The nucleoid is the region of a prokaryotic cell that houses the primary DNA. This lesson briefly discusses the nucleoid and its characteristics and how it compares to the nucleus of the eukaryotic cell.
The cell is the smallest unit of life. Cells come in two basic forms: eukaryotic and prokaryotic. Eukaryotic cells are cells that have a ‘true’ nucleus, or central compartment for DNA, which is genetic material, and other organelles that contain membranes. This nucleus contains a membrane to protect the interior where the DNA is housed.
In a sense, the nucleus is the ‘control center’ of the eukaryotic cell, directing the activities.Prokaryotes, on the other hand, lack organelles and membrane-bound structures within the cell. This means they also lack a ‘true’ nucleus, and therefore, the DNA of the cell is not protected by a nuclear membrane. For prokaryotes, DNA will be housed in a region known as the nucleoid.
What Is the Nucleoid?
The nucleoid is the region in the prokaryotic cell that contains the main DNA material. As a side note, some DNA will be in other sections of the cell, but the primary material will be in the nucleoid.
The nucleoid has an irregular shape compared to the nucleus of eukaryotic cells, which is circular.DNA in the nucleoid is circular and may have multiple copies at any given time. Additionally, DNA in the nucleoid may be supercoiled, meaning it has twists in the circular shape that makes it more compact. As the cells grow, the DNA in the nucleoid may extend into the cytosol, or cellular fluid.
The nucleoid region may also contain proteins, enzymes (which are biological catalysts), and RNA. These proteins are necessary for several processes that take place in this region. For example, histones are proteins that assist with the coiling and packaging of DNA. Meanwhile, enzymes, such as topoisomerase, will help with replication, or copying, of DNA. These components assist in the growth and development of the cell through maintaining and facilitating these and other cellular processes.
The nucleoid region is the irregularly-shaped section of a prokaryotic cell where DNA is housed. It lacks the membrane that is found around the nucleus of eukaryotic cells. In addition to DNA, the nucleoid may also contain RNA, proteins, and enzymes that can be used for cellular processes.
After you’ve reviewed this video lesson, you should be able to:
- Differentiate between eukaryotic and prokaryotic cell structure
- Describe the nucleoid’s shape and function
- Identify structures found inside the nucleoid region