BIOCHEMISTRY

1. PHYSICAL BIOCHEMISTRY
Dr. Urender Singh
P.G -1
S.G.T Medical college Gurgaon
Haryana

2. 1. water

3. WATER
• Water is the most abundant fluid on
earth. IT is justifiably regarded as the
solvent of life.
• As much as 70% of a typical cell is
composed of water.

4. • One oxygen atom
• Two hydrogen atoms
• H2O
• Not symmetrical
• Electrons spend more time near the oxygen and less
near the hydrogen
• Water molecule is polar
Molecular Structure of Water
O
HH
++
-

5. Hydrogen Bonds Between H20
Molecules

6. Water as a Solvent
• Many important molecules in living things ,
especially sugars , have regions of partial
positive and negative charge.
• These molecules attract water molecules and
also dissolve in water . Such molecules are
called HYDROPHILIC.
• Molecules that do not have polar regions ,
such as fats , tend to be insoluble. They are
said to be HYDROPHOBIC

7. Properties of Water
• Density of water is 1g/ml.
• Boiling point --- 100 °C
• Freezing point ---0 °C
• Water is self-ionizing, that is ,there is a
tendency for a hydrogen atom to jump from
one oxygen atom to another forming OH- and
H3O+ in any volume of water there is a
constant number of molecules that are
ionized.

8. ICE
• In most liquids the density of the liquid
increases as the temperature decrees.
• However ,ice is less dense than water.
• This is because at 4 ° C the water molecules
are so close that they are all able to form
hydrogen bonds with four other molecules.
Because of the shape of the molecule, it
requires the molecules to spread out and form
an open latticework structure.

9. Resistance to Temperature Change
• The high specific heat of water is caused by
hydrogen bonding.
• Because so much energy is required to break
the hydrogen bonds , water resists
temperature change. This is important
because a number of biological processes can
occur only within a narrow temperature
change.

10. Physical States Vapor

11. BIOMEDICAL IMPORTANCE
• Water provides the aqueous medium to the
organism which is essential for the various
biochemical reactions to occur.
• Water directly participates as a reactant in
several metabolic reactions .
• It serves as a vehicle for transport of solutes.
• Water is closely associated with the regulation
of body temperature.

12. 2. Acids & Bases

13. Terms
• Acid
– Any substance that can donate a hydrogen ion
(H+) when dissolved in water
– Release of proton or H+
• Base
– Substance that can donate hydroxyl ions (OH-)
– Accept protons or H+

14. Acids & Bases
Acids:
• Arrhenius concept: Any substance that, when
dissolved in water, increases the concentration of
hydrogen ion (H+)
• Bronsted-Lowry concept: A proton (H+) donor
• Lewis concept: An electron acceptor
Bases:
• Arrhenius concept: Any substance that, when
dissolved in water, increases the concentration of
hydroxide ion (OH-)
• Bronsted-Lowery concept: A proton acceptor
• Lewis concept: An electron donor

15. Identifying Acids and Bases
Acids have a pH from 0-7 , Lower pH value indicates a
stronger acid.
Bases have a pH from 7-14 , Higher pH value indicates a
stronger base.
Ampholytes: The substances which can function both as
acids and bases are referred to as ampholytes.
Example : water
Alkalies; The metallic hydroxides such as NaOH & KOH
are commonly referred to as alkalies. These component
do not directly satisfy the criteria of bases. However,
they dissociate to from metallic ion and OH- ion. The
latter, being a base accepts H+ ions.

16. Examples of Acids & Bases
Acids
• HCL
• H2CO3
• H2PO4
• NH4+
• H2O
Bases
• H+ + CL_
• H+ +HCO3
_
• H+ +HPO4
_
• H+ +NH3
• H+ +OH_

17. Acid-Base Balance
• Function
– Maintains pH homeostasis
– Maintenance of H+ concentration
• Potential Problems of Acid-Base balance
– Increased H+ concentration yields decreased pH
– Decreased H+ concentration yields increased pH

18. 3. pH

19. pH
• pH is commonly expressed as –log[H+]
• Pure water has [H+]=10-7 and thus pH=7.
• Acids have a high [H+] and thus a low pH.
• Bases have a low [H+] and thus a high pH.

