CHAPTER –9

BIOMOLECULES
BIOMOLECULES:-
• All the organic compounds that we get from living tissues are called biomolecules. Although they also contain inorganic
compounds and elements. These are essential molecules inside the body, which are necessary for life processes. eg..
Amino acids, Proteins, carbohydrates, Nucleic Acids. Nucleotides etc.
• Biomolecules consists mainly of carbon and hydrogen with nitrogen, oxygen, sulphur, and phosphorus.
• There are four major classes of biomolecules: Carbohydrates, Lipids, Proteins, Nucleic acids.
• Other biomolecules:- Some heterocyclic compounds (N2 bases), Vitamins, hormones etc.

FUNCTIONS OF BIOMOLECULES:-
• Carbohydrates provide the body with source of fuel and energy, it aids in proper functioning of our brain, heart and
nervous, digestive and immune system. Deficiency of carbohydrates in the diet causes fatigue, poor mental function.
• Each protein in the body has specific functions, some proteins provide structural support, help in body movement, and
also defence against germs and infections. Proteins can be antibodies, hormonal, enzymes and contractile proteins.
• Lipids, the primary purpose of lipids in body are energy storage. Structural membranes are composed of lipids which
form a barrier and controls flow of material in and out of the cell. Lipid hormones, like sterols, help in mediating
communication between cells.
• Nucleic Acids are the DNA and RNA; they carry genetic information in the cell. They also help in synthesis of proteins,
through the process of translation and transcription.

METABOLITES:-
• Any substance produced during metabolism (digestion or other bodily chemical processes like breaking down food,
drugs, chemicals, or body tissue to create energy and materials for growth, reproduction, and health).
• The term metabolite may also refer to the product that remains after a drug is broken down (metabolized) by the
body.
• usually small molecules that can be intermediate or end products of metabolism
USES-
• Medicine
o Metabolites can be the products that remain after the body breaks down a medicine.
o Drug metabolites can be active, inactive, or toxic.
o Active metabolites are biochemically active and have therapeutic effects.
o inactive metabolites have neither a therapeutic nor toxic effect.
• Signaling
o Secondary metabolites can be used in signaling pathways.
o For example, the urea cycle uses metabolites to convert ammonia, a toxic substance, into urea, which is
less toxic and can be excreted through the kidneys.
• Healthcare
o Metabolites can be used in cosmetics, food supplements, and other compounds.
o For example, analyzing xenometabolomes in epidemiological studies can help determine a person's
metabolic phenotype and characterize their exposure to chemicals in their environment or occupation.

• Primary metabolites are microbial products produced continuously during the exponential phase of growth and are
involved in primary metabolic processes such as respiration and photosynthesis. A primary metabolite is a kind of
metabolite that is directly involved in normal growth, development, and reproduction

• Secondary metabolites are derived by pathways in which primary metabolites involve. A secondary metabolite is
not directly involved in those processes, but usually has an important ecological function.

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 Analysis of Biomolecules
To find out composition of organic and inorganic substances in living tissue is called analysis of biomolecules.

 
Compound Analysis Elemental Analysis
 
It gives the idea of organic and inorganic compounds composition in living It gives the idea of elements composition
tissue in living tissue.
 eg. %age of H2, Cl2, C etc.
 
Chemical Analysis Biological Analysis
 
Identification of fractional groups Identification of Biomolecules.
and aromatic compounds eg. Amino Acids, Nucleotides,
eg. –CHO, =CO, -COOH etc. Fatty Acid, Proteins etc.

Analysis of for Chemical Composition of Biomolecules


 
Chemical Analysis Ash Analysis
 
Take small amount of living tissue Take small amount of living tissue
 
Mix it with Tri-chloro acetic Acid (CCl3COOH) Burn it to dry
 
Make thick paste with the help of mortar and pestle Take dry weight
 
Oxidation of C→CO2
Filter it
Oxidation of H→H2O
  
Acid insoluble pellets
Acid Soluble (Filtrate) Remain will be Ash
(Retentate)
  
