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MAJOR CHEMICAL

COMPONENTS

OF THE LIVING ORGANISMS

Medical Biochemistry

Molecular Principles of Structural Organization of Cells

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CHEMICAL COMPOSITION OF LIVING ORGANISMS

In the human organism there are 70 elements of the Periodic Table,

which may be divided in four groups:

Macrobiogenic elements (>1%) O, C, N, H, Ca, P.

Oligobiogenic elements (0,1-1%) Na, K, Cl, S, Mg, Fe.

Microbiogenic elements (

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CHEMICAL COMPOSITION OF LIVING ORGANISMS

Organic compounds. Different cells can vary in the content ofproteins, nucleic acids, lipids, polysaccharides, for example: Liver and muscle cells are rich in polysaccharides

Fat tissue cells are rich in lipids

Animal cells are rich in proteins and rather depleted in nucleic acids ascompared with plant cells

The watercontent is different 40% in plant cells, fat cells

99% in medusa

Inorganic compounds are in small number but have vital functions inthe organism

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Cell

Cellular organelles

(nuclei, mitochondria,etc)

Enzymes complexes, ribosomes, nucleoli, contractile system

Conjugated proteins:

Glycoproteins, Lipoproteins, Phosphoproteins, Nucleoproteins, Metalproteins, Chromoproteins

Polyglucides Lipids

Proteins

(apoenzymes) Nucleic acids Components ofprotein macromolecules

(heme, coenzymes)

MonosesFatty acids

Alcohols(glycerol, sterols, sphingosine

Aminoacids Mononucleotides

Intermediary metabolites

Inorganic compounds

LEVELS OF MOLECULAR ORGANIZATION OF CELL

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WATER

Is indispensable for life due to its unique physical and chemicalproperties and importance for biological activity of living organisms

Content 45-75% of the total body mass depends on age (new born 75%, >50years 45-50%)

the content varies depending on the metabolic processes in the specifiedtissue (10% in the fat tissue, 65-70% in other tissues, 80% in the bloodand kidney)

maintained at the necessary level through intake (2 liters/day) or producedin the metabolic processes (0.3 liters/day)

Distribution: In the cells (intracellular)

Outside the cells

extracellular fluids (12-16%),

blood plasma (5%),

lymph (2%)

Within closed cavities (intra-cavity water)(1-3%): cerebrospinal fluid,intraocular, pericardial, synovial fluid etc

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WATER

Functions:

Dissolution and stabilization of biological molecules and ions in the fluids ofthe organisms

Heat balance control - uptake, conservation, distribution and release of heat

Transport supply of nutrients and excretion of waste products

Mechanical (by hydration) assistance in maintaining intracellular pressureand shape of cells

Structural

forming an interlayer between the polar ends of protein and lipids

in biological membranes

Synthetic (anabolic) substrate in the synthesis of biological compounds

Hydrolytic (catabolic) substrate in the bond-breaking processes

Energetic (electron donating)

The cell functions are dependent on: The total amount of intra and extracellular water

Hydration of sub-cellular structures

Aqueous microenvironment of macromolecules

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INORGANIC IONS

Ions Plasma (%) Extracellular (%) Intracellular (%)

Cations Na+ 92.2 94.0 7.5

K+ 3.0 2.7 75.0

Ca2+ 3.0 2.0 2.5

Mg2+ 1.3 1.3 15.0

Total 100% 100% 100%

Anions Cl- 69.0 76.0 7.5

HCO3- 17.0 19.3 5.0

PO3

2- 1.4 1.4 50.0

SO42- 0.6 0.7 10.0

organic 2.0 2.0 2.5

protein 10.0 0.6 25.0

Total 100% 100% 100%

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INORGANIC IONS

Functions Bioelectric functions development of potential difference across the cell

membrane (neurons, muscle cells)

Osmotic functions control of osmotic and hydro-osmotic pressure

Structural metal ions constituents of macromolecules (proteins, heme)

Regulatory cations exert regulatory actiondirectly binding to enzymes, influencing their activity and rate of the chemicalreactions in the cell, or

Indirectly, influencing the hormonal regulation

Transportelectrons are transported by the cytochromes, enzymes containing Fe2+ or Fe3+ andCu2+;

oxygen is bound to Fe2+

in the structure of hemoglobin Energetic inorganic phosphate in ATP

Mechanical (support) Ca and P ions are constituents of bones (strength)

Synthetic complex molecules contain I- (hormones), SO42- (ester sulfuric

compounds)