Levels of Organization in Living Matter: Molecular to Cellular
Molecular Level
It includes the molecules, formed by the group of atoms (bioelements). The organic molecules are referred to as biomolecules or immediate principles. These principles can be immediately divided into two categories: inorganic (water, minerals, ions, gases) and organic (carbohydrates, lipids, proteins, and nucleic acids).
At this level, we also group the macromolecules and viruses. The first result from the union of monomers (amino acids, nucleotides, etc.), and the second is the binding of proteins with nucleic acids.
The molecular level is formed by the molecules, which are defined as material units formed by the union, through chemical bonding of two or more atoms, such as an oxygen molecule (O2) or calcium carbonate (CaCO3). The molecules that make up living matter are referred to as biomolecules, or immediate principles, and an example is glucose (C6H12O6). Organic molecules are those consisting essentially of carbon atoms linked by covalent bonds. Once considered only to be synthesized by living beings, they have now been achieved by artificial synthesis of carbon compounds that never appear in living beings, for example, plastics. Therefore, in organic molecules, it is necessary to distinguish between biomolecules and non-biomolecules.
Within the molecular level, there are varying degrees of complexity:
- Macromolecules result from the union of many organic molecules in a polymer; each polymer unit is called a monomer. For example, starch (macromolecule) is a polymer of glucose (monomer). Proteins are macromolecules made up of polymers of amino acids, and nucleic acids are polymers of nucleotides.
- Supramolecular complexes are formed by several molecules. For example, the binding of carbohydrates and protein to give glycoproteins.
- Organelles comprise a supramolecular complex, and although they have some of their own, they cannot be considered as living beings, as they do not meet their nutritional characteristics, relationships, and reproduction. Inside the cell, there are several cellular organelles such as mitochondria, peroxisomes, endoplasmic reticulum, and so on.
Viruses are macromolecular complexes that consist of two types of macromolecules: proteins and nucleic acids and, in some cases, also lipids.
Levels of Biotic Organization
There are four levels of biotic organization that are unique to living things:
Cellular Level
This level includes the cells, which are units of living matter formed by a membrane and cytoplasm. There are two types of cells:
- Prokaryotic cells are those that lack the nuclear envelope and, therefore, genetic information is scattered in the cytoplasm, although condensed in a region called the nucleoid.
- Eukaryotic cells are those with the genetic information surrounded by a nuclear envelope, which isolates and protects it, and is the core.
Cells are the smallest parts of living matter that can exist free in the environment. The bodies composed of a single cell are called unicellular organisms, and must perform all vital functions.