20. pH: -Acidity
• The measurement of the H+ ions found in that
particular substance
• The scale goes from 0 to 14
• 7 is neutral
• Below 7 is acidic
• Above 7 is alkaline (or basic)
• One pH unit represents a ten-fold change in
H+ concentration

21. Terms
• Acidosis
– pH less than 7.35
• Alkalosis
– pH greater than 7.45
• Note: Normal pH is 7.35-7.45

22. Ways to measure pH
pH meter
Electrode measures H+ concentration
Must standardize (calibrate) before using.
•pH paper
stripe

23. BIOMEDICAL IMPORTANCE
• pH affects solubility of many substances.
• pH affects structure and function of most proteins -
including enzymes.
• Many cells and organisms (esp. plants and aquatic
animals) can only survive in a specific pH environment.

24. 4. Buffers

25. Buffers
Definition. :
• Buffers are defined as the solutions which resist
change in pH by the addition of small amounts
of acids or bases.
• A buffer usually consists of a weak acid and its
salt (e.g. acetic acid and sodium acetate) or a
weak base and its salt (e.g. ammonium
hydroxide and ammonium chloride).

26. Buffers
• A solution that resists change in pH
• Typically a mixture of the acid and base form of a chemical
• Can be adjusted to a particular pH value
• Blood: pH = 7.35-7.45
• Too acidic? Increase respiration rate expelling CO2,
driving reaction to the left and reducing H+
concentration.
• Excretory system – excrete more or less bicarbonate

27. How buffers work
• Equilibrium between acid and base.
Example: Acetate buffer
---CH3COOH  CH3COO- + H+
• If more H+ is added to this solution, it simply
shifts the equilibrium to the left, absorbing H+,
so the [H+] remains unchanged.
• If H+ is removed (e.g. by adding OH-) then the
equilibrium shifts to the right, releasing H+ to
keep the pH constant

28. Step 1:
1)CH3COONa (aq) ————> CH3COO- (aq) + Na+ (aq)
2) CH3COOH (acetic acid)
B)After Hcl addition
CH3COO- (aq) + H+ (aq) ⇌ CH3COOH
Mechanism of buffer action

29. Step 2:
1)CH3COONa (aq) ————-> CH3COO- (aq)
+ Na+ (aq)
2) CH3COOH (acetic acid)
B)After NaOH addition
1)CH3COOH (aq) ————-> CH3COO- (aq)
+ H+ (aq)
2) H+ + OH- ---------------> H2O
Mechanism of buffer action

30. Limits to the working range of a buffer
• Consider the previous example:
– CH3COOH  CH3COO- + H+
• If too much H+ is added, the equilibrium is
shifted all the way to the left, and there is no
longer any more CH3COO- to “absorb” H+.
• At that point the solution no longer resists
change in pH; it is useless as a buffer.
• A similar argument applies to the upper end
of the working range.

31. Buffering Capacity
The efficiency of a buffer in maintaining a
constant pH on the addition of acid or base
is referred to as buffering capacity.

32. BIOMEDICAL IMPORTANCE
• pH control is important, as many enzymes have a
narrow range in which they function optimally.
• Buffering capability is essential for the well-being of
organisms, to protect them from unwelcome
changes in pH.
• For example, your stomach is about pH 1, yet the
adjacent portion of your intestine is near pH 7—
think about (or look up) how that might happen
• [Hint: what is one function of the pancreas?]
• Many compounds and macromolecules in addition
to bicarbonate can serve a buffering function—
proteins comprise one of the major classes.

33. 5. Solutions

34. Solutions
• Solutions are single phase homogeneous mixtures
of two or more pure substances.
• In a solution, the solute is dispersed uniformly
throughout the solvent.

35. Solutions
The intermolecular forces
between solute and
solvent particles must be
strong enough to compete
with those between solute
particles and those
between solvent particles.

36. How Does a Solution Form?
As a solution forms, the solvent pulls solute
particles apart and surrounds, or solvates, them.

37. Classes of Solution
 True Solution – homogeneous mixture of two or
more substances of ions or molecules. E.g. NaCl
(aq)
 Suspensions- Heterogenous mix. of two or more
then two substances ,filterable (>1000nm) E.g.
mud, freshly squeezed orange juice.
 Colloid – appears to be a homogeneous mixture,
but particles are much bigger, but not filterable.(1-
1000nm) E.g.Proteins Fog, smoke, whipped
cream, mayonnaise, etc.

38. Types of Solutions
• Saturated
Solvent holds as much
solute as is possible at
that temperature.
Dissolved solute is in
dynamic equilibrium
with solid solute
particles.

