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#endosymbiotic theory

3 public questions tagged with this topic.

Basic Evolution

Eukaryotic cells evolved by:

Endosymbiosis reflects key principle in quiz on section b solved pyqs, where evolutionary mechanisms shape genetic variation and adaptation. In this context, Endosymbiosis aligns with experimental and theoretical evidence from population genetics, behavioral ecology and molecular phylogeny. Textbooks like Campbell Biology, Futuyma Evolution and Hartl Principles illustrate supporting data. Understanding why Endosymbiosis fits helps integrate natural selection, environment.

Ref: Futuyma, Evolution, Drift and Speciation PYQs.

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Chemogeny & biogeny

Endosymbiotic theory was proposed by

Endosymbiotic theory explains origin of mitochondria and chloroplasts from engulfed aerobic bacteria and cyanobacteria respectively. Evidence includes double membranes, circular DNA, 70S ribosomes and division similar to bacteria. Lynn Margulis championed this in 1967 synthesizing cytological and molecular data, now supported by phylogenomics. The theory accounts for eukaryotic complexity via symbiotic mergers rather than gradual invagination. Attribution to Lynn Margulis reflects her influential articulation establishing symbiogenesis as major evolutionary mechanism. This concept integrates genetics, ecology and molecular evidence, frequently tested in NEET, GATE and CSIR-NET, highlighting links between genotype, phenotype and environment.

Ref: Alberts et al., Molecular Biology of the Cell, 6th ed., Chapter 1: Origin of Life.

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General Biology of Protists

Secondary endosymbiosis involves engulfment of

Secondary endosymbiosis occurs when a eukaryotic cell that already possesses primary plastid, such as red alga or green alga, is engulfed by another non-photosynthetic eukaryote, which then retains algal plastid as secondary plastid often enclosed by three or four membranes reflecting additional engulfment steps. This process explains plastid diversity outside Archaeplastida, including euglenids bearing green algal secondary plastids and stramenopiles, alveolates, haptophytes containing red algal plastids. Nucleomorph remnants and periplastidial compartments provide evidence distinguishing secondary from primary endosymbiotic acquisition of photosynthesis.

Ref: Archibald Trends Plant Sci 2007 secondary endosymbiosis alga engulfed eukaryote; Campbell Biology 12th ed., Chapter 28 Secondary plastids complex

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