This document provides information on biological molecules. It begins by defining biomolecules as molecules involved in living organisms that are typically made up of carbon, hydrogen, oxygen, nitrogen and other elements. The main types of biomolecules discussed are carbohydrates, lipids, proteins, nucleic acids and water. Carbohydrates include monosaccharides like glucose and fructose, disaccharides like sucrose, and polysaccharides like starch, cellulose and glycogen. Lipids include fats, waxes, phospholipids, glycolipids and sterols. The properties of water that allow it to act as the universal solvent in living systems are also summarized.

1. Unit-2
Biological molecules
By – Suman Tiwari (M.Sc.,M.Ed.)

2. Biological molecules
•A biomolecule or biological molecule
•It is a loosely used term for molecules and ions present
in organisms that are essential to one or more
typically biological processes, such as cell
division, morphogenesis, or development .
•Biomolecules are usuallyendogenous, produced within the
organism but organisms usually
need exogenous biomolecules, for example certain nutrients,
to survive.

3. •Biomolecule: any molecule that is involved in the
maintenance and metabolic processes of living
organisms. Biomolecules include carbohydrate,
lipid, protein, nucleic acid, and water molecules.
Biomolecules consists mainly of carbon and hydrogen
with nitrogen, oxygen, sulphur, and phosphorus.
Biomolecules are very large molecules of many atoms
that are covalently bound together. Biomolecules are
usually endogenous but may also be exogenous.
•All the carbon compounds we get from living tissues can
be called biomolecules.
Biological molecules

4. •Biology and its subfields of biochemistry and molecular
biology study biomolecules and their reactions. Most
biomolecules are organic compounds, and just
four elements—oxygen, carbon, hydrogen,
and nitrogen—make up 96% of the human body's mass.
But many other elements, such as the various biometals,
are present in small amounts.
Evolution of life – Electric discharge Experiment
https://safeYouTube.net/w/HDBA
Biological molecules

5. Biological molecules

6. Cells Molecules
Organic Inorganic
-Proteins
-Carbohydrates
-Fats
-Nucleic acid
-Amino acid
-Polysaccharides
-Minerals
( 17 essential in plants
24 essential in animals )
-Ions
-Water
Biological molecules

7. Biological molecules
Living
Cells
Trichloroacetic
acid
Acid insoluble pool
(Molecule have molecular
wt. more than 10000
Daltons)
Acid soluble pool
(Molecule have molecular
wt. 18 to 1000 Daltons)

8. Biological molecules
Molecular
Weight
Macromolecules
(Above 10000)
Micromolecules
(Between 18 to 1000)
-Monosaccharide
-Disaccharide
-Oligosaccharide
-Amino acids
-Lipids
-Nucleotides
-Polysaccharide
-Proteins
-Nucleic acids
(DNA , RNA )

9. •Monomer: simple molecule which is used as a basic
building block for the synthesis of a polymer; many
monomers are joined together to make the polymer,
usually by condensation reactions e.g. monosaccharides,
amino acids, nucleic acids.
• Polymer: is a giant molecule made from monomers e.g.
polysaccharides, proteins, nucleic acids.
Types
Natural polymers : Cellulose , Rubber.
Synthetic / Artificial polymer: Polyester, Polythene, PVC
(Polyvinyl chloride and Nylon)
•

10. Macromolecule: These are large and complex molecules
that are formed due to polymerisation of smaller
monomers e.g. polysaccharides, nucleic acids.

11. •Carbohydrates (Saccharides)
•Made up of C, H, O in the ratio of 1:2:1
•As they contain: C H2O (Hydrates of C)
•General Formula : Cn H2n O n
•They are of different types based on number of carbon
atoms:
•1. Monosaccharides (1 Carbon)
•2. Disaccharides (2 Carbon)
•3. Oligosaccharides (3-7 Carbon)
•4. Polysaccharides (1000 Carbon monounits)
Carbohydrates

12. •Number of Carbon : 3-7
3- Carbon: Triose sugar. E.g. -glyceraldehyde
4- Carbon: Tetrose sugar. E.g.- Erythrose
5- Carbon: Pentose sugar. E.g.- Ribose, Arabinose
6- Carbon: Hexose sugar. E.g.- Glucose, Fructose, Galactose.
7- Carbon: Heptose sugar. E.g.-Sedoheptulose.
Monosaccharides

