1.3. The living matter components

Bioelement

The bioelements or biogenic elements are the chemical elements present in living things. Living matter is made up of about 70 members, almost all stable elements on Earth, except the noble gases. However, about 99% of the mass of most cells consists of four elements: carbon (C), hydrogen (H), oxygen (O) and nitrogen (N), which are much more abundant in the material living in the bark terrestre.

Types of elements

According to his speech in the constitution of biomolecules, the bioelements are classified as primary, secondary and trace elements:

Primary Bioelements

The primary bioelements are indispensable elements to form organic biomolecules (carbohydrates, lipids, proteins and nucleic acids) constitute 96% of living matter dry. Are carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur (C, H, O, N, P, S, respectively).

• Carbon. Has the ability to form long carbon-carbon chains (macromolecules) by single bonds (CH2-CH2) or double (-CH = CH-), as well as cyclic structures. May incorporate a variety of radical (= O,-OH,-NH2,-SH, PO43-), which results in a huge variety of different molecules. The links are as strong enough to form stable compounds, and also are likely to break without too much difficulty. Therefore, life is composed by carbon and silicon atom with the electronic configuration of the valence shell equals that of carbon. The fact is that the silicon-silicon chains are not stable and the chains of silicon and oxygen are virtually unchanged, and while carbon dioxide, CO2, is a water soluble gas, its equivalent in the silicon, SiO2, is a crystal solid, very hard and insoluble (silica).

• Hydrogen. Is also one of the components of the water molecule, which is essential for life and abundant in living things, is part of the carbon skeletons of organic molecules. You can link to any bioelement.

• Oxygen. Is a very electronegative element that allows the production of energy by aerobic respiration. Furthermore, polar bonds with hydrogen, resulting in water-soluble polar radicals (-OH,-CHO,-COOH).

• Nitrogen: mainly as amino group (-NH2) present in proteins as part of all amino acids. It is also found in the nitrogenous bases of nucleic acids. Virtually all the nitrogen is incorporated into the living world as nitrate ion, by plants. Nitrogen gas is only used by some soil bacteria and some cyanobacteria.

• Phosphorus. Group is found mainly as phosphate (PO43-) forming part of the nucleotides. Form energy-rich links that allow easy sharing (ATP).

• Sulfur. It is found mainly as radical sulfhydryl (-SH) forming part of many proteins where disulfide bonds essential to create stability in the tertiary and quaternary structure. It is also found in the coenzyme A, essential for various metabolic pathways universal, as the Krebs cycle.

Secondary bioelements

Essentials. They are present in all living things. Calcium (Ca), sodium (Na), potassium (K), magnesium (Mg) and chlorine (Cl). Most abundant are the sodium, potassium, magnesium and calcium. The sodium, potassium and chloride are involved in the maintenance of the salinity of the internal and load balancing in both sides of the membrane. Sodium and potassium ions are essential in the transmission of nerve impulses, calcium as carbonate results in molluscs and the skeleton of many animals. The calcium ion acts in many reactions, such as muscle contraction mechanism, the membrane permeability, etc. Magnesium is a component of many enzymes and chlorophyll. Involved in the synthesis and degradation of ATP, and DNA replication in its stabilization, etc..

Trace elements

They are present in some living things. Boron (B), bromine (Br), copper (Cu), fluorine (F), manganese (Mn), silicon (Si), , iron (Fe), iodine (I), etc..

Proportion of bioelements

The proportion of various bioelements is very different from that found in the atmosphere, hydrosphere, or the earth’s crust, they indicated that life has selected those items that are most suitable for forming structures and perform their functions. For example, carbon is about 20% of the weight of the organisms, but its concentration in the atmosphere in the form of carbon dioxide is too low, so that living concentrated extract and this element in its tissues.

The following table shows the proportion of some bioelements in human body compared with the rest of the Earth:

Biomolecules

The bioelements are combined with each other and can form thousands of different molecules. In the constitution of the cells involved biomolecules. These can be classified into inorganic (water and minerals) and organic (carbohydrates, lipids, proteins and nucleic acids)