Organic substances and compounds are chemical compounds that include carbon atoms. This includes proteins, carbohydrates, fats, nucleic acids, and other compounds that are not found in inanimate nature. Different types of cells may consist of various amounts of organic compounds. For example, plant cells contain more carbohydrates, and animal cells contain more proteins. As I can remember, a functional group is an active, easily changing atomic group with specific chemical properties, necessarily containing atoms of oxygen, nitrogen, sulfur, or other elements capable of forming polar bonds. Another characteristic of this class of organic compounds that determines its chemical properties is a structural fragment of a molecule. Examples of functional groups are hydroxyl, carbonyl, carboxyl, or amino groups (Brown & Poon, 2015). An organic substance molecule may contain not one, but several functional groups. If a molecule contains one or more identical functional groups, then these are compounds with homogeneous chemical functions. If a molecule has several different functional groups, such a substance is a compound with mixed chemical functions. The functional groups determine the overall property of a molecule, which plays a critical role in building such more complex molecules as proteins.
In my opinion, the most important difference between prokaryotes and eukaryotes is the presence of a nucleus in the latter, which is reflected in the name of these groups. Hence, prokaryotes are pre-nuclear organisms, and eukaryotes are nuclear. However, this is far from the only difference between prokaryotic organisms and eukaryotes. There is no membrane organelles in the cells of prokaryotes, such as mitochondria, chloroplasts, Golgi complex, endoplasmic reticulum, and lysosomes. Their functions are performed by outgrowths or invaginations of the cell membrane, on which various pigments and enzymes are located, which ensure vital processes. Prokaryotes have no chromosomes characteristic of eukaryotes, and their main genetic material is a nucleoid, usually in the form of a ring. In eukaryotic cells, chromosomes are complexes of DNA and histone proteins that play an important role in DNA packaging. These chemical complexes are called chromatin, while the prokaryote nucleoid does not contain histones, and the RNA molecules associated with it give the form.
Plant and animal cells are both eukaryotic life forms with key differences. As I recall, plant cells possess cell walls made from cellulose, whereas animal cells’ outer layer is a plasma membrane. Plant cells also have plastids, which capture the light energy and convert it into an organic one. Therefore, animal cells’ feeding metabolism is heterotrophic, but it is autotrophic in plants. The latter usually contains one large vacuole without any specialization, whereas animal cells have different variations of the given structure.
As far as I know, mitochondria, similarly to plastids, are double-layered organelles, which most likely originated in ancient prokaryotic life forms. Mitochondria are covered by two layers, such as a smooth outer membrane and a folded inner one, where the latter has a large surface. The folds of the inner membrane deeply penetrate the matrix of mitochondria, forming a transverse septum called crista. The area between the outer and inner layers is usually called the intermembrane space. According to endosymbiosis theory, both mitochondria and plastids were separate prokaryotic organisms, which were engulfed and became a part of the endosymbiosis relationship with a larger host cell (Archibald, 2015). The given hypothesis is supported by the fact that mitochondria possess its own DNA and ribosomes. The organelle allows a cell to extract energy from molecules in a more efficient manner. Plastids allow plant cells to use light energy sources in order to build carbohydrates.
References
Archibald, J. M. (2015). Endosymbiosis and eukaryotic cell evolution. Current Biology, 25(19), R911-R921.
Brown, W. H., & Poon, T. (2015). Introduction to organic chemistry. Wiley.