Why Is Plant Cells?

1750 Words Dec 8th, 2014 7 Pages
Why is it that plant cells are autotrophic whereas animal cells are not? The answer is simple; chloroplasts. These are green organelles that are the main site for photosynthesis in plant cells. They allow the plant to be known as the ‘producer’ in a food chain. Being such an essential part of the plant cell, the question arises, where exactly did they come from in the first place. Have they been a part of the plant cells since the beginning of time or did they evolve from some other species, and how are they able to carry out a process without which there would probably no life on earth.

Where did they come from?
Interestingly, like organisms chloroplasts have ancestors too. These are called “cyanobacteria”. Cyanobacteria are morphologically complex organisms which belong to the family of eubacteria, also known as ‘true bacteria’. Chloroplasts evolved from these organisms by the ‘endosymbiont hypothesis’ which is the same mechanism that explains how mitochondria evolved. According to this theory, chloroplasts were not just mere structures once, in fact they were individual organisms and that is the reason that they contain their own genome. Not only were they quite similar to cyanobacteria, they also had a close relationship with plants cells, an interaction known as a symbiotic relationship. One can wonder, what exactly happened to chloroplasts then? Why didn’t they remain an individual species? Over time, these ‘photosynthetic bacterial cells’ formed the chloroplasts…
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