The Bioelements Or biogenic elements (bio = life, genes = beginning) are those chemical elements that make up the matter of living beings.
There are approximately 70 of these elements, which vary in different proportions and not all are present in all living beings (Bioelements, 2009).
All matter in the universe occurs in the form of atoms of a small number of elements. There are 92 natural chemical elements in the Universe.
From our terrestrial perspective it is difficult to conceive of life forms in which the elements hydrogen, carbon, oxygen, nitrogen, sulfur and phosphorus do not play a predominant role (CHEMISTRY BIOGENIC ELEMENTS., S.F.).
The fact that they actually play this role throughout the universe seems very likely, partly because (apart from phosphorus) these are the most abundant elements throughout the cosmos in addition to occur in significant quantities between the building blocks of the terrestrial planets .
In addition, their chemistry is particularly well suited to the development of complex structures and functions that are characteristic of living systems.
Since the Sun And planets formed just 4.6 billion years ago in a universe that is perhaps 15 billion years old, it is clear that these"biogenic elements"experienced a long and complex chemical history before joining Earth's biochemistry.
At present it is not known whether this earlier history played a direct role in the origin of life on Earth.
What is clear is that astrochemistry is largely the chemistry of biogenic elements and that understanding the nature and evolution of chemical complexity across the universe is crucial to understanding both the early chemical state of our own solar system and The frequency with which related conditions exist in other parts of our galaxy and other galaxies (National Research Council (US) Committee on Planetary Biology and Chemical Evolution, 1990).
Classification of bioelements
According to their amount in the constitution of the biomolecules, the bioelements are classified as primary, secondary and trace elements (Rastogi, 2003).
1- Primary bioelements
The primary bioelements are those that are found in the greatest amount (approximately 96% of living matter) and are the ones that make up most of the organic biomolecules (carbohydrates, lipids, proteins and nucleic acids).
These elements are characterized by being light (low atomic weight) and abundant. The primary bioelements are carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur.
Carbon (C)
It is the main bioelement that constitutes the biomolecules. It has the ability to assemble to form large carbon-carbon chains through single, double or triple bonds, as well as cyclic structures.
It can incorporate a variety of functional groups like oxygen, hydroxide, phosphate, amino, nitro etc., resulting in a huge variety of different molecules.
The carbon atom is probably one of the most important bioelements since all biomolecules contain carbon. One can find, for example, lipids without phosphorus or nitrogen (for example cholesterol) but there are no carbon-free biomolecules.
Hydrogen (H)
It is one of the components of the water molecule, which is essential for life, and is part of the carbon skeletons of organic molecules.
The more hydrogen molecules a biomolecule has, the smaller it will be and the more it will oxidize, producing more energy.
For example, fatty acids have more electrons than carbohydrates, so they have the ability to produce more energy when they degrade.
Oxygen (O)
It is the other element that makes up the water molecule. It is a very electronegative element that allows a greater production of energy through aerobic respiration.
In addition, the polar bonds with hydrogen, resulting in water-soluble polar radicals.
Nitrogen (N)
Element that is present in all amino acids. Through nitrogen, amino acids have the ability to form a peptide bond to produce proteins.
This bioelement is also found in the nitrogenous bases of nucleic acids. It is eliminated by the organism in the form of urea.
One of the first biomolecules to be formed was ATP, due to the abundance of nitrogen in the Earth's atmosphere. Nitrogen is part of ATP adenosine.
Match (P)
Group is mainly found as phosphate (PO 4 3- ) That is part of the nucleotides. Form energy-rich bonds that allow for easy sharing (ATP).
It also has importance in the structure of DNA since it forms fofodiester bond with the nucleotides to form this molecule.
Sulfur (S)
A bioelement mainly found as a sulfhydryl group (-SH) that is part of amino acids such as cysteine, in which disulfide bonds are essential to create stability in the tertiary and quaternary structure of proteins.
It is also found in coenzyme A, essential for various universal metabolic pathways, such as the Krebs cycle (Llull, S.F.). It is the heaviest primary bioelement existing since its atomic weight is 36 g / mol.
2- Secondary Bioelements
These types of elements are also present in all living things but not in the same quantities as the primary elements.
They do not form biomolecules but are used in cell concentration gradients, dielectric signaling of neurons and neurotransmitters, stabilize charged biomolecules such as ATP and are part of bone tissue.
These bioelements are calcium (Ca), sodium (Na), potassium (K), magnesium (Mg) and chlorine (Cl). The most abundant are sodium, potassium, magnesium and calcium.
Calcium (Ca)
Calcium is essential for living things because plants require calcium to build cell walls.
