In this article we will discuss about:- 1. Coiled DNA Model 2. Nucleosome-Solenoid Model of Chromatin Fibres. Coiled DNA Model: This model of chromatin structure was proposed by DuPraw in 1965. As per this model, DNA molecule is associated with three classes of proteins: (i) Lysine rich histories: They are common to both A and B type fibres and are [...]
The following points highlight the two main adaptational forms of chromosomes. The forms are: 1. Polytene Giant Chromosomes 2. Lampbrush Chromosomes. Form # 1. Polytene Giant Chromosomes: Polytene giant chromosomes are normal interphase chromosomes where homologues become paired and undergo several replications; all the copies so produced remain associated together. Polytene giant chromosomes are typically found in salivary gland cells [...]
In this article we will discuss about the molecular structure of centromere. Eukaryotic chromosomes possess a segregational device called centromere which is responsible for the chromosomc movement during cell division. Chromosome fragments without a centromere (acentric fragments) are unable to move to any of the poles during cell division; as a result, they are excluded from the daughter nuclei and [...]