Final answer:
The molecule that has 2 trp codons and is capable of forming stem-loop structures is tRNA.
Step-by-step explanation:
The subject of this question is Biology. The question is asking for an example of a molecule that has 2 trp codons and is capable of forming stem-loop structures. One such example is the tRNA molecule.
tRNA (transfer RNA) is a type of RNA molecule that carries amino acids to the ribosome during protein synthesis. It contains an anticodon loop that recognizes and pairs with the codon on mRNA. In the case of the trp codon (UGG), the corresponding tRNA molecule is capable of forming a stem-loop structure.
This stem-loop structure plays a role in the regulation of gene expression. When tryptophan levels are high, the trp codons in mRNA are recognized by the trp tRNA, leading to the formation of a terminator stem-loop and termination of transcription. However, when tryptophan levels are low, the trp tRNA stalls at region 1 of the mRNA, allowing an antiterminator stem-loop to form, and allowing transcription to proceed.