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Related Concept Videos

Eukaryotic Evolution01:24

Eukaryotic Evolution

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The endosymbiont theory is the most widely accepted theory of eukaryotic evolution; however, its progression is still somewhat debated. According to the nucleus-first hypothesis, the ancestral prokaryote first evolved a membrane to enclose DNA and form the nucleus. Conversely, the mitochondria-first hypothesis suggests that the nucleus was formed after endosymbiosis of mitochondria.
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Once a ligand binds to a receptor, the signal is transmitted through the membrane and into the cytoplasm. The continuation of a signal in this manner is called signal transduction. Signal transduction only occurs with cell-surface receptors, which cannot interact with most components of the cell, such as DNA. Only internal receptors can interact directly with DNA in the nucleus to initiate protein synthesis. When a ligand binds to its receptor, conformational changes occur that affect the...
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The Tree of Life - Bacteria, Archaea, Eukaryotes02:40

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The “tree of life” describes the evolution of life and the evolutionary relationships between organisms. The root of the tree is the common ancestor to all life on Earth. All other species radiate from this point, much like the branches of a tree. The numerous tips of these branches on the tree of life represent every living, or extant, species. Extinct species, which are species that no longer exist, can be found towards the center of the tree. Currently, these organisms, both...
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Cellular respiration is a fundamental metabolic process that enables organisms to generate energy from organic molecules. One of its central pathways is the tricarboxylic acid (TCA) cycle, also known as the Krebs cycle, which plays a crucial role in energy production and biosynthetic processes.Conversion of Pyruvate to Acetyl-CoAThe pyruvate generated from glycolysis undergoes oxidative decarboxylation by the pyruvate dehydrogenase complex, producing acetyl-CoA, one molecule of NADH, and one...
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Diversity in Cell Signaling Responses01:22

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The physiological function of a cell and cellular communication are outcomes of a range of extrinsic signals, intracellular signaling pathways, and cellular responses. No two cell types express the same repertoire of signaling components. Receptors are highly selective for their cognate ligands, but once activated, they can alter multiple cellular processes such as DNA transcription, protein synthesis, and metabolic activity. 
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The Citric Acid Cycle: Output01:28

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The citric acid cycle is termed an amphibolic pathway as it operates both anabolically and catabolically. The cyclic reactions balance the flux of the substrates to provide an optimal concentration of NADH and ATP to the cell.
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TCA cycle signalling and the evolution of eukaryotes.

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Mitochondrial signaling, not just genomes, drove eukaryotic evolution. The tricarboxylic acid (TCA) cycle regulated gene expression and histone modifications, enabling complex cell development.

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Area of Science:

  • Evolutionary Biology
  • Cellular Biology
  • Genomics

Background:

  • The origin of eukaryotic complexity from prokaryotic ancestors remains a key question.
  • Endosymbiont theory posits mitochondria arose from an archaeal host and an α-proteobacterium.
  • Mitochondrial genomes and archaeal histones are considered crucial for eukaryogenesis.

Purpose of the Study:

  • To propose a new evolutionary concept for eukaryogenesis.
  • To highlight the role of mitochondrial tricarboxylic acid (TCA) cycle signaling in regulating genome expansion and complexity.
  • To explore TCA cycle remodelling as a conserved eukaryotic strategy for stress response and gene expression.

Main Methods:

  • Conceptual evolutionary analysis.
  • Review of existing literature on endosymbiosis, mitochondrial function, and gene regulation.
  • Focus on the metabolic connections between the TCA cycle and epigenetic modifications.

Main Results:

  • Mitochondrial TCA cycle signaling is proposed as a critical factor in eukaryogenesis.
  • TCA cycle metabolites can dynamically control genome expansion via DNA and histone modifications.
  • TCA cycle remodelling is a common strategy in eukaryotes for coordinating stress responses and gene expression.

Conclusions:

  • Mitochondrial metabolic signaling played a vital role in the evolution of complex eukaryotic cells.
  • The TCA cycle and its metabolites, like itaconate, are key regulators of gene expression and cellular adaptation.
  • Understanding TCA cycle dynamics offers insights into fundamental eukaryotic evolutionary processes.