TAG: GS 3: SCIENCE AND TECHNOLOGY
THE CONTEXT: The recent discovery of a new organelle, termed nitroplast, reignites interest in the endosymbiotic theory, challenging traditional views on genetic inheritance and cellular evolution.
EXPLANATION:
- Rooted in Lynn Margulis’s theory of symbiogenesis, the endosymbiotic theory posits that organelles like mitochondria and chloroplasts originated from once free-living bacteria, later integrated into eukaryotic cells.
Discovery of Nitroplast: Evolutionary Implications
- Recent studies published in Science and Cell highlight the discovery of a new organelle, nitroplast, which evolved as a symbiotic cyanobacterium within marine algae.
- Nitroplast’s integration into the host cell’s architecture, protein importation from the host cell, synchronization with host cell growth, and inheritance during cell division satisfy key criteria for organelle status.
Revolutionary Implications in Agriculture
- The discovery of nitroplasts opens new avenues in agricultural biotechnology, particularly in addressing nitrogen deficiency in plants.
- While the Haber-Bosch method revolutionized agriculture by synthesizing ammonia-based fertilizers, it poses environmental challenges such as water and air pollution and contributes to climate change.
- Nitroplasts offer a sustainable alternative by enabling plants to fix nitrogen independently, potentially reducing reliance on industrial ammonia production.
Biotechnological Applications and Challenges
- The potential biotechnological applications of nitroplasts include engineering host cells and their nitroplasts with minimal genomes for efficient nitrogen fixation, introducing nitroplasts into plant cells to confer nitrogen-fixing capabilities, and organelle transformation to incorporate nitroplasts and their host genes.
- However, these applications pose significant challenges and are still in the realm of theoretical exploration.
| Nitrogen Fixation | |
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Nitrogen fixation is the process by which molecular nitrogen (N2), with a strong triple covalent bond, is converted into ammonia (NH3) or related nitrogenous compounds.
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All biological reactions of nitrogen fixation are catalyzed by nitrogenase enzymes, which contain iron and often a second metal like molybdenum or vanadium.
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Essential for the biosynthesis of all nitrogen-containing organic compounds including amino acids, proteins, and nucleic acids; crucial for agriculture and the manufacture of fertilizer.
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Performed naturally in soil by microorganisms called diazotrophs, which include bacteria like Azotobacter and archaea. Some have symbiotic relationships with plants, especially legumes.
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Occurs naturally through microorganisms in soil, in symbiotic relationships between bacteria and plants, among termite and fungi, and in the air by NOx production from lightning. |
Endosymbiotic theory:
- The endosymbiotic theory, also known as symbiogenesis, proposes that some organelles in eukaryotic cells, like mitochondria and chloroplasts, were once free-living prokaryotic microbes that formed a symbiotic relationship with host cells.
- This theory suggests that mitochondria and chloroplasts originated from prokaryotic organisms through a process of endosymbiosis, where one organism lives inside another.
- Evidence supporting this theory includes the similar size of mitochondria and chloroplasts to prokaryotic cells, their ability to divide by binary fission, the presence of circular DNA in these organelles, and the existence of ribosomes with 30S and 50S subunits.
- Additionally, the endosymbiotic theory is reinforced by the fact that mitochondria and chloroplasts have their own chromosomes, reproduce independently, and share similarities with bacteria in terms of their structure and function.