Living systems share many characteristics. One of the most basic is the need to store
and use genetic information, the instructions that direct life processes.
Within living systems, genetic information guides the production of proteins, which are
the specialized machines that make organisms work. Living systems also must copy their
genetic information and pass a complete set on to their offspring. This process is called
replication.
Energy
Living systems need energy to interpret and replicate their genetic information. Outside
a living system, the energy requirements for completing biochemical reactions are very high.
Living systems get a break, however. They rely on biological catalysts, such as enzymes, to
lower energy requirements and carry out reactions quickly and accurately.
Why can living systems use catalysts to carry out biological reactions? One reason is that
living systems are self-contained, with a wall separating "inside" from "outside." On the
inside, a living system can generate and maintain optimal conditions for biochemical reactions.
On the outside, those conditions are difficult to achieve.
Catalysis
Inside a living system, biological catalysts reduce the energy needed for a reaction.
Catalysts can bring reactants close together or align them correctly to help the reaction take place.
The best-known catalysts are enzyme proteins, which are the workhorses of cells. Each enzyme plays
a specialized role in the workings of a living system. We now know the identities of many enzymes
that catalyze important biochemical reactions. In many cases, we also know which genes encode these enzymes.
How do catalysts work?
Try your hand at uncatalyzed and catalyzed reactions:
