Albert L. Lehninger

"Organisms possess extraordinary attributes, properties that distinguish them from other collections of matter. What are these distinguishing features of living organisms?"

"Biochemistry asks how the remarkable properties of living organisms arise from the thousands of different biomolecules."

"Despite these common properties, and the fundamental unity of life they reveal, it is difficult to make generalizations about living organisms."

"The unity and diversity of organisms become apparent even at the cellular level."

"Cells of all kinds share certain structural features."

"The upper limit of cell size is probably set by the rate of diffusion of solute molecules in aqueous systems."

"The distinguishing characteristics of eukary­otes are the nucleus and a variety of membrane-enclosed organelles with specific functions."

"All living organisms fall into one of three large groups (domains) [Bacteria, Archeara, Eukarya] that define three branches of evolution from a common progenitor."

"We can consider cellular energy conversions—like all other energy conversions—in the context of the laws of thermodynamics."

"The current understanding that all organisms share a common evolutionary origin is based in part on this observed universality of chemical intermediates and transformations, often termed "biochemical unity."

"The chemistry of living organisms is organized around carbon, which accounts for more than half the dry weight of cells."

"Virtually every chemical reaction in a cell occurs at a significant rate only because of the presence of enzymes."