1. Biomembranes are organized, sheetlike assemblies consisting mainly of proteins and lipids 1.1 The functions carried out by membranes are diverse and indispensable for life 1.1.1 Biomembranes give cells their individuality by separating them from the environment。 1.1.2 Biomembranes are highly selective permeability barriers with specific protein channels and pumps regulating the molecular and ionic compositions of the intracellular medium(transport across membranes)1. Biomembranes are organized, sheetlike assemblies consisting mainly of proteins and lipids 1.1 The functions carried out by membranes are diverse and indispensable for life. 1.1.1 Biomembranes give cells their individuality by separating them from the environment. 1.1.2 Biomembranes are highly selective permeability barriers with specific protein channels and pumps regulating the molecular and ionic compositions of the intracellular medium (transport across membranes)