The following points highlight the top two models of chromosomes. The models are: 1. Multiple Strand Models 2. Single Strand Models. Model # 1. Multiple Strand Models: a) Simple Multi-Stranded Model: According to this model the chromosome consists of 64 double helices of DNA arranged in a parallel number, and twisted together like the strands of a rope. The difficulty [...]
In this article we will discuss about the regulation of levels of transcription by DNA methylation. In most higher plants and animals, the DNA is often modified after synthesis by the enzymatic conversion of many cytosine bases to 5-methylcytosine bases (Fig. 5.8). The extent of methylation varies from species to species; in mammals, from 2 to 7 percent of the [...]
In this article we will discuss about:- 1. Background of Chromosomes 2. Location of Chromosomes 3. Number 4. Shape 5. Size 6. Chemistry 7. Chemical Components 8. Physiology. Historical Background of Chromosomes: i) The term chromosome (Gr. chromo, color; soma, body), when used by Waldeyer in 1888, represented the darkly stained individualized bodies located in the nucleus. ii) Walter S. [...]