In this article we will discuss about the evolution of exon structure. Average cellular gene is vertebrates contains about eight exons and detail analysis of human gene has yielded a classification scheme for exons according to their transcriptional or translational boundaries. According to this scheme there are 12 different categories which are: (i) 5' terminal un-translated exons. (ii) 3' terminal [...]
In this article we will discuss about the presence of DNA in mitochondria and chloroplasts. The presence of organelle-specific DNA in mitochondria and chloroplasts was identified with certainty over three decades ago. The occurrence of a specific chloroplast DNA was first demonstrated by Chun et al. in 1963, and of mitochondrial DNA a year later by Luck and Reich (1964). [...]
Some investigators of 1950s focused their attention on viruses containing protein and RNA, but no DNA. The poliomyelitis virus, influenza virus and the virus that causes mosaic disease in tobacco plants (TMV) were thus shown to have genes made of RNA. Earlier in 1935 W. M. Stanley had reported the isolation of a crystalline protein from infected tobacco plants, which [...]