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Difference Between Nucleus and Nucleoid


Last updated date: 20th Mar 2023
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In eukaryotic cells, the nucleus is an organelle that stores proteins and RNA. It is the largest and most essential organelle in the cell. In prokaryotes, the nucleoid is an irregularly formed area that contains genetic material.


In eukaryotic cells, the nucleus is a biological cell membrane organelle. It has all of the cell genomes in it. Except for a small fraction of mitochondrial DNA, it is made up of DNA, RNA, and Histones.

The nucleus aids in the control and regulation of cellular processes such as growth and metabolism. It transports genes, which are structures that hold genetic information.

  • Structure

In mammals, the nucleus is the biggest organelle. It has a diameter of around 6 micrometres and occupies roughly 10% of the total cell volume. In the rest of the cell, the contents are put in the nucleus sap or nucleoplasm. It's also called Karyoplasm, and it looks like cytoplasm. Nucleoplasm is a matrix that looks like a gel.

Time-lapse microscopy can reveal the dynamic behaviour of the structure in the nucleus. Live-cell imaging is the study of cells using this microscope. It aids in the visualisation of mitotic activity such as nuclear rotation.

  • Nuclear Membrane

The genetic components are encased in two membranes that make up the nuclear membrane. In eukaryotic cells, these membranes surround the nucleus.

It is made up of two cell membranes, one inner and one exterior, that are laid out parallel to one other. These membranes are 10 to 50 nanometers apart (nm).

Phospholipids form a lipid bilayer in the nuclear envelope. It aids in the nucleus's preservation. 

The major purpose is to aid in the regulation of membrane flow into and out of the nucleus via nuclear pores. Large molecules such as proteins and RNA are exchanged between the nucleus and the cytoplasm through nuclear pores.


Within a prokaryotic cell, the nucleoid is where the genetic information, known as the genophore, is found. Archaea and bacteria, both unicellular creatures, are two types of prokaryotes. Organelles that are membrane-bound do not exist in these creatures.

There is no membrane surrounding the nucleoid. It connects the cytoplasm and is linked to the cell membrane. It also doesn't have a consistent shape or size. Under a light microscope, it may still be separated from the remainder of the cell and identified.

In addition to RNA and proteins, the nucleoid is largely made up of many compact replications of DNA in a continuous thread. Prokaryotic DNA is double-stranded and circular in form. Outside of the nucleoid, DNA can occasionally be detected in other places.

Eukaryotes have a nucleus, which is surrounded by a double membrane and stores their genetic material. The nuclear envelope is another name for it. This membrane aids in the separation of the nucleus' contents from the cytoplasm. Eukaryotic DNA is double-stranded, just as that of prokaryotes.

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FAQs on Difference Between Nucleus and Nucleoid

1. What is Nuclear Lamina?

When it comes to animal cells, the nucleus is provided with mechanical support by intermediate filaments. The nuclear lamina is in the form of a meshwork made up of a protein called the lamin protein that lines the inner surface of the nuclear envelope becoming a part of the nuclear skeletal network thus providing structural support to the nuclear envelope. The lamin protein just like other proteins is synthesized in the cytoplasm and later gets transported to the inside of the nucleus.

2. What is the Function of Nucleoid Associated Proteins (NAPs)?

The NAPs are responsible for the organization of the Nucleoid and they also help in the expression of genes. The NAPs are low molecular polypeptides that are responsible for binding DNA and is capable of altering its shape and further leads the DNA in participating in the process of transcription. The NAPs also can remodel the structure of a Nucleoid.

3. Explain the functions of the Nucleus?

  • The nucleus' primary purpose is to regulate gene expression and DNA replication during the cell cycle. 

  • It aids in the control of an organism's hereditary characteristics. 

  • In the form of thin and lengthy DNA, it stores genetic material such as genes. 

  • Protein synthesis, growth and differentiation, and cell division are among the other functions of the organelle.

  • The nucleus aids in protein and RNA storage in the nucleolus. It aids in the arrangement of messenger RNA generated in the process of protein synthesis.

  • In the nucleolus, the nucleus aids in the creation of ribosomes. These ribosomes are protein-producing machines. 

4. How are Nuclei and Nucleoid different from each other? State briefly in a tabular form.

Basis of Difference




Eukaryotes have a "nucleus" that stores their Genetic information.

Prokaryotes have a nucleoid that stores their genetic material.





Several chromosomes

Only one chromosome





Double layer membrane

No membrane


It is present here

It is not present here


It is present here

It is not present here


The main composition are DNA, histones, RNA, enzymes, dissolved ions, and other subnuclear bodies

DNA, histones, RNA, and other proteins.

5. What is a Cell?

Living organisms are made up of cells, which serve as both structural and functional units. In 1665, Robert Hooke made the discovery. In Latin, a cell refers to a small space. Unicellular Organisms, which include bacteria, protozoa, and yeasts, are made up of a single cell, whereas Multicellular Organisms, which are made up of many cells, are complex organisms.

Three key functional areas exist in every cell:

1. The cell membrane

2. The nucleus 

3. Cytoplasm

6. When the nucleus of a cell is removed, what happens?

The nucleus is the cell's control centre and contains genetic material. It is the cell's brain, and it is in charge of the majority of its tasks. The cell will not be able to operate correctly if the nucleus is removed, and it will not be able to grow. 

The cell's metabolic functions will come to a halt. The cell will become incapable of cellular reproduction. The cell will also be unsure of what to do, making cell division impossible.

Protein synthesis would also go wrong or inappropriate proteins would be generated, resulting in cell death.

7. What are Organelles?

Organelles are specialised structures that perform a range of roles within cells. The word translates to "little organs." Organelles provide specialised functions to keep a cell alive in the same way that organs such as the heart, liver, stomach, and kidneys serve specific roles to keep humans alive.

Among the most important cell organelles are nuclei, which store genetic information, mitochondria, which supply chemical energy, and ribosomes, which create proteins.