Albert L. Lehninger Quotes

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

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."

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

As a result, there is an electrostatic attraction between the oxygen atom of one water molecule and the hydrogen of another (Fig. 2-lb), called a hydrogen bond.

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

Among the seminal discoveries in biology in the twentieth century were the chemical nature and the three-dimensional structure of the genetic material, deoxyribonucleic acid, DNA.

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

In thermodynamic terms, formation of the solution occurs with a fa vorable free-energy change: ΔG = ΔH - TΔS, where ΔH has a small positive value and TΔS a large positive value; thus ΔG is negative.

Cells of all kinds share certain structural features.

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

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

Water is a polar solvent. It readily dissolves most bio­ molecules, which are generally charged or polar com­ pounds (Table 2-2); compounds that dissolve easily in water are hydrophilic (Greek, "water-loving"). In contrast, nonpolar solvents such as chloroform and benzene are poor solvents for polar biomolecules but easily dis­ solve those that are hydrophobic-nonpolar molecules such as lipids and waxes.

The first living organisms on Earth doubtless arose in an aqueous environment, and the course of evolution has been shaped by the proper­ ties of the aqueous medium in which life began.

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

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