MACRONUCLEUS Meaning and
Definition
-
A macronucleus refers to a distinct, larger nucleus found within ciliated protozoans, particularly those of the class Ciliata. In these organisms, the macronucleus serves as the primary nucleus responsible for coordinating cellular functions and genetic expression, while the smaller micronucleus, present alongside it, plays a role in genetic exchange during reproduction.
Structurally, the macronucleus exhibits a more prominent size, shape, and complexity compared to the micronucleus. It contains multiple copies of individual chromosomes, each being amplified and fragmented into smaller gene-sized pieces called macronuclear DNA molecules. These molecules are responsible for the direct regulation and synthesis of RNA transcripts involved in protein synthesis, metabolic processes, and cellular activities.
The macronucleus functions as the main control center of the cell, regulating essential life processes, such as cell division, growth, locomotion, and responses to environmental stimuli. It actively coordinates the expression of genes required for daily cellular functions, serving as a repository for genetic information solely utilized in nonsexual reproduction and maintaining cellular homeostasis.
The macronucleus undergoes a complex process of development and differentiation during the life cycle of a ciliate. It replicates and divides by amitosis, a form of nuclear division occurring independently of cell division. This allows the ciliate to sustain its genetic makeup and propagate the essential genes involved in cell functioning.
In summary, the macronucleus is a specialized nucleus found in ciliated protozoans, responsible for the regulation and expression of genes required for day-to-day cellular activities and maintaining cellular homeostasis.
-
The larger of the two nuclei in infusoria; it governs the vegetative metabolic functions, and has nothing to do with reproduction; trophonucleus, somaticnucleus.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
Common Misspellings for MACRONUCLEUS
- nacronucleus
- kacronucleus
- jacronucleus
- mzcronucleus
- mscronucleus
- mwcronucleus
- mqcronucleus
- maxronucleus
- mavronucleus
- mafronucleus
- madronucleus
- maceonucleus
- macdonucleus
- macfonucleus
- mactonucleus
- mac5onucleus
- mac4onucleus
- macrinucleus
- macrknucleus
- macrlnucleus
Etymology of MACRONUCLEUS
The word "macronucleus" is derived from two components: "macro-" and "nucleus".
The prefix "macro-" comes from the Greek word "makros", meaning "large" or "long". It is often used in English to denote something as "large-scale" or "big".
The term "nucleus" is from the Latin word "nuculeus", which refers to "nut" or "kernel". In biological terms, the nucleus is the central part of a cell that contains genetic material, regulating cellular processes.
Putting these components together, "macronucleus" refers to a larger-sized nucleus in certain organisms. It is a prominent feature found in ciliates, such as Paramecium, a unicellular organism, wherein the macronucleus controls most of the regular cellular activities.
Similar spelling words for MACRONUCLEUS
Infographic
Add the infographic to your website:
