Formation maturation, differentiation and aging chloroplast. Dissemination 64th
The chloroplasts that at one point of evolution, 3800 million years ago, were primitive free cells, are individually evolution was transmitted to the rest of the cells derived from them.
Reproduction of chloroplasts is bipartition and doubling its circular DNA which is different from the DNA of the eukaryotic cell that currently hosts. Result of this process, two chloroplasts are produced called undifferentiated proplasts are produced.
Proplast differentiation is performed depending on the environment of the cytoplasm of the cell that houses it. Due to the absence of gene silencing areas in a circular DNA, the expression of any gene responds to external stimuli received:
1. If there is exposure to light proplast evolves into chloroplast increasing in size and developing thylakoids that accumulate as seed form where carbohydrates were stored.
2. If there is no exposition to light proplast evolve into etiplasts which are a poorly differentiated intermediate evolutionary form. From there leucoplasts were originated in the roots and chromoplasts in some plant cells especially in the fruits.
Finally chloroplasts can reach senescence becoming gerontoplasts with carotenoid accumulation, acquiring a reddish yellow color, and entering an irreversible phase.
In conclusion we can say that in the chloroplast circular DNA are encrypted, not only the instructions in the formation of ribosomes and the biosynthesis of organic matter, but also the keys to differentiation or cell specialization and cell death in the following million years follow all existing cells.