Essential & Non-Essential Elements
Essential elements are those elements
which are required for the
maintainance of life of plants
Absence of these elements results in
death or a severe malfunction of the
Non essential elements are those
elements which don”t play any
positive role in biological systems.
Absence of these elements does not
affect the body of an organism.
Bulk elements:- They are the elements which are found in higher
Trace elements:-They are those elements which are needed in very
Essential Bulk elements
Major cation of extra cellular fluid in
Important in nerve functioning in
Major component of vertebrate
NaCl helps in osmotic regulation of
body & tissue fluids.
Na+ ions also serves as essential
activating ions for specific enzyme
Maintains the electrolyte balance in
your body's cells.
Manages your blood pressure
and keeps your heart functioning
Assists nervous system by aiding in
the correct function of tissues
needed for sending nerve impulses.
Aids in the waste removal process.
Enhances muscle control, the growth
and health of your cells.
Calcium & Magnesium
Present as carbonates &phosphates in
the skeletal structure of mammals as
about 99% of Ca2+ &70% Mg2+ .
Calcium essential for blood clotting.
Calcium stabilizes blood pressure.
Calcium contributes to normal brain
Magnesium is required for all living cells It
is catalyst for numerous biological
reaction involving the release of energy.
Mg is a constituent of bone.
Magnesium presence in extracellular
regulates the transmission of nerve
Also present in chlorophyll.
Essential Trace Elements
Iron is one of the metals found in greatest abundance in biological systems
in the form of porphyrin complexes such as haemoglobin & myoglobin.
Of total iron in the human body,70% is present in haemoglobin & about
Most of the remaining iron is stored as ferritin.
Ferritin is major iron storage protein in mammals but is also found in plant
Distributed mainly in spleen,liver &bone marrow.
Pathway of Fe2+ from food stuffs to haemoglobin and to
ferritin involves the following mechanism:-
FE3+ OF DIETERY MATERIAL IS REDUCED TO FE2+ IN THE GASTROINTESTINAL TRACT.
AFTER ABSORPTION INTO THE CELLS OF THE INTESTINAL MUCOSA,FE2+ IS INCORPORATED INTO FERRITIN AS
THE FE2+ IN MUCOSA IS ALSO CONVERTED TO FE3+ PLASMA.
PLASMA FE3+ IS IN EQUILIBRIUM WITH IRON IN THE LIVER,SPLEEN & BONE MARROW.
Cu Is a constituent of redox enzymes &hemocyanin.
The Cu in hemocyanin protein is oxygen carrier & supplies oxygen to
certain aquatic creatures &redox enzymes.
Cu containing enzymes plays an important role in the pigmentation of
skin,functioning of brain &in iron,metabolism in body in hemoglobin
Deficiency of cu in human system develops an Anemia.
Because of excess of copper,a person suffers from Wilson’s disease.
Autosomal recessive genetic disorder with onset in the 2ndor 3rd decade.
Onset in children aged 4-5yrs is also reported but rarely.
Excess Cu is deposited in excess in the liver,kidney or brain.
Cobalt-: Cobalt is also essential trace element which is essential
for many organisms including mammals.
A.)Activates number of enzymes.
B.) Highly toxic to plants.
A. Iodine is critical for formation of thyroid hormones T3, or
triiodothyronine, and T4, or thyroxine.
B. Inadequate production of thyroid hormones can cause
enlargement of the thyroid gland, also known as goiter, while its
deficiency during pregnancy can cause irreversible brain
damage in newborns.
A. Well recognized for its role in forming bones and teeth, fluoride
is present in the body as calcium fluoride.
B. Fluoride hardens tooth enamel, reduces incidence of tooth
decay and may prevent bone loss.
In addition to its role in formation of
enzymes, zinc improves immune function, helps
clot blood, maintains sense of taste and smell.
keepYou can obtain sufficient amounts of zinc
by regularly eating eggs, seafood, red
meats, fortified cereals and whole grains.
