X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/chloroplast13.git/blobdiff_plain/9d33c5f06454db8d752fa7bbe08f9bdaa3977b1a..9771923779498f5cbf4e21e9389062ac5d5cbb11:/intro.tex?ds=inline

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@@ -4,4 +4,23 @@ build a genes  content evolutionary tree. More precisely,  we focus on
 the following  questions considering a  collection of 99~chloroplasts
 annotated from NCBI \cite{Sayers01012011} and Dogma \cite{RDogma}: how
 can  we identify the  best core  genome and  what is  the evolutionary
-scenario of these chloroplasts.
+scenario of these chloroplasts.\\
+Chloroplast (such as mitochondria) are fondamental key elements in 
+living organisms history. Indeed, chlorplast in Eucaryotes are organites responsible for 
+photosynthesis. Photosynthesis is the main way to produce organic matter 
+from mineral matter, using solar energy. Consequently photosynthetic 
+organisms are at the base of most ecosystems trophic chains and 
+photosynthesis in eucaryotes allowed a great speciation in the lineage 
+(to a great biodiversity). From an ecological point of view, 
+photosynthetic organisms are at the origin of the presence of dioxygen 
+in the atmosphere (allowing extant life) and are the main source of mid- 
+to long term carbon stockage (using atmospheric CO2, important in the 
+context of climate change). Chloroplast found in Eucaryots have an endosymbiotic origin, meaning 
+that they are a fusion of a photosynthetic bacteria (Cyanobacteria) and 
+a eucaryotic cell (enable to produce organic matter from solar energy = heterotrophic). \\
+
+By  the  principle  of
+classification, a  small number of genes lost  among species indicates
+that these species are close to  each other and belong to same family,
+while a  large lost  means that we  have an  evolutionary relationship
+between species  from different families.