is a working draft and is subject to change.
Last revised 04/10/30 at 20:02
The essentials for simple life include:
||Obtaining resources to allow maintaining one's own form and preserving the distinction between oneself and the environment.|
||Propagating one's own form to successive generations.|
||A context in which the above takes place.|
Non-mobile life - viruses, algae, fungi, plants, etc., depend upon dynamics in the environment for bring sustenance into a usable relation with themselves.
Members of the simplest class of non-mobile life - non-binders - depend upon an adequate supply of usable sustenance being presented to them by changes in the environment. Wind, blood flow, tides, diurnal cycles, (and mobile life), etc., all bring these organisms and their necessary resources into contact. When sufficient supplies of resources are present, these entities replicate. Examples are plasmids and the simplest of viruses. "Para-life", such as plasmids, and some of the simplest viruses can only replicate when amino acids are present in sufficient proportion and quantity that the DNA strand can be copied. In these cases, the replication process itself is indistinguishable in fact and principle from the sensing process. They are one and the same. If conditions are right, replication takes place, otherwise not.
The next level of development - energy binders - include mechanisms for storing energy during periods of abundance for use during periods of scarcity. These higher level organisms store usable resources in a form suitable for use later. A rudimentary mechanism is required to redirect excess resources from form maintenance and growth into storage. This constitutes a forerunner of internal condition senses. Another rudimentary mechanism is required to direct growth towards sustenance sources. This constitutes a forerunner of external senses. The simplest of these is just the lack of a transport mechanism. Resources that are used locally will cause growth where food is plentiful, while inhibiting growth where it is scarce. A transport mechanism allows resources obtained at any interface to be redistributed throughout the organism. In this situation a dedicated sensing mechanism is required in order to change from overall growing in all directions to storing sustenance. For example, a plant needs a chemical sensor of some kind to enable it to determine that there is sufficient excess sugar to convert it to starch and to store that starch for later, as well as a sensor to enable it to determine the need to convert stored starch back to sugar in times of scarcity. In order to convert excess sugar to starch, it must be recognized that excess sugar is present. An internal "sugar level" sense is needed, as well as a control mechanism which responds to the sense by converting sugar to starch and starch to sugar as appropriate.
Energy binders require a sensing mechanism that enables them to detect when there is an abundance of usable materials in the environment so they can respond by storing excess materials in a form suitable for use later. Non-binders grow and replicate whenever conditions permit it. Energy binders store resources in times of plenty for use later. For non-binders the replication process can be hap-hazard and subject to interruption by a change in the resources available in the environment. With energy-binders, sufficient resources can be stored to enable replication to take place without interruption. This requires another internal sensing mechanism - with the ability to sense when sufficient resources have been stored to permit a full replication cycle. Resources can also be stored for use in times of scarcity. This requires an external sensing mechanism - to differentiate times of plenty from times of scarcity.
It is reasonable to infer that a sensing mechanism based upon chemistry would be easily adapted for sensing conditions immediately external to the organism. Following the example above, the most obvious one would be a food sensor, one that detects the presence of sugar in the environment. For sensors to be effective, they must operate effectors. In the simplest of cases, the sensor and the effector may be one simple mechanism. For example, a sugar receptor on the surface of a cell might, when bound to sugar, reconfigure to open a pore in the cell membrane, thus allowing more sugar molecules to pass into the cell. The sensor-effector, in the act of sensing, effects the response mechanism. Anything more complex than this requires some mechanism of communication between the sensor and the effector. For simple organisms this can be a cascade of chemical reactions. For more complex organisms, this can include specialized structures, for example nerve cells.
|Non-binders||grow and replicate only when conditions are favorable - die or remain dormant when conditions are not favorable.|
|Energy-binders||store resources when conditions are favorable - consume resources to maintain self when conditions are not favorable to storing - able to sense when conditions are appropriate for storing or converting. - able to sense the presence of "food"..|
Mobile life essentials
|This page was updated by Ralph Kenyon on 2009/11/16 at 21:33 and has been accessed 18328 times at 105 hits per month.|