39. Types of Solutions
• Unsaturated
Less than the
maximum amount of
solute for that
temperature is
dissolved in the
solvent.

40. Types of Solutions
• Supersaturated
Solvent holds more solute than is normally possible at
that temperature.
These solutions are unstable; crystallization can usually
be stimulated by adding a “seed crystal” or scratching
the side of the flask.

41. Ways of Expressing Concentrations of
Solutions

42. Mass Percentage
mass of A solution
Mass % of A =-------------------------------X 100
Total mass of solution
A- solute
eg. 9% saline (9g/100ml solution)

43. Parts per Million
ppm =
mass of A in solution
total mass of solution
 106
Parts per Million (ppm)

44. moles of A
total moles in solution
XA =
Mole Fraction (X)
• In some applications, one needs the mole
fraction of solvent, not solute—make sure
you find the quantity you need!

45. NORMALITY (N)
•
No. of gram equivalaents of A
N= ---------------------------------------------
volume of solution in LT.
UNIT- GRAM EQ/L

46. mol of solute
Per Lt. of solution
M =
Molarity (M)

47. Molality
• No of moles of solute per 1000g of solvent.
• One molal solution can be prepared by
dissolving 1 mole of solute in 1000g of
solvent.
moll Solute
Molality(m) = ------------------------
mass of Solvent(kg)

48. Colligative Properties
• Changes in colligative properties depend
only on the number of solute particles
present, not on the identity of the solute
particles.
• Among colligative properties are
Vapor pressure lowering
Boiling point elevation
Melting point depression
Osmotic pressure

49. Energy Changes and the Solution
Process
• Intermolecular forces are also important in determining the solubility
of a substance.
– “like” intermolecular forces for solute and solvent will make the solute
soluble in the solvent.
• Hsoln is sometimes negative and sometimes positive.
– Solvent – solvent interactions: energy required to break weak bonds
between solvent molecules.
– Solute – solute interactions: energy required to break intermolecular
bonds between the solute molecules.
– Solute – solvent interactions: H is negative since bonds are formed
between them.
Solvent
Solvent – solvent
Solute
Solute – solute
+
Solution
Solute – solvent

50. 6 Colloids

51. Colloids
•Particles are too small to see but are larger
than molecules.
•Colloids are mixtures of a solvent and
suspended particles.
•Due to their small size they do not settle
out of solution.

52. Colloidal State
• Colloidal stat is the particle have size of
between true solution(less than 1nm) and
visible particle (more then 100nm)
• Example: Dispersion of starch, fine fat droplets

53. Types of colloid:
•foam (liquid + gas, e.g. whipped cream),
•emulsion (liquid + liquid, e.g. milk),
•sol (liquid + solid, e.g. paint),
•solid foam (solid + gas, e.g. marshmallow),
•solid emulsion (solid + liquid, e.g. butter),
•solid sol (solid + solid, e.g. pearl, opal).
•aerosol (gas + liquid or solid, e.g. fog
and smoke),

54. Type of colloids
• Hydrophilic colloids: colloid particales are
hydrophilic spread thoughout water (agar gel
+ proteins)
• Hydrophobic colloids: colloid system when the
colloid partical are hydrophobic polymer.
• Protective colloids: small amount of
hydrophilic colloid added to hydrophobic
colloid increse its stability.

55. Removal of Colloid Particles
Colloid particles are too small to
be separated by physical means (e.g.
filtration).
Colloid particles are coagulated
(enlarged) until they can be
removed by filtration.
Methods of coagulation:
heating (colloid particles move
and are attracted to each other
when they collide);
adding an electrolyte (neutralize
the surface charges on the colloid
particles).
Dialysis: using a semipermeable
membranes separate ions from
colloidal particles.

56. Hydrophilic and Hydrophobic Colloids
Most dirt stains on people and clothing are oil-based. Soaps are
molecules with long hydrophobic tails and hydrophilic heads that
remove dirt by stabilizing the colloid in water.
Bile excretes substances like sodium stereate that forms an emulsion
with fats in our small intestine.
Emulsifying agents help form an emulsion.

57. Hydrophilic and Hydrophobic Colloids
Sodium stearate has a long hydrophobic tail (CH3(CH2)16-) and a small
hydrophobic head (-CO2-Na+).
The hydrophobic tail can be absorbed into the oil drop, leaving the
hydrophilic head on the surface.
The hydrophilic heads then interact with the water and the oil drop
is stabilized in water.

