Nucleoid

Definition

The nucleoid is the irregularly-shaped region within a prokaryotic cell that contains most of the genetic material. Unlike a eukaryotic nucleus, it is not surrounded by a nuclear membrane.

5 Must Know Facts For Your Next Test

1. The nucleoid contains the cell's chromosome, usually a single circular DNA molecule.
2. It is not enclosed by a membrane, distinguishing it from the nucleus in eukaryotic cells.
3. Proteins associated with DNA within the nucleoid help in processes like replication and transcription.
4. The nucleoid can occupy up to half of the cell's volume depending on its stage in the life cycle.
5. Supercoiling helps compact the DNA within the nucleoid for efficient space utilization.

Review Questions

• What structure within prokaryotic cells contains most of their genetic material?
• How does the nucleoid differ from a eukaryotic nucleus?
• What role do proteins play within the nucleoid?

Related terms

Plasmid:

A small, circular DNA molecule found in prokaryotes that is separate from chromosomal DNA.

Ribosome:

A cellular structure responsible for protein synthesis.

Cytoplasm:

The gel-like substance inside cells where organelles are suspended and various cellular processes occur.