Recapitulation is a bold and influential idea that is particularly associated with Ernst Haeckel though many other biologists also supported it in the nineteenth and early twentieth centuries. According to the theory of recapitulation, the stages of an organism’s development correspond to the species’ phylogenetic history- in a phrase, “ontogeny recapitulates phylogeny.” Each stage in development corresponds to (that is, [...]
In this article we will discuss about the mechanisms of regulation of transcription in higher eukaryotes. In E. coli, the RNA polymerase holoenzyme (with sigma factor) contains all the information needed to accurately initiate transcription given proper promoter signals (-35 recognition sequence plus -10 Pribnow box). However, RNA polymerase II of eukaryotes, which transcribes most of the protein- encoding nuclear [...]
In this article we will discuss about the intercellular communication in multicellular eukaryotes. In multicellular eukaryotes, the mechanisms that control cell division and cell growth are even more complex because a new dimension intercellular communication must play a major role. Each tissue within an organ and each organ within the body of an organism must grow to the proper size [...]