Biology Reference
In-Depth Information
which enables them (or the zygote or egg cell in parthenogenetic organisms) to
develop the Bauplan up to an early embryonic stage known as the phylotypic
stage . At this stage, when the epigenetic information provided to gametes becomes
exhausted, the nervous system would have developed. It is the first organ system to
develop, and it serves the embryo as a primordial epigenetic programmer. From this
point in time, the embryo becomes developmentally self-sufficient. It generates the
epigenetic information necessary to control the further postphylotypic development
of the embryo into an adult organism.
Biological Information
The Spatial Arrangement of Cells Needs a New Kind
of Information
The reproduction of any biological system basically requires the following:
- Building blocks.
- Information on the spatiotemporal arrangement of the building blocks.
- Free energy for implementing that arrangement.
The building blocks of unicellulars are proteins and other molecules, supramo-
lecular structures, and organelles. In multicellulars, the cell is the universal building
block.
The cell structure in unicellulars, plants, and animals exhibits significant differ-
ences. Figure 2.1 shows a Paramecium as a representative of eukaryote unicellulars.
A generalized structure of the plant cell and animal cell is presented in Figure 2.2 .
The building blocks are the objects of special studies of cytology in unicellulars
and of cytology, histology, and anatomy in multicellulars. The use and transforma-
tion of the free energy in the metabolic processes of cells and multicellular organ-
isms is the object of study in biochemistry. Structure, metabolism, and biochemistry
are known in adequate detail. Hence, we are going to only review the essentials of
biological information responsible for the spatiotemporal arrangement of molecu-
lar structures, supramolecular structures, and organelles in unicellulars, and of bil-
lions or trillions of different types of cells in metazoans from which the breathtaking
diversity of forms in the animal kingdom arises.
The erection of animal structure, by any account, requires huge amounts of infor-
mation of various types, which in an all-embracing term we call biological informa-
tion . This information is not only used in the process of reproduction via individual
development but it also functions to maintain the structural, functional, and mor-
phological identity of species during the life of the animal. To avoid the confusion
that may stem from the present varying concepts of inheritance, we start with a nar-
row definition of biological inheritance: all structures, functions, behaviors, and life
histories derived from the parent. The definition remains purely biological in that it
ignores all extrabiological artifacts, such as the construction of nests, human mate-
rial, and spiritual culture, which have found a home in discussions of biological
inheritance.
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