non-membranous sphere-like structure composed of 10% RNA , 85% proteins and 5% DNA. It takes part in the production of ribosomal subunits, RNA and some specific proteins.

4) Chromatin:- It is present in the nucleoplasm as thin-threads. It is made up of DNA basic proteins (histones) and non-histone proteins. During cell divisions, chromatin condenses into chromosomes.

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