Difference Between Nucleus and Nucleolus

The cell is the most fundamental source of survival in every creature, and the ‘nucleus’ is found in virtually all cells. In all multicellular creatures, the nucleus may be detected. The nucleus is responsible for the cell’s most important activities to sustain an individual’s lifespan. 

Cells also include a nucleolus, which is another essential element. It would be impossible for a creature to operate effectively without the nucleolus. The nucleus and the nucleolus have a few distinctions.

Nucleus vs Nucleolus

The main difference between the nucleus and nucleolus is that the nucleus consists of DNA and holds in the chromosomes whereas the nucleolus is rich in RNA and does not contain the chromosomes. The nucleus has a definite shape because it is bound by a membrane known as ‘nuclear envelope’ whereas the nucleolus has a diffused structure with no bounding membrane around it.

Nucleus vs Nucleolus

When looking at a photograph of a cell, the nucleus is among the most visible components. The nuclei are located at the center of the cell and comprise all of the stranded DNA molecules as well as chromosomes, which encode genetic material. As a result, protecting this portion of the cell is extremely crucial.

The center part where the nucleus is located; is surrounded by a membrane that keeps all of the chromosomes within and distinguishes between the chromosomal material and the various compartments and constituents of the cell that remain outside.

The nucleolus is a particularly specialized component of the nucleus of the cell. The chromosomal materials are not included in a nucleolus. This comprises the machinery required for the cell’s ribosomal RNAs to be generated. Ribosomal RNAs are subsequently transferred into the cytoplasm via the nuclear membrane and its pores, where they join the ribosomal constituent, which is the protein mechanism.

Comparison Table Between Nucleus and Nucleolus

Parameters of ComparisonNucleusNucleolus
StructureThe nucleus is large and spherically structured.The nucleolus is diffused and a tiny structure present inside the nucleus.
FunctionsIt is known as the cell’s brain since it directs all of the cell’s functions.It is responsible for ribosome synthesis and protein synthesis.
ConstituentientsNuclear membrane, nucleoplasm or nucleus sap nuclear mesh, chromatin, and nucleolus are some of the features that make up the nucleus.The fibrillar centre (FC), the densely fibrillar element (DFC), and the granular component are the three primary components of the nucleolus (GC).
PositioningUsually is present in the centre of cytoplasm of the cell.Is present inside the nucleus.
Genetic MaterialsIt consists of DNA.It consists of RNA.

What is a Nucleus?

The nucleus is the most important component of the cell, and the nucleoid, as well as nucleolus, is a part of it. In multi-celled creatures or eukaryotic and bi-cellular organisms, the nucleus is a membrane-bound organelle that is essential for maintaining the entire functioning of that cell.

In multi-celled creatures or eukaryotic and bi-cellular organisms, the nucleus is a bilayer organelle that is essential for maintaining the entire functioning of that cell. The medial and lateral membrane proteins are membranous components.

The purpose of the cell membranes is to keep the genetic information in the nucleus distinct from the cytoplasmic component that surrounds it. Additionally, the cellular barrier inhibits molecules from readily flowing between the cytoplasm and cytoplasmic membrane.

The nucleus is important for capabilities and developing data as well as storing the genetic components from the cell’s DNA. Furthermore, the nucleus guarantees that the genetic material in the DNA is in perfect working order, allowing for normal cell reproduction. Furthermore, the nucleus is in charge of producing genetic expression to keep track of the cell’s correct functioning.

The nuclear membrane is a double-membrane layer that surrounds the nucleus. The nucleus’ outer layer is joined to the RER or Rough Endoplasmic Reticulum. Nuclear apertures are aqueous conduits inside the nuclear membrane.

What is a Nucleolus?

The nucleolus is a structure inside the nucleus that is responsible for ribosome production and assembly. Ribosomes are assembled and transferred to the cytoplasm of the cell, where they function as protein production sites.

The nucleolus of eukaryotes is a well-organized organization with four major anatomical components. The parts can also be classified as follows:

  1. Fibrillar Centers: These are the sites where translational ribosome proteins are made.
  2. Coarse or granular components: These elements have rRNA that interacts to ribosomal proteins before ribosomes are synthesized.
  3. Fibrillar Components in Dense Form: It contains newly produced RNA that links to ribosomal proteins.
  4. Nucleolar vacuoles are exclusively seen in plant tissues and cells with a definite cell wall.

Another vital role of the nucleolus is to protect the cell’s DNA. The nucleolus is in charge of collecting and transcribing RNA, especially ribosomal nucleic acid, or rRNA. Additionally, the nucleolus is in charge of ribosomal protein synthesis, which is required for the cell’s functions to perform.

In eukaryotes, the nucleolus is important in translational RNA production and ribosome synthesis. It also plays a role in signal processing particle assembly and the cell’s noxious stimuli.

Main Differences Between Nucleus and Nucleolus

  1. The nucleus of a cell is considered the main organelle whereas the nucleolus is a sub-organelle of the cell.
  2. The nucleus has a double-layered outer membrane called the nuclear envelope or the nuclear membrane whereas the nucleolar membrane does not have an outer membrane.
  3. The nucleus is rich in DNA but the nucleolus is rich in RNA.
  4. The nucleus is responsible for controlling DNA multiplication and cell division whereas the nucleolus is responsible for ribosomal biogenesis.
  5. The nucleus is a definite organelle whereas the nucleolus is a diffused sub-organelle because of no bounding membrane.


During the life of a cell, the mechanism of nuclear division breaks down part of the cell nucleus. Cellular DNA is duplicated before nuclear division. The nucleus’ building elements, including the nuclear envelope and lamina, are then gradually destroyed, and the nucleolus eventually vanishes. Homologous chromosomes are then divided into two poles.

All nucleus components, including the nucleolus, are regenerated once cell division is completed. As a result, the main distinction between nucleolus and nucleus is how they are organized inside the cell. The nucleolus is the mind of the nucleus, occupying almost 25% of its volume, and the nucleus is the brain of the entire cell.


  1. https://www.biologyonline.com/dictionary/nucleolus
  2. https://www.frontiersin.org/articles/10.3389/fpls.2018.00132/full
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