Skin healthy and enables normal growth and
Chromium and Selenium
Chromium is an important trace mineral that is
necessary for normal functioning of insulin, a
hormone that maintains blood sugar levels.
It is also essential for metabolism of
carbohydrates, proteins and fats.
Some important sources of chromium include
liver, processed meats, brewer’s yeast, whole
grains, cheese and nuts.
Selenium, along with vitamin E works as an
antioxidant that prevents damage of cells, may
prevent some cancers and is essential for the
normal functioning of the thyroid gland.
Meat, seafood, nuts and cereals are good
sources of selenium.
ESSENTIAL TRACE ELEMENT FOR PLANT UREASES.
DEFICIENCY IN FOOD SLOWS DOWN THE FUNCTIONING OF LIVER IN CHICKS &RATS RAISED ON DEFICIENT
HIGHLY TOXIC TO MOST PLANTS & MODERATELY TOXIC TO MAMMALS.
CARCINOGENIC IF PRESENT IN LARGE CONC. IN BIOLOGICAL SYSTEMS.
ULTRATRACE ELEMENT IN RED ALGAE,CHICK,RAT,PIG,GOAT &SOME MAMMALS INCLUDING HUMANS.
DEFICIENCY IN CHICKS RESULTS IN DEPRESSED GROWTH.
MODERATELY TOXIC TO PLANTS &HIGHLY TOXIC TO MAMMALS WHEN PRESENT IN MORE THAN ULTRA
Porphines are macrocyclic rings made of four pyrolle rings linked
together through methane bridges.these porphines have pyrolle
system with double bonds.therefore act as tetradentate ligands with
nitrogen donor sites.
Two of these are tertiary nitrogen donor positions which can form
coordinating bonds by donating a pair of electrons each to the metal
The other two are secondary nitrogen donor positions,each of which
can lose a proton in forming a coordinate bond with a metal ion.
Thus,a porphin ring can act a a tetradentate dinegative ligand.
When the four pyrolle rings of porphin carry substituents other than
hydrogens,these are called porphyrins.
These substituents are usually organic groups with electron
withdrawing or electron donating characteristics.
The complexes in which a metal ion is held in the porphyrin ring
system are called Metalloporphyrins.
The porphyrin ring system is rigid because of the delocalization of
electrons in the pyrolle rings.
Metal complex with
The nature of metalloporphyrins vary with the nature of the metal ion porphin ligand
&the type of organic substituents on the porphyrin structure.
Heme is an iron porphyrin which is present in hemoglobin and myoglobin.
Chlorophyll is magnesium complex of porphyrin which plays important role in
the process of photosynthesis.
Photosynthesis is an important redox reaction occurring in nature to convert
water & Carbon dioxide into carbohydrates &oxygen in the presence of solar
In this metalloporphyrin,in addition to substituents,a double bond in one of the
pyrolle rings is reduced to form magnesium dyhydrido porphyrin complex as
Structures of heme &chlorophyll
Hemoglobin is a large protein with a
molecular weight of about 64500.
Consists of four subunits each of
which contains one heme group
associated with protein globin.
Therefore,there are 4 heme groups
bonded to four protein chains.one
heme group with its protein is called
Froms alpha chains of 141 amino
acids&two forms beta chains of 146
An outline structure of
Myoglobin is relatively a small protein of
molecular weight of about 17000.
Consists of one polypeptide chain (globin)
with one heme group (iron porphyrin
complex) embedded their in.
The peptide chain consists of 150-160 amino
acid residues folded about the single heme
group as shown in figure.
Heterocyclic ring system of heme is porphyrin
derivative containing 4 pyrolle rings labelled
as A,B,C,D joined by methane bridges.
The Fe atom present at the centre of the heme
is bonded by four porphyrin nitrogen atoms
&one nitrogen atom from imidazole side chain
of histidine residue.
Polypeptide chain plays an important role in
biological fixation of Oxygen.
