The Nucleus was derived by Robert Brown in 1831, just after the discovering of cell. It was said that the cell is an empty hollow space so therefore Robert Brown studied it further and said that it isn’t hollow space, but it contains a spherical or oval in shaped membranous organism, it the center of cell (Central Body of the Cell).
After the complete research it was said that it is the control room of cell because it controls all the activities of cell by producing enzymes, which are directed by mRNA (Copy made form DNA). Also, it is in the center only in animal cell but in plan cell it is slightly near of the cell wall because of large vacuole.
Structurally nucleus contains following:
- Nuclear Membrane
- Nuclear Pores
- Nucleoplasm or Karyolymph
- Nucleolus
- Chromatin Network
Also Read: Cell theory and Types of Cell
Also Read: Eukaryotic Cell
Nucleolus: (Small center in the nucleus)
It is a center within center ((Central Body of the Cell)). Nucleolus is responsible for RNA production and ribosomes. It contains network combines at the time of Cell Division and forms Chromosomes. The chromosomes are fixed in numbers in each species.
Numbers of Chromosomes in different species (which are fixed)
|
Species |
Number of Chromosomes |
|
Man |
46 |
|
Frog |
26 |
|
Chimpanzee |
48 |
|
Drosophila (fruit fly) |
08 |
|
Onion |
16 |
|
Potato |
48 |
|
Garden Pea |
14 |
The Chromosomes are composed of Chromatids and Centromere.
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Chromosomes
Chromosomes contains the hereditary units called as genes, which carries the hereditary information in all generations. These are elongated structured and visible only during cell division, typically the chromosomes are consisting of two parts one is arm and other is centromere.
The two chromatids joint together by centromere and form a chromosome.
Visit here for more study of Nucleus, Ribosomes & Vacuoles
Chromosomes are of different types but depending upon the centromere positions.
- Metacentric: In which the centromere is in the middle.
- Submetacentric: When the centromere is in the half of the middle.
- Sub telocentric: When centromere is in some distance form the end.
- Telocentric: When centromere is completely at the end.
, and the chromosomes (the hereditary units called as genes) and the types of Chromosomes.){kind=link}