Macronucleus
Macronucleus
Macronucleus (/mækroʊˈnjuːkliəs/; from the Greek makros, meaning "large", and karyon, meaning "kernel") is a type of nucleus that is found in ciliates, a group of single-celled protozoans.
Definition
The macronucleus is the larger of the two types of nuclei in ciliates, the other being the micronucleus. It is involved in controlling the non-reproductive cell functions, such as metabolism and growth. The macronucleus is polyploid, meaning it contains multiple copies of each gene.
Function
The macronucleus controls the everyday functions of the cell, while the micronucleus is reserved for sexual reproduction. During the sexual reproduction process, known as conjugation, the micronucleus undergoes meiosis and the macronucleus disintegrates. After conjugation, a new macronucleus forms from the micronucleus.
Structure
The macronucleus is typically oval or kidney-shaped, but its shape can vary depending on the species of ciliate. It contains a large amount of DNA, which is organized into chromosomes.
Related Terms
- Micronucleus: The smaller nucleus in ciliates, involved in sexual reproduction.
- Ciliate: A group of single-celled protozoans that possess cilia, or hair-like appendages.
- Protozoa: A diverse group of unicellular eukaryotic organisms.
- Conjugation (biology): A type of sexual reproduction in single-celled organisms.
- Nucleus (cell): The membrane-bound organelle that contains the cell's chromosomes.
External links
- Medical encyclopedia article on Macronucleus
- Wikipedia's article - Macronucleus
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