Note4Students
From UPSC perspective, the following things are important :
Prelims level: Obelisks, Viroids
Mains level: NA
In the news
- Recently identified by scientists at Stanford University, obelisks represent a distinct class of virus-like entities residing within the human body.
What are Obelisks?
- Novel Discoveries: Recently identified, obelisks represent a distinct class of virus-like entities residing within the human body.
- Genetic Diversity: Comprising diverse RNA molecules, obelisks have pervaded both human and global microbiomes, yet remained unnoticed until now.
- Distinctive Characteristics:
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- Structural Symmetry: Named after the rod-like, highly symmetrical structures formed by their twisted RNA strands.
- Genetic Makeup: Obelisks boast compact genetic sequences of approximately 1,000 nucleotides, devoid of known similarities to other biological agents.
- Size Disparity: Significantly larger than conventional genetic molecules like plasmids, which are primarily composed of DNA.
- Taxonomic Position: Positioned between viruses and viroids, obelisks constitute a unique class of organisms with intriguing properties.
- Host Interaction: While the hosts of certain obelisks remain unidentified, bacterial associations are speculated, hinting at a broader ecological significance.
- Spatial Distribution: Various types of obelisks inhabit diverse regions within the human body, highlighting their pervasive presence and potential physiological roles.
Understanding Viroids: Nature’s Tiny RNA Loops
- Genetic Cousins: Viroids are compact loops of RNA, closely related to DNA, primarily infecting plant organisms.
- Discovery: In 1971, Theodor Diener identified viroids during research on potato spindle tuber disease, revealing naked RNA entities devoid of protein coats or lipid layers.
- Unique Features:
- Lack of Encapsulation: Unlike larger RNA viruses, viroids lack protective shells, relying solely on their RNA structure for stability.
- Genetic Composition: Viroid RNA does not encode protein-building instructions, contrasting with viruses that carry genetic blueprints for their replication machinery.
- Host Interactions: Viroids exploit host enzymes for replication, highlighting their parasitic nature within plant cells.
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