In this article we will discuss about the structure and functions of nucleolus. Structure of Nucleolus: Estable and Sotelo (1951) described the structure of a nucleolus under the light microscope. According to them, nucleolus consists of a continuous coiled filament called the nucleolonema embedded in a homogenous matrix, the pars amorpha. The first description of nucleolar ultra structure was given [...]
The following points highlight the six main parts of a chromosome. The parts are: 1. Pellicle and Matrix 2. Chromatids, Chromonema and Chromomeres 3. Centromeres 4. Secondary Constriction 5. Satellite 6. Telomere. Part # 1. Pellicle and Matrix: A membrane which surrounds each chromosome is said as pellicle. A jelly substance present inside the membrane is called as matrix. Presumably [...]
In this article we will discuss about:- 1. Meaning of Chromosomes 2. Number of Chromosomes 3. Size 4. Chemical Composition 5. Functions 6. Special Types. Meaning of Chromosomes: Chromosomes are the most important constituents of the nucleus and were first observed by Holfmeister (1848) in pollen mother cell of Tradescantia and called it nuclear filaments. Chromosomes are filamentous bodies which [...]