ENDOSYMBIOTIC THEORY Meaning and
Definition
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The endosymbiotic theory is a scientific concept that proposes the symbiotic relationship between two distinct organisms, with one organism living inside the cells of the other. This theory specifically focuses on the origin and evolution of eukaryotic cells, which are complex cells that contain a nucleus and membrane-bound organelles.
According to the endosymbiotic theory, it is believed that certain organelles found in eukaryotic cells, such as mitochondria and chloroplasts, were once free-living prokaryotes (smaller, simpler cells without a nucleus). Over time, these primitive prokaryotes were engulfed by larger ancestral cells, establishing a mutualistic relationship.
Through this endosymbiotic event, the engulfed prokaryotes were advantageous to the host cell and eventually evolved into specialized organelles. For instance, mitochondria are thought to have originated from an ancestral aerobic bacterium that provided the host cell with energy in the form of adenosine triphosphate (ATP). Similarly, chloroplasts are suggested to have originated from an ancestral photosynthetic bacterium, contributing to the host cell's ability to carry out photosynthesis.
The endosymbiotic theory has been widely accepted within the scientific community due to various evidence, such as the similarities between organelles and free-living prokaryotes in terms of structure, replication, and genetic material. This theory provides a comprehensive explanation for the complex composition and functions of eukaryotic cells, shedding light on the evolutionary processes that have shaped the diversity of life on Earth.
Etymology of ENDOSYMBIOTIC THEORY
The word "endosymbiotic theory" is composed of two main components, "endo-" and "symbiotic".
The prefix "endo-" comes from the Greek word "endon", meaning "within" or "inside". It is often used in scientific terms to indicate something that is located or occurring within a particular structure or organism.
The term "symbiotic" is derived from the Greek word "symbiosis", which is a combination of "sym-" meaning "together" and "biosis" meaning "life". Symbiosis refers to a close and prolonged association between two different species living together, often benefiting both organisms involved.