58. Biological importance
• Biological fluids as colloids: these include blood, milk
and cerebrospinal fluid.
• Biological compounds as colloidal particles:
the complex molecules of life, the high molecular
weight proteins, complex lipids
and polysaccharides exist in colloidal state.
• Blood coagulation : when blood clotting occurs , the
sol is converted finally into the gel.
• Fat digestion and absorption : the formation of
emulsions, facilitated by the emulsifying agents bile
salts, promotes fat digestion and absorption in the
intestional tract.

59. 7. Diffusion

60. Diffusion
• Diffusion is the movement of solute
molecules from a higher concentration to a
lower concentration.
• Factors that affect the rate of diffusion: size of molecules
, size of pores in membrane, temperature, pressure, and
concentration.

61. BIOMEDICAL IMPORTANCE
• Exchange of O2 and CO2 in lungs and in tissues.
• Certain nutrients are absorbed by diffusion in the
gastrointestinal tract e.g. pentoses, minerals,
water soluble vitamins.
• Passage of the waste products namely ammonia,
in the renal tubules occurs due to diffusion.
• Increased thickness of inflamed alveolar
membrane reduces the diffusion of O2 in
pneumonia.
• Water, ion and small molecules pass largely by
diffusion through plasma membrane.

62. 8. Osmosis

63. Osmosis
• The diffusion of water across a selectively
permeable membrane.
• Osmosis is a type of Passive Transport.
• Osmosis requires NO ENERGY.

64. Osmosis – A Special kind of Diffusion
Diffusion of water across a selectively permeable membrane (a
barrier that allows some substances to pass but not others).
The cell membrane is such a barrier.
Small molecules pass through – ex: water
Large molecules can’t pass through – ex: proteins and
complex carbohydrates

65. Osmosis
• Osmosis is the movement of WATER across a
semi-permeable membrane
• At first the concentration of solute is very high on
the left.
• But over time, the water moves across the semi-
permeable membrane and dilutes the particles.

66. Similarity
Molecules move around to create
equilibrium
OSMOSIS
• Molecules go
through a
semipermeable
membrane
• Just water
DIFFUSION
• Molecules
spread out over
a large area
• Everything but
water

67. Osmosis
• Hypertonic- a solution that
causes a cell to shrink
because of Osmosis.
• Hypotonic- a solution that
causes a cell to swell because
of Osmosis.
• Isotonic- a solution that
causes no change in the size
of the cell

68. Hypotonic – The solution on one side of a membrane where the solute
concentration is less than on the other side. Hypotonic Solutions contain a low
concentration of solute relative to another solution.
Hypertonic – The solution on one side of a membrane where the solute
concentration is greater than on the other side. Hypertonic Solutions contain a
high concentration of solute relative to another solution.

69. Over time molecules will move across the
membrane until the concentration of
solutes is equal on both sides. This type of
solution is called ISOTONIC.

70. • Cytoplasm is a solution of water and solids
(solutes dissolved in the water).
• Water moves into and out of cells because of the
different concentrations of the solutes.
• Different kinds of cells react differently depending on
the solution they are in.
• Below are examples of red blood cells in different
types of solutions and shows what happened to the
red blood cells.

71. PASSIVE TRANSPORT
Passive transport occurs without expenditure of energy.
Molecules move using their own kinetic energy . Diffusion and
osmosis are examples of passive transport. Passive transport
allows cells to get water, oxygen and other small molecules that
they need. It also allows the cell to get rid of waste such as
carbon dioxide.
DIFFUSION
OSMOSIS

72. Osmotic Pressure
• Osmotic pressure: the amount of pressure necessary to stop Osmosis.
• Small molecules such as water can move through certain types of materials (membranes).
• The tendency for this to occur is related to the molarity of the solution, is also a function
of the temperature and is measured with a device called a Thistle tube.
• Osmol is the unit of osmotic pressure.
• Osmotic pressure is measured by Osmometer.

73. Reverse Osmosis
• Application of a pressure to
the solution (that is equal to
or greater than the Osmotic
pressure) and the solvent
flows from the more
concentrated side to the
other one.
• This process is used to obtain
pure water from salt water.

74. Summary
• Diffusion is the movement of molecules from an area
of higher concentration to an area of lesser
concentration.
• Osmosis is the movement of water through a semi
permeable membrane.
• Active transport requires energy. (molecules move
from an area of lesser to higher concentration)
• Passive transport needs NO ENERGY! (molecules
move from an area of higher to lesser
concentration).