ROLE OF HEMOGLOBIN & MYOGLOBIN
Hemoglobin &myoglobin plays very important role in transporting oxygen from lungs to
tissues & Carbon dioxide.
Oxygen is inhaled into the lungs at very high pressure where
it binds Hb in the blood forming HbO2.
The oxygen is then transported to respiring tissues whre the
partial pressure of O2 is low.
The O2 then dissociates from Hb & diffuses to the tissues
where myoglobin picks it up &stores until it is needed.
Myoglobin has a great affinity for O2 then Hb.
This increases the rate od diffusion of O2 from the capillaries
to the tissues by increasing its solubility.
The Hb & CO2 (as HCO3- ) are then returned to the lungs
where CO2 is exhaled.
• The main function of hemoglobin is to bind O2 at high partial
O2 at high partial
pressure of O2 found in the lungs &then carry it without any loss
O2 found in the lungs &then carry it without any loss
through the blood to the tissues where myoglobin picks up O2
• In the lungs,where the pressure of O2 is high &much O2 isis
O2 is high &much O2
bound,the affinity of heme fro O2becomes very high . .
O2 becomes very high
• But when Hb reaches the cells where the pressure of O2 is low &
O2 is low &
O2begins to dissociate from the complex.
O2 begins to dissociate from the complex.
• This information is passed on so that the remaining heme groups
also unload their O2 groups.
• The myoglobin picks up all the O2.
• Since myoglobin has only one heme group .it does not have any
cooperative binding so it does not lose its affinity fro O2.this shows
shows that myoglobin has higher affinity then Hb at low partial
that myoglobin has higher affinity for O2 for O2 then Hb at low
partial pressure of O2 in the muscle.
pressure of O2 in the muscle.
• Myoglobin has only one heme group per molecule &the binding
between the iron &the oxygen molecule is similar to that in Hb but
the equilibrium is simpler because only one oxygen molecule is
Its very interesting to study the oxygenation behavior vs oxygen
pressure Po under physiological conditions for myoglobin & Hb.
The reversible binding of O2 to Mb may be represented by the simple equilibrium
Mb + O
The equilibrium constant K may be expressed as:-
K = [MbO ]
[Mb] [O ]
K= [MbO ] ……………………(2)
(P = Equilibrium partial pressure of oxygen)
Let us define a term fractional oxygen saturation ,θ which represents the Ratio of the
concentration of the Mb present as MbO2 to the total concentration of Mb. i.e.
θ = [MbO ]
From eq. (2) & (3),we get,
This is the equation for the hyperbolic curve .This curve shows that as partial pressure of O
increases,more of O2 binds to Mb.At very high partial pressure of O2,almost all the O2
binding sites are occupied &Mb is said to be saturated with O2.At a partial pressure of
2.88 torr,Mb is half saturated with O2. When Mb is half saturated θ is 0.5 so that partial
pressure of oxygen, P1/2 is
K = θ
K = 0
P1/2 (O ) = 1
Thus,at 0.5 or 50% saturation ,K is defined as inverse of partial
pressure of O2 at 50% saturation (θ =0.5)
Hb having four subunits has more complex behavior.Fractional
oxygen saturation in case of Hb is given by the expression :
The exact value of n depends upon the pH.The
shape of the Hb binding curve is not like the hyperbolic
curve of Mb.The HbO2 binding curve is described by
The variation of oxygen affinity with the pH of
the medium is called Bohr”s effect.
It is also called pH sensitivity effect.
According to this effect,the affinity of Hb for
O2 decreases with decreasing pH.
However,blood is buffer so that the decrease
in pH is very small with accumulation of CO2
The decreasing affinity of Hb for O2 with
decreaing pH is shown in graph.
Bohr “s effect has important physiological
effect in transporting O2 from the lungs to the
respiring tissues &in transporting CO2
produced there back to lungs.
The CO2 produced diffuses from the muscles
tissues to the capillaries & dissolved CO2 forms
bicarbonate only very slowly.