Question

Explain progenote. (Topic:Evolution)

Answer 1

It is the common ancestor of all the living beings.
or
 The most recent common ancestor to all organisms now living on Earth.

Answer 2

Progenate is the term used to decsribe the hypothetical stage in the evolution of cells.It is the pre-prokaryotic stage of cellular organisation.At progenote level the genes and the encoded proteins were smaller and the transcription and translation accuracy is also less. Hence the sequence of evolution occured rapidly.


The current literature uses the term progenote in two different ways: It either signifies an organizational level that preceded cells with prokaryotic organization, or it is used to denote the last common ancestor of all extant life. In some scenarios describing early cellular evolution the last common ancestor was assumed to have been at a pre-prokaryotic level of organization; however, subsequent analyses of the molecular evolution of different cellular components suggest that the last common ancestor was a prokaryote. With this realization, the term progenote more properly should be used to denote a hypothetical pre-prokaryotic stage in cellular evolution, distinct from the last common ancestor.

          In 1977 Woese and Fox (1) defined the progenote as a hypothetical stage in the evolution of cells that preceded organisms with typical prokaryotic cellular organization: "Eucaryotes did arise from procaryotes, but only in the sense that the procaryotic is an organizational, not a phylogenetic distinction. In analogous fashion procaryotes arose from simpler entities. The latter are properly called progenotes, because they are still in the process of evolving the relationship between genotype and phenotype." The intention of Woese and Fox was to define an organizational level simpler than and preceding the prokaryotic level. At the progenotic level, genes and encoded proteins were smaller and the accuracy of transcription and translation was lower than at the prokaryotic level. As a result sequence evolution occurred more rapidly.

          At the prokaryotic level organisms contain a genome which encodes a multitude of biochemical and structural functions. Among the genome encoded functions present at the prokaryotic level are genome replication, translation of genomic information into functioning molecules, and formation of a semi-permeable barrier between the organism and its environment. Prokaryotic organization is so complex that the likelihood for the spontaneous assembly of a prokaryote from activated nucleotide and amino acid precursors present in a primordial soup is close to zero. A solution to this problem is to assume intermediate steps, which successively evolve into more complex structures. A usually assumed intermediate step in the origin of life are self-replicting RNA-like molecules. However, because of the limited accuracy of these early replicators, the size and information contained in these self-replicating molecules is limited .