In this article we will discuss about the structure of cells in all living organisms. In 1965, Robert Hooke observed a section of cork under microscope; he saw numerous chambers similar to those of beehive. He called the individual chambers as Cells. But he, in fact, observed only the walls of actual cells as he was viewing dead cells. Subsequently, [...]
The following points highlight the top four models proposed for chromosome structure. The models are: 1. Molecular Model 2. Multi-Stranded Model or Polyneme Chromosome Model 3. General Chromosome Model 4. Folded Fibre Model. Chromosome Structure: Model # 1. Molecular Model: This model of chromosome structure was proposed by Taylor and coworkers in 1957, 1963 and is based on the semiconservative [...]
In this article we will discuss about the Structure of Bacterial Cell. Bacteria (sing. bacterium) are unicellular prokaryotic microorganisms which divide by binary fission. They do not possess nuclear membrane and the nucleus consists of a single chromosome of circular double-stranded DNA helix (Fig. 1.1). Flagella: These are long filamentous, cytoplasmic appendages, 12-30 μm in length, protruding through the cell [...]