Question

What is serial endosymbiosis?

Answer 1

Hint: Endosymbiotic theory refers to a group of theories that regard various organelles in eukaryotic cells as descendants of endosymbionts, where an endosymbiont is a microbial cell that has established a long-term residence within another microbial cell as a host.

Complete answer:
According to Serial Endosymbiotic Theory, prokaryotic "symbiotic consortiums" were the ancestors of eukaryotic cells. Symbiosis is a term used in ecology to describe the coexistence of two distinct species, and examples of ‘economic' symbiotic relationships abound in nature. Endosymbiosis is a "topological arrangement," according to Margulis, in which a long-term symbiotic relationship creates an interdependent relationship in which the pieces form a new whole. As a result, endosymbiosis promotes evolutionary creativity by providing a survival advantage through metabolic cooperation. Endosymbiotic theory states that mitochondria and plastids were once free-living bacteria in their most basic and well-known forms. Mitochondria (eukaryotic cells' powerhouses) are made up of free-living proteobacteria. Cyanobacteria produce plastids (plant cells' chlorophyll-containing solar panels). The endosymbiotic theory is most often used to describe eukaryotic cell origins, but it can also be extended to bacterial cells. Gram-negative bacteria, for example, may have developed from an endosymbiotic relationship between a clostridium and an actinobacterium, meaning that their inner membrane is derived from the endosymbiotic bacterium's plasma membrane, whereas their outer membrane is derived from the bacterial host's plasma membrane.

Note:
In his theory of evolution, Darwin ignored the importance of symbiotic relationships. Furthermore, endosymbiotic fusion of evolutionarily distinct lineages (netlike or reticulate evolution) contradicts his concept of bifurcating separation from common ancestors (tree-like evolution).