75. Biological importance of osmosis
• Fluid balance - fluid balance of the different compartments of the
body is maintained due to osmosis.
• Blood volume-osmosis significantly contributes to the regulation of
blood volume and urine excretion
• Osmotic fragility test – In human blood, RBC begin to hemolyse in
0.45% NACl and the hemolysis is almost complete in 0.33% NACl. Increasd
fragility of RBC is observed in hemolytic jaundice while it is decreased in
certain anemia.
• Transfusion- isotonic solution of NACl or glucose are commonly used in
I/V transfusion in hospitals for the treatment of dehydration, burns etc.
• Action of purgatives – Epson(MgSO4 7H2O) or Glauber,s(Na2SO4
10H2O) salts withdraw water from the body ,besides preventing the
intestinal water absorption.

76. Biological importance of osmosis
• Osmotic diuresis – the high blood glucose concentration causes osmotic
diuresis resulting in the loss of water,electrolytes and glucose in urine.This is the
basis of polyuria observed in diabetes mellitus.diuresis can be produced by
administering compounds(eg.mannitol) which are filtered but not reabsorbed by
renal tubules.
•
• Edema due to hypoalbuminemia – Disorders such as kwashiorkor and
glomerulonephritis are associated with lowered plasma albumin concentration
and edema.Edema is caused by reduced oncotic presssure of plasma,leading to the
accumulation of excess fluid in tissue spaces.
• Cerebral edema – Hypertonic solutions of salts(NaCl,MgSO4) are in use to
reduce the volume of the brain or the pressure of cerebrospinal fluid
• .
• Irrigation of wounds – Isotonic solutions are used for washing wounds

77. 9 Dialysis

78. Dialysis
• The disperse phase of a colloidal system have
such large particle as cannot diffuse through
the pores of a membrane made of cellophane,
parchment, collodion, or inert cellulose ester
like cellulose nitrate or acetate. However, such
membranes are freely permeable to water
and small molecules or ion in true solution.

79. Electrodialysis
• This is the another from of dialysis. Here the
semipermeability and migration of electrolyte
ion in an electric field are utilised in separating
colloid particles from electrolyte ions.

80. BIOMEDICAL IMPORTANCE OF
DIALYSIS
• Separation of proteins from small solutes : Dialysis is used to seprate
proteins in pure form from the mixture with salts. It is used to
separate out macromolecules cell extract .Dialysis can also be used
for stopping enzymatic or metabolic reactions by removing small
cofactor molecules from the cell extract.
• Biological ultrafiltrates –Many extracellular fluids like interstitial
fluids, CSF, glomerular filtrate of kidney are formed by ultra filtration
.Proteins do not appear in ultrafiltrate.
• Dialysis by artificial kidney – In patient with acute kidney failure and
uremia ,blood is dialyzed in artificial kidneys to eliminate
nonelectrolytes waste products as well as the excess of electrolytes.

81. 10. Donnan Membrane
Equilibrium

82. DONNAN MEMBRANE EQUILIBRIUM
• When two solutions containing diffusible and non-
diffusible ions are separated by a semipermeable
membrane, the nondiffusible ions enhance the
diffusion of oppositely charged diffusible ions. The
diffusion takes place towards nondiffusible ion
containing side.
• This also reduces the diffusion of like charged ions to
that side. As a result , on the side which contains
nondiffusible ions, diffusible counterions are more
concentrated while the like charged diffusible ions
concentrate more on the opposite side. This is called as
GIBBS- DONNAN EFFECT.

83. Examples
A B
Na+[90] Na+[90] Na+[120] Na+[60]
Pr-[90] Cl-[90] Pr-[90] Cl-[60]
Cl-[30]
Sodium NaCl
Proteinate
A B

84. SUMMARY
The Donnan effect has brought the following changes in
above example
1. On the one side in which non-diffusible ion is
present,there is accumulation of oppositely charged
diffusible ions, i.e. Na+ .
2. In the other side of the membrane ,the non-diffusible
ions have made the accumulation of diffusible ions of
the same, i.e. Cl- .
3. The total concentration of all the ions will be greater
in which the non-diffusible Pr- is present leading to
osmotic imbalance between the two sides.

