Transcript MAJOR CHEMICAL COMPONENTS OF THE LIVING ORGANISMS

Medical Biochemistry
Molecular Principles of Structural Organization of Cells
MAJOR CHEMICAL
COMPONENTS
OF THE LIVING ORGANISMS
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%)
Oligobiogenic elements
(0,1-1%)
Microbiogenic elements
(<0.01%)
Ultramicrobiogenic elements (10-4-10-6%)
O, C, N, H, Ca, P.
Na, K, Cl, S, Mg, Fe.
Zn, Mn, Co, Cu, F, B, I.
Li, Al, Si, Cd, Cr, Ni.
They are constituents of organic and inorganic compounds.
Exception:
The oxygen molecular form, besides being bound to hemoglobin or myoglobin, is
dissolved in biological fluids.
There are other gases (nitrogen, inert gases) which are partly dissolved in the
biological liquids but do not take part in the biochemical processes
CHEMICAL COMPOSITION OF LIVING ORGANISMS
Organic compounds. Different cells can vary in the content of
proteins, 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 as
compared with plant cells
The water content is different
– 40% in plant cells, fat cells
– 99% in medusa
Inorganic compounds are in small number but have vital functions in
the organism
LEVELS OF MOLECULAR ORGANIZATION OF CELL
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
Monoses
Fatty acids
Alcohols
Aminoacids
Mononucleotides
(glycerol, sterols, sphingosine
Intermediary metabolites
Inorganic compounds
Components of
protein macromolecules
(heme, coenzymes)
WATER
Is indispensable for life due to its unique physical and chemical
properties 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 specified
tissue (10% in the fat tissue, 65-70% in other tissues, 80% in the blood
and kidney)
– maintained at the necessary level through intake (2 liters/day) or produced
in 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
WATER
Functions:
– Dissolution and stabilization of biological molecules and ions in the fluids of
the 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 pressure
and 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
INORGANIC IONS
Ions
Plasma (%)
Cations Na+
Total
Intracellular (%)
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
100%
100%
100%
Cl-
69.0
76.0
7.5
HCO3-
17.0
19.3
5.0
PO32-
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
100%
100%
100%
Total
Anions
Extracellular (%)
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 action
directly binding to enzymes, influencing their activity and rate of the chemical
reactions in the cell, or
Indirectly, influencing the hormonal regulation
– Transport –
electrons are transported by the cytochromes, enzymes containing Fe2+ or Fe3+ and
Cu2+;
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)