Q.24 Genes in two species that are derived from the same ancestral gene in their most
recent common ancestor are called
(A) analogs
(B) heterologs
(C) orthologs
(D) paralogs
Correct Answer: (C) orthologs
Genes derived from the same ancestral gene in two species through speciation are orthologs, as they diverge after populations split into separate species while retaining similar functions.
Option Analysis
Analogs refer to structures or genes with similar functions but no shared ancestry, arising from convergent evolution rather than common descent.
Heterologs describe genes between species that lack homology, often used for unrelated sequences with different origins and functions.
Orthologs are homologous genes separated by speciation from a common ancestor, typically conserving function, such as human and mouse hemoglobin genes.
Paralogs result from gene duplication within the same lineage, leading to related genes in one species that may diverge in function, like alpha and beta globins in humans.
Orthologs play a key role in evolutionary biology and genomics, especially for CSIR NET Life Sciences aspirants studying gene homology. These genes in two species trace back to the same ancestral gene in their most recent common ancestor, diverging through speciation events.
Core Concepts
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Orthologs maintain functional similarity across species, aiding phylogenetic analysis and functional annotation.
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Unlike paralogs from duplication, orthologs reflect vertical descent post-speciation.
Exam Relevance
CSIR NET questions test distinguishing orthologs from paralogs, analogs, and heterologs in molecular evolution contexts.
Practical Applications
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Genome annotation transfers knowledge between model organisms.
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Drug discovery compares orthologs for conserved targets.
