Many researchers now believe that the first self-replicating molecules were __________.

• A. DNA
• B. phospholipids
• C. viruses
• D. true proteins
• E. RNA

Answer: (E)

Verified step by step guidance

1. Understand the concept of self-replicating molecules: Self-replicating molecules are those that can make copies of themselves without the need for other molecules. This is a key feature in the origin of life.
2. Explore the role of RNA in early life forms: RNA is believed to have been one of the first self-replicating molecules due to its ability to store genetic information and catalyze chemical reactions, a concept known as the 'RNA world hypothesis'.
3. Compare RNA with other options: DNA is a stable molecule for storing genetic information but requires proteins for replication. Phospholipids form cell membranes but do not store genetic information or replicate. Viruses require host cells to replicate, and true proteins do not store genetic information.
4. Consider the RNA world hypothesis: This hypothesis suggests that RNA could have been the precursor to both DNA and proteins, acting as both genetic material and a catalyst for biochemical reactions.
5. Conclude why RNA is the correct answer: Given its dual role in catalysis and genetic information storage, RNA is considered the most likely candidate for the first self-replicating molecules, supporting the idea that life could have started with RNA.