The first cells

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The first cells: cell evolution.
All agencies that currently inhabit the Earth are related because we come from
ancestral cells emerged more than 3800 million years as a result of a slow evolutionary process of the organic molecules accumulated in the primeval oceans.
It is believed that the decisive moment in the origin of the cells was the appearance of a biological membrane.

• The
membrane separated the external environment of the internal environment, which favored the existence of a rudimentary metabolism that enabled the ancestral cells get the energy (via nutrition) and use it to reproduce and respond to environmental changes.

Because they originated in a sea of organic molecules, probably the first cells were bacteriaanaerobic fermentative heterotrophs able to obtain food and energy directly from their environment. But a situation like this is self-limited, and all these primitive creatures disappear when food stocks were getting, if not for those first cells evolved to give rise to cyanobacteria that developed its own mechanism of energy production: photosynthesis.
The release of oxygen resulting from photosynthesis reducing early atmosphere transformed into a new oxidizing atmosphere very similar to today. This oxygen was becoming, gradually, in a deadly poison for anaerobic organisms. Many of the existing cells so far desaperecieron, others took refuge in inaccessible areas to oxygen and have survived so far. Others, however, managed to adapt and learned to use in their metabolic reactions. Thus, primitive bacteria
heterotrophic aerobic dueron able to use atmospheric oxygen to obtain energy from organic nutrients through a chemical process called cellular respiration, which releases carbon dioxide as a residual productp.
Later, at least 2700 million years ago, eukaryotic
cells evolved from a symbiotic partnership between different prokaryotic bacterial cells with simpler organization, according to the endosymbiotic theory proposed by biologist Lynn Margulis.

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