13. •Two common example : Glucose and Fructose
•Hexose sugar has two categories:
•Aldehyde group and keto group and are named aldose
and ketose respectively.
•They are polyhydroxy compounds.( many –OH group)
•Structure of Glucose: An aldose sugar having an
aldehyde group at terminal carbon.
•Glucose exist in two forms :
Open chain
Ring form
These two forms are interconvertible.
Hexose sugar

14. Pyranose ring:
5Carbon &
1 Oxygen.
Hexagonal
structure
Structure of Glucose
(Aldose Sugar )
Open chain
Close chain
The bond formed between an aldehyde and hydroxyl group is
called glycosidic bond. This bond is always formed by the
elimination of a water molecule. If this bond is formed
between the same molecule, its called as hemiacetal bond.

15. Structure of Glucose

16. Structure of Fructose
(Ketose Sugar )
Pentagonal -
4Carbon &
1 Oxygen
Such ring is
called Furanose
ring
Both Glucose and Fructose are reducing sugars as they convert
cuprus to cupric as they have aldehyde or keto group
Fructose is commonly known as fruit sugar.
Glucose and Fructose are isomers of each other
Open chain Close chain

17. Structure of Fructose

18. •C-5 -E.g. Ribose, deoxyribose, Arabinose
Pentose sugar
Ribose sugar has two functional group so it is more
reactive than deoxyribose.

19. •Disaccharides are formed by joining two monosaccharides
units by a glycosidic bond.
•1. Maltose ,common Malt sugar( Glucose + Glucose)-
Reducing sugar as one aldehyde group is present.
Disaccharides
1-4, glycosidic bond

20. •2. Sucrose, common cane sugar (Glucose + Fructose). It
is a non-reducing sugar as no functional group.
Disaccharides

21. •3. Lactose, common milk sugar(Glucose + Galactose). It is
a reducing sugar.
Disaccharides
1-4, Glycosidic bond

22. The principal reagent in Benedict's Test for Reducing Sugars
is Benedict's Solution which contains:
•copper(II) sulphate
•sodium carbonate
•sodium citrate
•Reducing sugars are simple sugars and include all
monosaccharides and most disaccarides. Some examples of
monosaccharides are glucose, fructose and
galactose.Examples of reducing disaccharides are lactose
and maltose.
Note that the disaccharide sucrose is not a reducing sugar.
In fact, sucrose is the most common non-reducing sugar.
Video Link :https://safeYouTube.net/w/OCmC
Benedict’s Test

23. Sugars are classified as reducing or non-reducing based
on their ability to act as a reducing agent during the
Benedict's Test. A reducing agent donates electrons
during a redox reaction and is itself oxidized.
The aldehyde functional group is the reducing agent in
reducing sugars. Reducing sugars have either an
aldehyde functional group or have a ketone group - in an
open chain form - which can be converted into an
aldehyde.
• http://brilliantbiologystudent.weebly.com/benedicts-test-for-
reducing-sugars.html
Video for Non-reducing sugar :
https://safeYouTube.net/w/sFmC
http://brilliantbiologystudent.weebly.com/benedicts-test-for-
non-reducing-sugars.html

24. Polysaccharides
Polysaccharides
( on the basis of
monounits)
Homosaccharides
(Same units)
Heterosaccharides
(Different units)
Cellulose Hemicellulose

25. Polysaccharides
Polysaccharides
( on the basis of
function)
Storage
polysaccharide
Structural
polysaccharides
Starch Cellulose

26. •Its a storage polysaccharide.
•Its a homopolysaccharide(monounit-Glucose).
•It is made up of two components – Amylose and
Amylopectin.
•Amylose contains 200-2000 glucose chain. It has 1,4-
Glycosidic bond. It has a linear but highly coiled structure
•Amylopectin contains 2000- 20,000 glucose units.It has
1,4- Glycosidic bond as well as 1,6- Glycosidic bond as a
result they have a branched structure.
•Ratio of amylose to amylopectin in a starch molecule is
1:3.
•The blue-black colour of starch with iodine is due to
amylose.
Starch

27. Starch

28. •Storage of starch is usually done in grain forms in a cell.
•These grains are classified as simple starch grain and
compound starch grain.
•Simple grain has one point around which the starch
layers deposit.
•Point is made of Hilum.
•If one hilum present then simple starch grain if more
than two compound starch grain.
Starch

