Difference Between Nucleus and Nucleoid


Main Difference

The main difference between Nucleus and Nucleoid is that Nucleus is a membrane-bounded organelle, whereas Nucleoid lacks a bounded membrane.

Nucleus vs. Nucleoid

The nucleus is a well-organized organelle and is larger in size. Nucleoid is a poorly-organized organelle and smaller in size. The nucleus is comprised of both nucleoplasm and nucleolus, while the nucleolus and nucleoplasm both are absent in the case of the nucleoid. The nucleus consists of enzymes, DNA, RNA, histones, dissolved ions, and other subnuclear bodies. Nucleoid consists of just DNA, RNA, histones, and other proteins. The nucleus contains the whole DNA of an organism. Nucleoid contains only the one circular DNA molecule.


The nucleus is rich in DNA or genetic material. Nucleoid is rich in RNA and involved in RNA synthesis. The process of transcription takes place in the nucleus through which mRNA is formed for further protein synthesis. Nucleoid involves in the formation of coenzymes and cofactors like NAD, FAD. The nucleolus is present inside the nucleus. Nucleoid lacks the nucleolus. In nucleus structure of DNA is formed with the help of histones proteins. In the nucleoid, DNA is compact with nucleic acid proteins.

The nucleus plays an important role in housing the genetic material as well as helps to run the process of transcription, ribosomes biogenesis, and also helps in the DNA replication process. However, the nucleoid is only taken part in housing the genetic material. The nucleus is concealed with the nuclear envelope. Nucleoid is said to be a naked organelle. The nucleus contains the whole genome of an organism that covers all the genetic information. Nucleoid contains only a circular DNA having genetic information.


Comparison Chart

It is a distinctly shaped organelle found in most eukaryotesIt has not a distinct shape and found in prokaryotes
Spherically shaped organelleIrregularly shaped organelle
Number of Chromosomes
Possess many chromosomesOnly one chromosome id present
Chromatin Fibers
Found with the chromosomesNot present with the chromosomes
Nucleolus and Nucleoplasm

What is the Nucleus?

The nucleus is one of the most important organelles of all eukaryotic organisms. The nucleus is oval-shaped and found at the center of the cell. The nucleus is further composed of the nucleolus, chromosomes, nuclear pores, nuclear membrane, and nucleoplasm. In the eukaryotic cell’s nucleus is placed in the cytoplasm but not get mixed in the cytoplasm because the nucleus of the eukaryotic cell is covered by the double-layered membrane. The nuclear pores present on the nuclear membrane are used to exchange the material from the nucleus to the cytoplasm of the cell.

Inside the nucleus, a dense glandular fluid is present. In this nucleoplasm, many nucleolus and chromatin are slings in it. The chromatin is composed of a long coiled double-helix strand of the DNA, which plays an important role in the transmission of genetic material from one generation to the next generation. The nucleus itself is made up of nuclear protein and RNA. The nucleus is also responsible for regulating the different metabolic processes of the cell also plays an important role in performing cell cycle while transmitting the genetic material from one to another generation.

The nucleus holds up all the cell’s DNA and the DNA comprise of all the genetic information. In addition to this nucleus is said to be an ideal cellular organelle to keep all the genetic information, and all the production of cells would take place there. However, the nucleus also plays a role in generating the genetic expressions which are further used to regulate all the activities of the whole cell.

What is Nucleoid?

In prokaryotes like bacteria and algae nucleoid rather than nucleus is present. It has no defined shape or boundaries and still possesses the nucleic acid inside it. It is composed of only a single chromosome that is round in shape and stores all the genetic information regarding the prokaryotes. Like the nucleus, there is no nuclear membrane, and other organized regions surrounded the nucleoid as we discuss that there is no nuclear membrane surrounding the nucleus; that’s why it can’t be distinguished easily in the prokaryotic cytoplasm.

Nucleoid is suspended in the cytoplasm and contains almost all the genetic material of the nucleoid. Nucleoid is also known as “genophore.” Basically, it is just an irregular shaped region. This nucleoid contains a DNA strand, which is a composite of about million base pairs. Some part of the chromosome is also found in the plasmids which are present inside the prokaryotic cytoplasm. The nucleoid is found clearly observed separated from the cytosol under the electron microscope.

The nucleoid is comprised of about 60% DNA. It also consists of RNA and protein, mostly present RNA is mRNA and protein is transcription factor proteins which regulate the gene expression in a prokaryotic organism. Proteins like histones that are used in the looping of DNA don’t involve forming nucleosomes of the nucleotide. The structure of the nucleoid is not always the same; it can be changed by the exposure of ultraviolet radiation. For instance, the nucleoid of E.coli becomes compact and leads to the activation of RecA, a DNA damage repair protein.

Key Differences

  1. The nucleus contains the nucleoplasm, whereas the nucleoid doesn’t contain the nucleoplasm.
  2. Nucleus had a limited membrane; on the other hand, nucleoid doesn’t have a limiting membrane.
  3. In the nucleus, DNA is present along with chromatin fibers; conversely, in nucleoid DNA is present without the chromatin fibers.
  4. The nucleus holds the genetic material of eukaryotes; on the flip side, nucleoid holds the genetic information of prokaryotes.
  5. The nucleus is separated from the cytoplasm because of the nuclear envelope, while the nucleolus isn’t separated from the cytoplasm because it doesn’t possess any nuclear envelope.
  6. The nucleus is a membrane-bounded structure, although nucleoid is a membrane-less structure.
  7. The nucleus is larger and has a proper shape as compared to the nucleolus, which is irregular in shape.
  8. The nucleus contains double membrane and nuclear envelope comparatively nucleoid is a membrane-less or naked organelle.
  9. The nucleus is the main organelle which holds a nucleolus. However, nucleoid is just a spot in prokaryotic organisms where genetic material is present.
  10. Nucleus possesses many nuclear pores on the surface; on the other side, nuclear pores are absent on the nucleoid.


It is concluded that the nucleus housed all the genetic material of eukaryotes, and nucleoid housed the genetic information of all prokaryotes.

Janet White

Janet White is a writer and blogger for Difference Wiki since 2015. She has a master's degree in science and medical journalism from Boston University. Apart from work, she enjoys exercising, reading, and spending time with her friends and family. Connect with her on Twitter @Janet__White