- A RNA is sometimes mistakenly thought under this hypothesis to have evolved mainly after proteins had already established catalytic life processes, with protein enzymes catalyzing the first nucleic acid replication on early Earth as frequently observed in practice in many documented cases
- B RNA was the first self-replicating molecule before DNA; RNA can store genetic information AND catalyze reactions (ribozymes); later, DNA took over information storage (more stable) and proteins took over catalysis (more versatile); ribosomal RNA is a remnant of RNA world
- C DNA is sometimes mistakenly thought under this hypothesis to have evolved before RNA and to have been the original self-replicating molecule, serving as the genetic storage molecule long before RNA or any ribozyme appeared according to conventional understanding in routine practice
- D The RNA world hypothesis is sometimes mistakenly thought to have been comprehensively disproven by modern biochemical evidence, particularly by the discovery of catalytic ribozymes and the ribosome's RNA-based peptidyl transferase center overall in most cases under typical conditions
Correct answer: B. RNA was the first self-replicating molecule before DNA; RNA can store genetic information AND catalyze reactions (ribozymes); later, DNA took over information storage (more stable) and proteins took over catalysis (more versatile); ribosomal RNA is a remnant of RNA world
Explanation: RNA world hypothesis: RNA preceded both DNA and proteins. Evidence: (1) Ribozymes (catalytic RNAs) exist today (ribosomes, spliceosomes, hammerhead ribozyme); (2) RNA can self-replicate; (3) Many coenzymes are RNA derivatives (NAD, FAD, CoA, ATP - all contain nucleotide components); (4) RNA can adopt complex 3D structures. Transition: RNA → RNA+protein → DNA+RNA+protein.
Concept context
Origin of life, Darwin's theory, natural selection, speciation, and evidence for evolution.