Pentasomy (French : pentasomie) State of a cell or individual that has five copies of a chromosome instead of two. Example : the 49 XXXXX syndrome.
(French : replication d'ADN) The use of existing DNA as a template for the synthesis of new DNA strands. In humans and other eukaryotes, replication occurs in the cell nucleus.
[The origin of the eukaryotic cell
I will try to base my research on the origin of mitochondria based on a model that sees evolution as an expanding system of functional modules that communicate through strictly defined interfaces. In such a system that grows by functional extensions, existing interfaces cannot be changed anymore because of the dependencies of downstream functions on this interface. By analyzing the functional modules, their conserved interfaces and its dependants, it then becomes possible to determine the logical sequence of events that occurred in evolution. I will look specifically to genetic control, protein import mechanisms, metabolic function and its relation with the cell cycle. I believe that these subsystems that are involved in the origin of mitochondria point to a eukaryotic origin as a functional extension of the endomembrane system.
There are two basic types of cells: prokaryotic and eukaryotic
It is also claimed that phylogenetic evidence firmly supports the endosymbiotic theory, for instance by showing relatedness between mitochondria and specific groups of bacteria. Some mitochondrial proteins show indeed a similarity with specific bacterial proteins, both at the structural and at the gene level. However, this does not show that mitochondria are derived from bacteria, but only that these proteins have a common descent. Next to an origin from bacteria, it can also be that these related proteins descended from a common ancestor, that only the genes were transferred or that bacteria picked up the genes from either the nucleus or the mitochondria. In general, large mitochondrial genomes contain a mix of presumed eukaryotic, archaeal and eubacterial genes, in contrast to what you expect if mitochondria are of eubacterial origin. Furthermore, a priori assumptions in phylogenetic analyses, such as long-branch attraction can bias phylogenetic tree analysis. This is illustrated by the amitochondriate organisms that can be either placed ancestral in the eukaryotic tree or derived, depending on whether you assume they once possessed mitochondria or not. Thus, as long as we do not have a clear picture of the last common ancestor and its relationship with eukaryotes, it will be difficult to interpret gene similarity as evidence for the endosymbiotic theory.
‘In the endosymbiont theory, the ancestor of the eukaryotic cell ..
Based on decades of accumulated evidence, the scientific community supports Margulis's ideas: endosymbiosis is the best explanation for the evolution of the eukaryotic cell.
Little Mito grew up in a one-room house in the Eukaryote family
Bacteria can take up DNA from their surroundings and have a limited ability to incorporate it into their own genome.
the endosymbiotic hypothesis is both mitochondria and chloroplast are arising from prior organelles and the nuclear genes provide some proteins that are very helpful to them both.