Difference Between Nucleus and Nucleoid


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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