Mitochondria, the energy-generating organelles in eukaryotic cells, and chloroplasts in plant cells, evolved from free-living bacteria.
The ancestor of mitochondria was a proteobacterium that was engulfed by an Asgard archaean organism.
Descendants of this endosymbiotic union gave rise to animals, fungi, and plants.
Plants later acquired a photosynthesizing cyanobacterium, which became the chloroplast.
Over time, most genes of the endosymbiotic organelles were transferred to the nucleus, resulting in a more efficient arrangement.
Choices were made regarding gene retention, where archaean genes were preferred for information technology (cell replication), and bacterial genes were favored for operations and protein assembly.
Rajan Sankaranarayanan's group at CCMB in Hyderabad conducted studies on cellular processes in endosymbiotic relationships.
They focused on protein synthesis and compared animals and fungi with plants.
Plants, having undergone multiple gene sets during their evolution, adopted different strategies compared to animals and fungi.
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Proteins are composed of amino acids, and nature uses only left-handed amino acids due to the poisonous nature of the right-handed ones.
Left/Right-handed amino acids are the stereoisomers in which the amine group of the molecule exists in the left/right-hand side
Animals and fungi adapt their mitochondria to deal with this discrepancy.
Plants, however, segregate the two policing machineries for amino acid discrimination in the cytoplasm and mitochondria.
L (Left Handed) and D (Right Handed) Amino Acids
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