Practice question · Put in order
Place these stages of early molecular evolution in the order the RNA world hypothesis proposes.
- DNA takes over information storage from RNA
- RNA molecules appear that both store information and catalyse reactions
- RNA begins directing the synthesis of proteins
- Simple organic molecules form and accumulate
Hints
- The hypothesis starts before any polymer capable of both roles.
- DNA arrives last, taking over storage because it is chemically more stable.
Show the answer
- Simple organic molecules form and accumulate
- RNA molecules appear that both store information and catalyse reactions
- RNA begins directing the synthesis of proteins
- DNA takes over information storage from RNA
Why
The sequence runs from prebiotic chemistry to a self-sufficient RNA world, then to RNA-directed protein synthesis, and finally to DNA taking over storage. Each step is a division of labour that improves on the one before.
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More questions on The Origin of Life and the RNA World
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