It forms part of the vertebrate bone tissue in the form of hydroxyapatite (Ca3 (PO4) 2) 2, Ca (OH) 2 and its fixation is related to the consumption of vitamin D and sunlight. Calcium present in ionic form, serves as an important regulator of processes in the cellular cytoplasm.
Calcium affects muscle neuromuscular excitability (along with K, Na, and Mg ions and participates in muscle contraction.) Hypocalcemia leads to colic-tetany. It also participates in the regulation of glycogen synthesis in kidney, liver and skeletal muscle.
Calcium decreases the permeability of the cell membrane and the capillary wall, resulting in its anti-inflammatory, anti-exudative and anti-allergic effects. It is also necessary for blood clotting.
Calcium ions are important intracellular messengers, which influence the secretion of insulin in the circulation and the secretion of digestive enzymes in the small intestine.
Calcium reabsorption is affected by the mutual relationship of calcium to phosphates in the intestinal contents, and by the presence of cholecalciferol, which regulates the active reabsorption of calcium and phosphorus.
The exchange of calcium and phosphates is hormonally regulated with parathyroid hormone and calcitonin. The paratoid hormone releases calcium from the bones in the blood.
Calcitonin promotes calcium deposition in the bones, which lowers their blood levels.
Magnesium (Mg)
Magnesium is a secondary bioelement that is part of biomolecules since it is a cofactor of chlorophyll. Magnesium is a typical intracellular cation and is an essential part of body tissues and fluids.
It is present in the skeleton (70%) and in the muscles of animals and among its functions is to stabilize the negative charge of the phosphates of the ATP molecule.
Sodium (Na)
It is an important extracellular cation, participates in the homeostasis of the organism. It protects the body from excessive water loss through sodium channels and participates in the spread of nerve excitation.
Potassium (K)
It participates in the homeostasis of the organism and in the propagation of the nervous excitation by channels of potassium. Potassium deficiency can lead to cardiac arrest.
Chlorine (Cl)
A halogen of group VII of the periodic table. It is present in the organism of living beings mainly as chloride ion which stabilizes the positive charge of the metal ions (Biogenic elements, S.F.).
3- Trace elements
They are present in some living beings. Many of these trace elements act as cofactors in the enzymes.
The trace elements are boron (B), bromine (Br), copper (Cu), fluorine (F), manganese (Mn), silicon (Si), iron (Fe), iodine
Proportion of bioelements
There is a difference in the proportion of bioelements in organisms and in the atmosphere, hydrosphere or Earth crust , Which is indicative of a selection of elements more suitable to form structures and perform specific functions above abundance.
For example, carbon is about 20% of the weight of organisms, but its concentration in the atmosphere in the form of carbon dioxide is low. On the other hand, nitrogen makes up almost 80% of the Earth's atmosphere, however only 3.3% of nitrogen makes up the human body.
The following table shows the proportion of some bioelements in living organisms compared to the rest of the Earth (Bioelements, s.f.):
Table 1: abundance of bioelements in the universe, on earth and in the human body.
Bioelements combine together and can form thousands of different molecules. Biomolecules are involved in the constitution of cells.
These can be classified into inorganic (water and minerals) and organic (carbohydrates, lipids, amino acids and nucleic acids).
Biomolecules are known as the structural blocks of life since they are the basic bricks or molds in which more complex molecules are made up.
For example, amino acids are the structural blocks of proteins. The amino acid sequence determines the primary structure of a protein.
Molecules such as lipids form the cell membrane and simple soft carbohydrates form complex carbohydrates as is the case with the glycogen molecule.
There is also the case of the nitrogenous bases, which when attached to the ribose or deoxyribose carbohydrate, form the RNA and DNA molecules where their sequence will be read from the genetic code.
References
- Bioelements . (2009, December 14). Taken from wikiteka: wikiteka.co.uk.
- Bioelements . (S.f.). Taken from cronodon: cronodon.com.
- Biogenic elements . (S.F.). Taken from chemlaba: chemlaba.wordpress.com.
- CHEMISTRY BIOGENIC ELEMENTS. (S.F.). Taken from intranet.tdmu.edu.ua: intranet.tdmu.edu.ua.
- Llull, R. (S.F.). The living matter components . Taken from bioluliaes: bioluliaes.wordpress.com.
- National Research Council (US) Committee on Planetary Biology and Chemical Evolution. (1990). The Cosmic History of the Biogenic Elements and Compounds. In The Search for Life's Origins: Progress and Future Directions in Planetary Biology and Chemical Evolution. Washington DC: National Academies Press (US).
- Rastogi, V.B. (2003). Modern Biology. New Delhi: pitambar publishing.