In this article we will discuss about the structure of chromatin in the light of nucleosome. Preamble: A supercoil model for chromatin structure was originally described by Pardon and Wilkins in 1972. Later studies of Boldwin (1975), Kornberg (1974) and others have shown that such a sub-unit structure of chromatin is not only present in mammalian cells but also found [...]
In this article we will discuss about the structure of lac operon in E. coli. The lac operon comprises three structural genes (z, y & a) and produces a polycistronic mRNA (Lac mRNA). This messenger RNA codes for β-galactosidase, lac permease and transacetylase. The lac permease is a single unit protein that acts as a carrier for the entrance of [...]
In this article we will discuss about some of the important structural features of DNA. 1. DNA exists as a double helix in which the two polynucleotide chains are coiled about one another in a spiral with a diameter of about 20Å (Fig. 1). 2. Concentration of thymine was always equal to the concentration of adenine and the concentration of [...]