29. • It is a storage polysaccharide. As it found in animals only so also
known as animal starch.
• It is a homopolysaccharide. (Monounit –Glucose)
• It is stored in liver and muscle cells.
• It has 1,4- alpha glycosidic bond( gives linear structure) and many
1,6-glycosidic.
• It produces red colour with Iodine solution.
Glycogen

30. •It is a structural polysaccharide.(makes cell wall)
•It is a homoplysaccharide. (Monounit –Glucose)
•Bond in case of cellulose is Beta 1,4- Glycosidic bond.
•It has a linear structure.
Uses
•Cotton fibres are 90% cellulose
•Jute, hemp have 40% of cellulose
•Cellulose+ Base= Rayon ( A synthetic fibre)
•Cellulose acetate is used for making shatterproof glass
•Cellulose nitrate is used to make explosives
•Carboxy methyl cellulose is used for making ice-creams.
Cellulose

31. Cellulose

32. •It is a homopolysaccharide.
•It is a structural polysaccharide.
•Monounit is N-Acetylglucoseamine.
•It is found in the cell walls of Fungi and exoskeleton of
Arthropods.
Chitin

33. Inulin
It is a homopolysaccharide.
• Monounit is Fructose.
• It is found in the roots of Dahlia plant
Agar
It is a homopolysaccharide.
• It is a structural polysaccharide.
• Monounit is Galactose.
• It is extracted from red algae.
• It is used to make nutritive medium.
Hemicellulose
It is a heteropolysaccharide.
• Monounit is galactose,Mannose, Xylose and Arabinose.
Some other
polysaccharides

34. •The polar nature of water molecules
•An important feature of the water molecule is its polar
nature. Polar molecules once placed into water dissolve
and dissociate into water ions. Ionic molecules when
they are placed into water dissociate into ions. Since
oxygen has a higher electronegativity than hydrogen, the
side of the molecule with the oxygen atom has a partial
negative charge. A molecule with such a charge
difference is called a dipole.
Water

35. Hydrogen bond

36. •Hydrogen bonding in water
•A bond between molecules where the slightly positive
hydrogen atoms in one water molecule are attracted to
the slightly negative oxygen atom in another water
molecule. The type of attraction is a weak interaction
that occurs between a slightly negatively charged atoms
and a slightly positively charged atom. It is weaker than a
covalent bond but is the strongest intermolecular forces.
Each of the individual hydrogen bonds is weak, where
water forms many of these hydrogen bonds.
•A hydrogen bond is a weak interaction that occurs
between slightly negatively charged atoms and a
slightly positively charged atom.
Water

37. Many of the properties stated below are due to its dipolar
nature and subsequent hydrogen bonds it forms and
allows.
•1. Solvent
•Water is a good solvent since it is a charged molecule
allowing them to easily be transported alongside this its
water molecule’s dipole nature allows other polar
molecules to be readily dissolved into water. Such
examples of charged polar molecules such as salts,
amino acids and sugars are able to readily dissolved in
water. They are termed as hydrophilic; “water-loving”
molecules. Non-polar molecules such as lipids are
termed as hydrophobic, “water-hating”.
Physical Properties of
water

38. •2. High heat capacity
•The tendency of water molecules to stick together is
known as cohesion. Hence it would take a lot of heat
energy to separate molecules that are stuck together
rather than if they were not bonded together. Relating
this to water, water does not change temperature very
easily as it has a specific heat capacity of 4.2 J g-1 °C-1
which in simple terms means it takes 4.2 joules of energy
to heat 1 g of water by 1 °C. This is remarkably high and
is what keeps aquatic and cellular environments stable.
Water

39. •3. High Latent heat of Vaporisation
•Hydrogen bonding between the water molecules allows
it to have a high latent heat of vaporisation. Therefore, a
large amount of energy is needed to change water from
a liquid state into a gaseous state, where evaporation
has a cooling effect on organisms such as sweating in
animals and transpiration in plants.
Water

40. •3.Density
•Water has a unique property that in a solid state (ice) it
is less dense that the liquid state and is able to float on
water. This property is different for the normal situation
as most substances are in a gas form when they are less
dense and more dense are in a solid state. This shows
how water is different. The property of water makes it
crucial for aquatic organisms to be able to survive in
freezing sub-zero temperatures such as in ponds, lakes
etc.
Water

