Alberts et al. tells us that the sixth universal feature of all cells is that:
One requirement of a cell in order to reproduce itself is to obtain free energy from its environment. Free energy and other raw material drive the necessary synthetic reactions that a cell must undergo. In other words, free energy consumption is the basis of life. Cells, because they are dynamic chemical systems, do not function at a level of chemical equilibrium. When a cell is unable to obtain free energy, the cell moves toward chemical equilibrium, eventually leading to its inevitable death (Alberts et al. 2014).
Free energy is also required for other basic life processes, including the propagation of genetic information. In fact, a definite quantity of free energy that is required for the specification of one bit of information exists, and can be calculated when the definition of free energy is understood precisely. The basic idea is somewhat intuitive, however (Alberts et al. 2014).
Free energy consumption is essential, again, to ensure that the correct bonds are made, and that they are made to be extremely robust, in the case of molecules that must be held in their correct places on a preexisting DNA template, and connected to one another in a fixed relationship. This is how genetic information is specified. It is done in the form of a DNA sequence, as an example. Molecules that are in a swarm of objects that are endowed with thermal energy are captured, then arranged according to some specific order defined by a preexisting template, and then linked together in a relationship that is fixed. Essentially, to put it most simply, cells require free energy to be spent on the creation of order (Alberts et al. 2014).
In later chapters, it will be discussed how free energy is actually derived by animal cells from their environments. Essentially, it is done through chemical bonds in food molecules that the animals consume. For plants, free energy comes from the sunlight. However, the process is more complex than a few sentences can provide, so this topic will be one to return to later on. For now, keep in mind that free energy Is required by all cells in order to replicate their genetic information and to create their complex molecules conforming to set specifications (Alberts et al. 2014).
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