Most simple (early) life forms

In this lecture Kirsi Lehto (University of Turku, Finland) discusses the essential features of cellular life ; what is required for life, and what are the criteria of life. Nucleic acids, genetic code and its expression system are conserved and ubiquitous properties of all life forms, and therefore are assumed to be the most original functional units of life.
Molecular analysis of these structures gives suggestions of how they may have been involved in the early molecular evolution, and what functions they may have provided to the early (precellular) replicators.