41. •4.Cohesion and surface tension in water
• Water has properties of being cohesive, where they have a
tendency to stick to other molecules together. This is due to the
hydrogen bonding within water molecules that causes it to have a
large cohesive forces which allows for the water to be pulled
through a tube for example in plants; xylem vessels which are long
tubes that help in the transportation of water to provide the plan
with mechanical support. Another force called surface tension is
also an unique property of water. Surface tension is the attractive
force that can be exerted upon the surface of other molecules of a
liquid which gives the tendency of the fluid surface to shrink into
minimum surface area rather than the body of water escaping.
Surface tenion of water allows for skaters to walk on water or allow
insects that are usually denser than water, float on a water surface.
Water

42. • 5. pH
• Water itself is partially ionized and has a source of H+ ions that
cause for several biochemical reactions to be sensitive to pH
changes. Pure water is not buffered at a neutral pH unlike the
cytoplasm and tissue fluids within living organisms that are buffered
at neutral pH 7.5.
• 6. Ionization
• Ionization is the process for forming or splitting of molecules to
their cations and anions. An example is when sodium chloride
(NaCl) dissolve into water they ionize and separate into positive and
negative ions (Na+, Cl–).
Water

43. Lipids
Lipids
Simple Conjugated
Lipid
derivatives
Esters of fatty
acids and
alcohol
True fats or
Neutral Lipids
Waxes
Esters of fatty acid
and glycerol
Esters of fatty acid
and alcohol other
than glycerol.

44. Conjugated
Lipid
derivatives
Simple lipid+
Non lipid part
-Phospholipid
-Glycolipid
- Lipoprotein
Sterols Terpenes

45. •Esters of Fatty acid and Glycerol.
•Fatty acids are classified into two types( -R-COOH )
1. Essential fatty acids
2. Non-essential fatty acids
Essential Fatty acid :
1. Linolic Acid (gives Omega 6)
2. Alpha Linolenic Acid (gives Omega 3)
3. Archedonic Acid (it is synthesised from Linolic acid)
Other then these 3 all other Fatty acids are non-essential
fatty acids.
Simple Lipid: True or
Neutral Fats

46. • Saturated FA- Hydrocarbon chains have single bonds
• Unsaturated FA- Hydrocarbon chains have double and triple bonds
Types of Fatty Acids
Glycerol head
(Hydrophilic)
Fatty Acid Tail
(Hydrophobic) Amphipathic
Molecules

47. Based on number of fatty acids chain attached to a
Glycerol head they are of three types:
•Monoglycerides- One tail.
•Diglycerides- Two tails.
•Triglycerides- Three tails.
Hence True fats are of two types:
1. Saturated Fats- Glycerol + saturated fatty acid
(They are solid at room temperature)ex. All animal fats
2. Unsaturated Fats- Glycerol + unsaturated fatty acid
(They are liquid at room temperature)ex. All plant fats
Neutral/True Fats

48. •Functions of Neutral Fats:
1. Subcutaneous fats are deposited under the skin layer
and act as insulators.
2. Deposited around the organs- to protect it from
mechanical shock
3. Reserve form of energy- stored in body as a reserve
form of energy.
Neutral Fats

49. Esters of fatty acids and alcohol other than glycerol.
1. Plant waxes- with substance cutin it forms the cuticle
layer in plants. Mostly found in Hydrophytes.
2. Bee wax- Wax produced by honey bees to make their
hives, these are secreted by the wax glands in the last
abdominal segment of worker bees. It is soft and
yellow in colour.
3. Ear wax(Cerumen)- Secreted by cerumen part of
internal ear. It helps to protect our ear drum.
4. Sebum (oil)- Secreted by sebaceous gland .
5. Lanolin-Wool wax
Waxes

50. • 1. Phospholipid- ex. lecithine . Phospholipid are found in
plasma membrane. They have a phosphate group
attached to the head of a simple lipid.
•2. Glycolipid- It has a carbohydrate group attached to a
simple lipid. It is found on plasma membrane. It a
protective protein.
• 3. Sphinglipids- Lipid + Nitrogen base. It is found in
plasma membrane and nervous tissues.
•4.Lipoprotein- simple lipids + protein. The role
of lipoprotein particles is to transport fat molecules,
such as triacylglycerols (also known as triglycerides),
phospholipids, and cholesterol within the extracellular
water of the body to all the cells and tissues of the body.
Conjugated Lipids

