Exploring the Last Eukaryotic Common Ancestor (LECA), the theoretical ancestor of all modern eukaryotes, believed to have existed 2 billion years ago. LECA exhibited complex cellular structures like a nucleus, mitochondria, and the ability for sexual reproduction. The text delves into the evolutionary steps leading to LECA, including the protoeukaryotic phase and the acquisition of mitochondria, which were pivotal for the rise of complex eukaryotic life.
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LECA is a theoretical construct in evolutionary biology, denoting the most recent common ancestor from which all extant eukaryotes are derived
Cellular Complexity
LECA was a group of organisms with considerable cellular complexity, including a nucleus, centrioles, cilia, and mitochondria capable of aerobic respiration
Reproduction and Protective Mechanisms
LECA had the ability to reproduce sexually and form protective cysts with cell walls composed of chitin or cellulose
LECA had a sophisticated cellular architecture with compartmentalization, endosomal sorting proteins, and mechanisms for genetic recombination
Sexual reproduction, involving meiosis and syngamy, is thought to have evolved in LECA as a mechanism to counteract the effects of reactive oxygen species
The evolutionary importance of sex, particularly in DNA repair, suggests its fundamental role in the common ancestor of all eukaryotes
The syntrophic and phagotrophic models propose different sequences for the acquisition of eukaryotic characteristics in LECA
Researchers have debated the importance of mitochondria in providing energy for larger cell size in the evolution of eukaryotes
The protoeukaryotic phase involved the loss of the rigid cell wall, evolution of internal membrane-bound compartments, and endosymbiotic acquisition of mitochondria
This phase culminated in LECA, an entity with essential protein families for cellular compartmentalization and other sophisticated functions
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The ______ is a concept in evolutionary biology representing the ancestor from which all modern complex-celled organisms evolved.
Last Eukaryotic Common Ancestor (LECA)
01
All current eukaryotes, which have cells with a nucleus, are believed to have descended from a population that existed about ______ years ago.
2 billion
02
This ancient group of organisms likely possessed structures such as a ______, centrioles, and cilia.
nucleus
