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Nucleus: Structure and Function

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The nucleus is a double membrane-bound organelle that is present in eukaryotic cells. The nucleus contains the cell’s genetic material in the form of DNA, which is organized into structures called chromosomes. The nucleus is usually the largest organelle in the cell and is covered by a double membrane called the nuclear envelope, on which nuclear pores are present that allow the movement of certain molecules in and out of the nucleus.

Within the nucleus, the DNA is organized into long strands of chromatin, which can condense into discrete chromosomes during cell division. The nucleus also contains a nucleolus, which is a structure that produces ribosomes, the cellular machines that synthesize proteins.

What is a Nucleus?

The nucleus is part of the cell that is most essential (plural: nuclei). It comes from a Latin term that translates to “nut kernel.” The nucleus is discovered by Robert Brown in 1831.

A double-membraned organelle found in eukaryotic cells known as a nucleus, it is the house of genetic material.

The nucleus is the unique characteristic of eukaryotic cells and is only present in eukaryotes. Prokaryotic cells don’t have a true nucleus, they have nucleoids.  However, although coming from eukaryotic species, some cells, like RBCs, lack a nucleus.

Also Read: Difference between Prokaryotic and Eukaryotic Cell

Characteristics of Nucleus

  • It is typically the cell organelle present in almost every cell.
  • The nucleus is covered via 2 membranes.
  • The nuclear envelope is the structure that surrounds it.
  • The cytoplasm and the nucleus’s contents are separated by the nuclear membrane.
  • The chromosomes of the cell are present within the nucleus.
  • The chromosomes, which contain DNA, supply the genetic information which is necessary for the synthesis of various cell components as well as for the generation of life.
  • The presence of nuclear pores on the envelope of the nucleus facilitates the movement of substances between the nucleus and the cytoplasm.

Structure of Nucleus

The nucleus is divided into different subparts, those are:

Nuclear Membrane

Nuclearv envelop is the other name of the nuclear membrane. It is a double membrane structure that differentiates the cytoplasm and nucleoplasm of the eukaryotic cell. The nuclear membrane is composed of 2 lipid layers, one is outer and the other one is inner. The space present between the 2 layers is known as periplasmic space. Porous structures are present over the nuclear membrane which helps in the transportation of TFs, proteins, and RNAs.


Chromosome is a structure that is composed of DNA and proteins present in the nucleus. These are the thread-like structures that are seen under the microscope at the time of cell division. The DNA is highly coiled over the histone protein known as chromatin. Chromatin can further divide into 2: Heterochromatin (highly condensed DNA) and euchromatin (loosely packed DNA). Chromosomes are numbered according to their size, with the largest being chromosome 1 and the smallest being the sex chromosomes, X and Y.

Nucleic Acid

Nucleic acids are large biomolecules, or macromolecules, present in all living cells. They are responsible for carrying and transmitting genetic information from one generation to the next and are essential for the function and survival of cells and organisms. 2 types of nucleic acid are present those are DNA and RNA. These are made up of four building blocks called nucleotides – adenine (A), cytosine (C), guanine (G), and thymine (T) – they linked together in a specific sequence to form a long, double-stranded helix. In the case of RNA Uracil is present in place of Thymine.

Nuclear Sap

A clear, transparent, homogenous colloidal liquid is enclosed in the nuclear membrane. The nucleoplasm is a complex solution containing ions, enzymes, nucleotides, and various other biomolecules necessary for the cell’s genetic activity. The nucleoplasm contains genetic material in the form of chromatin, which is the complex of DNA, histone proteins, and other associated proteins. Within the nucleoplasm, there is also the nucleolus, which is a dense region that produces ribosomes, the cellular machines that synthesize proteins.


The unique structure inside the nucleus of eukaryotic cells is called the nucleolus. It mostly takes involved in ribosome assembly, changing transferring RNA, and detecting oxidative stress. RNA and proteins, which develop around particular chromosomal areas, make up the nucleolus. It is a significant part of the nucleus. The structural elements are made up of the sequence of DNA or RNA, as well as other elements. RNA, DNA, and proteins make up most of the nucleolus.

Diagram of Nucleus

Nucleus Diagram


Function of Nucleus

  • The nucleus regulates the cell’s growth and reproduction as it contains the cell’s genetic information.
  • Proteins would move across the nucleus with help of a signal called a nuclear export signal.
  • The genetic makeup of a cell is contained in the nucleus, which is covered with a double membrane-bound structure.
  • In addition to serving as a DNA storage space, it also serves as the location of various significant cellular functions.
  • In the nucleus, one’s DNA can be duplicated first and foremost. DNA replication is the process that creates an exact duplicate of the DNA.
  • Cell division begins with creating two exact replicas of the parent or host, with each new cell receiving a unique set of instructions.
  • Second, transcription takes place in the nucleus. Different RNA types are produced by transcription from DNA.
  • DNA gets transcribed into RNA, and then into proteins, according to the fundamental biological principle.

FAQs on Nucleus

Q1: What is the nucleus?


All genetic information and other instructions necessary for the cellular functions of a cell are present in the double membrane organelle known as the nucleus. It is one of the biggest organelles and is only present in eukaryotic cells.

Q2: Nucleus is discovered by?


Robert Brown discovered the nucleus in 1831.

Q3: Describe various functions of the nucleus.


The nucleus serves two main purposes:

  • It is in charge of keeping the DNA or other genetic material within the cell.
  • It is in charge of organizing a variety of crucial cellular processes, including the synthesis of proteins, cell division, growth, and a number of other crucial operations.

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Last Updated : 20 Apr, 2023
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