Everything in biology and the body depends on proteins.

This is a broad scientific generalisation made in popular explanation; 'everything' is read as 'virtually all biological processes'. TRUE: standard biology references show that proteins are needed for essentially all cellular and bodily functions (structure, catalysis, transport, signalling, replication, gene expression), and that exceptions such as catalytic RNAs still operate within protein-dependent systems. MOSTLY TRUE: proteins are central to almost all processes, but a few recognised processes or entities run largely without proteins (for example, some ribozyme activity, or viroids' replication strategy), and the claim slightly overstates. MIXED: significant categories of biological function are shown not to depend on proteins. MOSTLY FALSE: proteins are important, but large parts of biology are shown to be protein-independent, so the claim is a significant overstatement. FALSE: the evidence shows that most biological processes do not depend on proteins.

Set before the research began.

1. E1 Proteins NCBI Bookshelf (Alberts B, Johnson A, Lewis J, et al., Molecular Biology of the Cell, 4th edition, Garland Science) · 2002

   “They are not only the building blocks from which cells are built; they also execute nearly all cell functions.”

2. E2 Peptide bond formation by in vitro selected ribozymes - Nature Nature (Zhang B, Cech T.) · 4 November 1997

   “Here we demonstrate the in vitro selection of ribozymes (196 nucleotides) that perform the same peptidyl transferase reaction as the ribosome: that is, they can join amino acids by a peptide bond.”

3. E3 Viroids International Committee on Taxonomy of Viruses (ICTV), Ninth Report · 2009

   “Viroids are small, circular, single stranded, non-protein-coding RNAs that replicate autonomously when inoculated into higher plants.”

4. E4 Viroids International Committee on Taxonomy of Viruses (ICTV), Ninth Report · 2009

   “in the family Pospiviroidae cleavage is catalyzed by host factors (probably one or more of the RNase III-like proteins)”

A standard molecular biology textbook says proteins build cells and carry out "nearly all cell functions" (E1). This supports the generalisation, though it says "nearly all" rather than "all". A peer-reviewed paper reports in vitro selected ribozymes that perform the same peptide-bond-forming reaction as the ribosome (E2). That is the kind of protein-independent ribozyme activity the criteria name as a slight overstatement. Viroids are non-protein-coding RNAs (E3), though in one viroid family a cleavage step is catalysed by host factors that are probably proteins (E4). On balance, proteins are central to almost all processes and the word "everything" slightly overstates, so the claim is mostly true.