Table 1.
Comparison of cellular and non-cellular entities—cells possess each of these four significant genetic and structural materials
![]() |
In the case of viruses and subviral elements, only reduced suites of these key molecules are present. Since non-cellular entities can possess either DNA or non-DNA genomes and may lack lipids, the search for extraterrestrial DNA, RNA or lipid alone would fail to detect some of these entities.