Ubiquitin is a tiny protein containing only 76 amino acids, yet it participates in an astonishing range of cellular activities. It helps determine which proteins are destroyed, which are moved, which signaling pathways are activated, how damaged DNA is repaired, whether inflammation begins or ends, when a cell divides, whether a damaged mitochondrion is eliminated, and sometimes whether the cell itself survives or dies. How can the same tiny molecule mean so many different th

Water is the medium that makes life possible. Water is so ordinary that we rarely think of it as doing anything. But inside a living cell, water is not a passive background—it is an active participant in nearly every molecular event and every cellular structure. The water molecule has a peculiar geometry. One oxygen atom pulls so strongly on two hydrogen atoms that it ends up slightly negative, while the two hydrogens are left slightly positive, which results in four partial