Final answer:
The statement regarding TPP riboswitches and ribosome binding site creation is false. TPP riboswitches control gene expression by changing mRNA conformation when TPP is present, which may affect transcription or translation but does not create a ribosome binding site.
Step-by-step explanation:
The statement 'The TPP riboswitch folding creates a binding site for the ribosome only when bound to thiamine pyrophosphate' is false. TPP riboswitches are regulatory elements found in the 5' untranslated regions (UTRs) of mRNAs, particularly in bacteria, and they bind to the vitamin thiamine pyrophosphate (TPP). When TPP binds to a TPP riboswitch, it induces a conformational change in the mRNA that most often results in the regulation of gene expression, affecting transcription or translation.
However, this does not involve the creation of a ribosome binding site. Instead, it may prevent ribosome binding or alter the mRNA stability. For example, when TPP is abundant, the riboswitch may form a structure that prematurely terminates transcription or prevents ribosome access, thereby reducing the expression of genes involved in thiamine biosynthesis or transport.