85. BIOLOGICAL IMPORTANCE OF
DONNAN MEMBRANE EQUILIBRIUM
• Difference in the ionic concentrations of biological fluids-The
lymph and interstitial fluids have lower concentration of inorganic cations (Na+,K+)
and higher concentration of anions(Cl-)compared to plasma. This is attributed to
the higher protein(Pr-) content in the plasma.
• Membrane hydrolysis – The relative strength of H+ and OH- ions and,
therefore, the acidic or alkaline nature on either side of a membrane, is influenced
by the presence of non-diffusible ions. This phenomenon is referred to as
membrane hydrolysis . Donnan membrane equilibrium explains the greater
concentration of H + ions in the gastric juice.
• Lower pH in RBC – The hemoglobin of RBC is negatively charged and ,
therefore causes the accumulation of positively charged ions including H+.
Therefore , the pH of RBC is slightly lower(7.25) than that of plasma(7.4)
• Osmotic imbalance – Donnan membrane equilibrium-which results in the
differential distribution of ions in different compartments of the body- partly
explains the osmotic pressure differences.

86. 11. viscosity

87. Viscosity

88. Viscosity
• Defined as the internal resistance offered by a
liquid or gas to flow .
• Viscous liquids move slower.
• The greater the intermolecular forces the
more is the viscosity.
• Poise is the unit of viscosity .

89. Viscosity of Common Liquids
Liquid Viscosity [N s/m2]
Gasoline 600
Water 1000
Milk 1200
Beer 1800
Olive Oil 40,000
#10 Motor Oil 500,000
Pancake Syrup 2,500,000
Molasses 7,300,000
Honey 10,000,000
Ketchup 50,000,000
Peanut Butter 250,000,000

90. Biological importance
• Viscosity of blood – blood is about 4 times more viscous than water . The
viscosity of blood is mainly attributed to suspended blood cells and
colloidal plasma proteins . as the blood flows through capillaries the
viscosity decreases to facilitate free flow of blood .Blood viscosity is
increased in polycythemia (elevation of RBC) , while tit reduced in anemia
and nephritis . A more viscous blood increases cardiac work load. When
dehydration occurs , the viscosity of the blood increases.
• Viscosity change in Muscle –Excitation of the muscle is associated with
increase in the viscosity of the muscle fibers . This delays the change in
the tension of the contracting muscle.
• Vitreous body – this is an amorphous viscous body located in the
posterior chamber of the eye . It is rich in albumin and hyaluronic acid.
• Synovial fluid – it contains hyaluronic acid which imparts viscosity and
helps in the lubricating function of joints.

91. 12. SURFACE TENSION

92. SURFACE TENSION

93. SURFACE TENSION

94. Surface Tension
• The surface of any liquid behaves as if it was a
stretched membrane. This phenomenon is known as
surface tension
• Surface tension is caused by intermolecular forces at
the liquid’s interface with a gas or a solid.
• Surface tension depends on the nature of the liquid,
the surrounding media and temperature.
• Liquids that have strong intermolecular forces will
have higher values of surface tension than liquids
that have weak intermolecular forces.

95. Surface tension
•Surface tension is expressed in
dynes

96. BIOLOGICAL IMPORTANCE OF
SURFACE TENSION
• Digestion and absorption of fat – bile salts reduce the surface
tension,act as detergents and cause emulsification of fat ,
thereby allowing the formation of minute particles for
effective digestion and absorption.
• Hay,s sulfur test- Hay,s test is based on the principle that bile
salt in urine lowers surface tension which is responsible for
sulfur to sink.
• Surfactant and lung function- surfactant ( dipalmitoyl lecithin)
deficiency cause respiratory distress syndrome (due to
increase in surface tension of alveoli) in the infants.
• Surface tension and adsorption-due to the coupled action of
these two process , the formation of complexes of protein and
lipid occurs in the biological system.

97. 13. Adsorption

98. Adsorption
• Adsorption is a surface phenomenon. It is the
process of accumulation of a substance
(adsorbate) on the surface of another
substance (adsorbent).
• Adsorption is differs from absorpition, as the
later involves the diffusion into the interior of
the material.

99. Adsorption
• The capacity of an adsorbent depend on the
surface area.
• Adsorption is a dynamic and reversible
process which decreases with rise in
temperature.

100. Biomedical Importance
• Formation of enzyme-substrate complex- For the
catalysis to occur in biological system, formation
of enzyme-substrate complex is a prerequisite.
This happens by adsorption of substrate on the
enzyme..
• Action of drugs and poisons-On adsorption at the
cell surface, drugs and poisons exert their action.
• Adsorption in analytical biochemistry-this
technique use for separation and purification of
compounds (enzymes , immunoglobulins)