51. Sterols( steroid alcohol)
1.Phytosterol-If found in plants they are called
phytosterols. Ex. (i)Stigmasterol- obtained from
soyabean, also used to obtain progesterol.
(ii) Sitosterol-obtained from wheat.
2. Engosterol- Obtained from Fungi. Found in plasma
membrane.
3. Zoosterol- Obtained from animals. Ex. Cholesterol. It
acts as an insulators. In plasma membrane it provides
strength to it.
4. Steroid hormones- Progesterone, Testosterone,
oestrogen.
5. Vitamin D.
Derived Lipids

52. •Terpene- Derivatives of a 5 carbon compound called
Isoprene
•1. Natural rubber- It is a polyterpene
•2. Vitamin A
•3. Carotenoids
They impart specific odour to like Camphor, Eucalyptus
oil, menthol
Derived Lipids

53. •The Ethanol Emulsion Test is a food test which
determines the presence of a broad group of naturally
occurring compounds known as lipids. Lipids consist
of fats and oils.
Video Link : https://safeYouTube.net/w/eIsD
Sudan III Test
Sudan III is a red fat-soluble dye that is utilized in the
identification of the presence of lipids, triglycerides and
lipoproteins. The Reaction: Sudan III reacts with
the lipids or triglycerides to stain red in colour.
Video Link: https://safeYouTube.net/w/SOsD
Test for the presence of
Lipids

54. •Proteins are an extremely important class of
macromolecules in living organisms. More than 50% of
the dry mass of most cells is protein.
•All proteins are made from the same basic monomers.
These are amino acids.
Proteins

55. •There are 20 AA required for protein synthesis.
•There are 100 AA required for other functions of life.
•They are also known as methane derivatives.
•It has an amino group (basic nature) and a carboxyl
group( acidic nature)
Amino acids

56. •If A = C : Neutral AA. Ex- Glycine, Serine
•If A > C: Basic. Ex- Lysine, Arginine
•If A < C: Acidic. Ex- Glutamic acid, Aspartic acid
Classification of AA
1. Essential AA- Tryptophan, Methionine, Phenylalanine
2. Non- essential AA- Glutamic acid, Aspartic acid, Alanine
3. Semi-essential AA( growth and lactation period)-Histidine,
Arginine
•Video link : https://safeYouTube.net/w/XqFD
Amino acids

57. • The amino acids of a polypeptide are attached to their neighbours
by covalent bonds known as a peptide bonds. Each bond forms in a
dehydration synthesis (condensation) reaction. During protein
synthesis, the carboxyl group of the amino acid at the end of the
growing polypeptide chain chain reacts with the amino group of an
incoming amino acid, releasing a molecule of water. The resulting
bond between amino acids is a peptide bond.
Peptide bond

58. •Berzelius suggested the name for molecules studied by Mulder.
•They are also Known as polypeptides.
•On the basis of number of chains it had been divided into :
1. Monomeric protein- made up of only one polypeptide chain .
Ex.: Lysozyme (found in saliva, tears), Myoglobin.
2. Multimeric protein- made up of many polypeptide chains.
Ex.: Haemoglobin( It has two alpha chain and two beta chains ,
hence four polypeptide chains).
Insulin(one alpha and one beta chain).
Protein
(Macromolecule)

59. Classification on the basis of AA types present:
1. First class/Complete protein- It has all essential and non
essential AA.
Ex. Animal Proteins
2. Second class/ Incomplete protein- It lack some AA.
Ex. Plant Proteins
Proteins

60. • Classification on the basis of structure:
1. Primary structure:
• Only have peptide bonds.
• Normally they are non functional, except Insulin .
• Even a change in one amino acid in a chain made up of thousands
may completely change the properties of the polypeptide or protein.
• The free α-amino group, written to the left, is called the amino-
terminal or N-terminal end. The free α-carboxyl group, written to the
right, is called the carboxyl-terminal or C-terminal end.
Primary Structure
Proteins

61. Proteins

62. 2. Secondary structure:
• They are structural proteins.
• Along with peptide bonds they also have hydrogen
bonds.
• They make an alpha helix( If hydrogen bond within the
same chain AA) and beta pleated( If hydrogen bond is
between two different polypeptide chain)structure.
• Ex.: Alpha- Keratin, Beta- Silk fibre.
Proteins

63. The most common helical coil is a right-handed α-helix.
• α-keratin from hair and nails is an α-helical protein.
Myoglobin has several α-helical regions.
• Proline, glycine, and asparagine are seldom found in
α-helices; they are “helix breakers.”
In β-sheets (pleated sheets), the hydrogen bonds occur
between residues on neighbouring peptide chains.
• The hydrogen bonds may be on different chains or
distant regions of the same chain.
The strands may run parallel or antiparallel.
Fibroin in silk is a β-sheet protein.
Proteins

64. 3. Tertiary Structure:
• It has three polypeptide chains.
• They are specifically functional proteins as they have
active sites.
• Peptide bond, hydrogen bond, ionic bond, disulphide
bond.
• Ex.: Enzymes
Proteins

65. 4. Quaternary structure:
• It has four polypeptide chains.(2 alpha 2 beta chains)
• They are also specifically functional.
• Chains are held together by electrostatic bonds.
• Peptide bond, hydrogen bond, ionic bond, disulphide
bond.
• Ex.: Globin of haemoglobin
Proteins

66. Globular and fibrous
Proteins

67. •There are two main classes of protein tertiary structure:
•Fibrous proteins are generally composed of long and
narrow strands and have a structural role
(they are something)
•Globular proteins generally have a more compact and
rounded shape and have functional roles
(they do something)
Globular and fibrous
Proteins

68. Comparision

69. • Haemoglobin, is a globular protein.
•It is composed of 2 α +2β Polypeptide chains + 1
inorganic prosthetic haem group
Haemoglobin(Hemoglobin)

70. Haemoglobin

71. Collagen

72. Collagen

73. • Denaturation is a structural change in a protein that results in the
loss (usually permanent) of its biological properties
• Because the way a protein folds determines its function, any change
or abrogation of the tertiary structure will alter its activity
•
Denaturation of proteins can usually be caused by two key
conditions – temperature and pH.
Denaturation

74. •Temperature
•High levels of thermal energy may disrupt the hydrogen
bonds that hold the protein together
•As these bonds are broken, the protein will begin to
unfold and lose its capacity to function as intended
•Temperatures at which proteins denature may vary, but
most human proteins function optimally at body
temperature (~37ºC)
Denaturation

75. • pH
• Amino acids are zwitterions, neutral molecules possessing both
negatively (COO–) and positively (NH3
+) charged regions
• Changing the pH will alter the charge of the protein, which in
turn will alter protein solubility and overall shape
• All proteins have an optimal pH which is dependent on the
environment in which it functions (e.g. stomach proteins require
an acidic environment to operate, whereas blood proteins
function best at a neutral pH)
Denaturation

76. • Proteins are a very diverse class of compounds and may serve a
number of different roles within a cell, including:
Structure
• Collagen: A component of the connective tissue of animals (most
abundant protein in mammals)
• Spider silk: A fiber spun by spiders and used to make webs (by
weight, is stronger than kevlar and steel)
Hormones
• Insulin: Protein produced by the pancreas and triggers a reduction
in blood glucose levels
• Glucagon: Protein produced by the pancreas that triggers an
increase in blood glucose levels
Immunity
• Immunoglobulins: Antibodies produced by plasma cells that are
capable of targeting specific antigens
Protein Functions

77. Transport
• Haemoglobin: A protein found in red blood cells that is responsible
for the transport of oxygen
• Cytochrome: A group of proteins located in the mitochondria and
involved in the electron transport chain
Sensation
• Rhodopsin: A pigment in the photoreceptor cells of the retina that is
responsible for the detection of light
Movement
• Actin: Thin filaments involved in the contraction of muscle fibres
• Myosin: Thick filaments involved in the contraction of muscle fibres
Enzymes
• Rubisco: An enzyme involved in the light independent stage of
photosynthesis
Protein Functions

78. Place one-two spatulas of the food sample into a test tube or 1 cm3 if
the sample is liquid. Add about 1 cm3 depth of water to the tube
and stir to mix.
• Add an equal volume of potassium hydroxide solution to the tube
and stir.
• Add two drops of copper sulfate solution and stir for two minutes.
• Record the colour of the solution.
• Proteins are detected using Biuret reagent.This turns to
purple colour when mixed with protein.
Biuret test for proteins
Video Link-
https://safeYouTube.net/w/hxbE

79. Thank You