Molecule Size < 1000 dalton Molecule Size > 1000 dalton
Inorganic Compounds left for analysis
Contain Cytoplasm Contain Cell organelles
• Sugars (Saccharides) • Polysaccharides
• Amino Acids • Proteins
• Lipids • Nucleic Acids
• N2 Bases • Large sized Lipids
• Nucleosides
• Nucleotides
• Cytoplasm
Analysis of above substances Analysis of above substances

CARBOHYDRATES/ POLYSACCHARIDES/ SACCHARIDES

Long chains of sugars/ Saccharides.
Compounds of carbon, hydrogen and oxygen where the ration of oxygen is similar to that of water.
They are either polyhydroxy aldehydes or polyhydroxy ketones.
SIGNIFICANCE OF CARBOHYDRATES:-
• Good source of energy.
• Structural components of cell.
• Help to recognise cell by glycoproteins
• Matrix of cartilage.
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 • Synovial fluid of joints
• Vitrous humour of eye

What are the different types of carbohydrates?

There are three main types of carbohydrates:
• SUGARS.
• Simple carbohydrates (most basic form)
• Can be added to foods, such as the sugar in candy, desserts, processed foods, and regular soda.
• They also include the kinds of sugar found naturally in fruits, vegetables, and milk.
• STARCHES.
• Complex carbohydrates made up of lots of simple sugars strung together.
• Body needs to break down starches into sugars for energy.
• Eg- bread, cereal, pasta and certain vegetables, like potatoes, peas, and corn.
• FIBER.
• Also a complex carbohydrate.
• Body cannot break down most fibers, so eating foods with fiber can help you feel full and make you less likely
to overeat.
• Diets high in fiber have other health benefits.
• They may help prevent stomach or intestinal problems, such as constipation.
• They may also help lower cholesterol and blood sugar.
• Eg-food from plants, including fruits, vegetables, nuts, seeds, beans, and whole grains.

COMMON FOODS WITH CARBOHYDRATES INCLUDE:

• Grains, such as bread, noodles, pasta, crackers, cereals, and rice
• Fruits, such as apples, bananas, berries, mangoes, melons, and oranges
• Dairy products, such as milk and yogurt
• Legumes, including dried beans, lentils, and peas
• Snack foods and sweets, such as cakes, cookies, candy, and other desserts
• Juices, regular sodas, fruit drinks, sports drinks, and energy drinks that contain sugar
• Starchy vegetables, such as potatoes, corn, and peas
• Some foods don't have a lot of carbohydrates, such as meat, fish, poultry, some types of cheese, nuts, and oils.

SACCHARIDES-
Carbohydrate molecules that contain single, double, or multiple sugar molecules are called saccharides.
Saccharides are of two types:-

1. MONOSACCHARIDES:-
• These are simple sugars that are composed single unit of sugar of 3-7 carbon atoms.
• They cannot further hydrolysed.
• They have a free aldehyde or ketone group, which acts as reducing agents and are known as reducing sugars.
• On the basis of carbon atom present in them they can be Triose sugar, Tetrose sugar, Pentose sugar, Hexose
sugar, Heptos sugar.
• eg. Ribose (Pentose Sugar), Glucose (Hexose Sugar) Monosaccharides - Glucose, galactose, glycerose,
erythrose, ribose, ribulose, fructose.

2. OLIGOSACCHARIDES:-
• They are composed of two or more than two molecule (2-10) of monosaccharides.
• Glycosidic bonds shared between two monosaccharide units.
• On the basis of presence of saccharides molecules they may be
o Disaccharides / trisaccharides / Tetrasaccharides/ Pentasaccharides and so on.

• DISACCHARIDES :-
o These are made of two monosaccharides. These are sweet, crystalline and water soluble
substances.
o e.g. Maltose, lactose, sucrose, raffinose, stachyose.
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 • TYPES OF OLIGOSACCHARIDES-
o Simple Oligosaccharides- They are composed of same molecules of monosaccharides.
o Complex Oligosaccharides- They are composed of different molecules of monosaccharides.

Disaccharides are composed of two monosaccharide units linked together by a glycosidic bond.

Monosaccharides and oligosaccharides, along with their derivatives, are important molecules with various biological
properties, including anticancer, antiviral, insecticidal, antimicrobial, and antioxidant activity.
3. Polysaccharides:-
• Polymers of monosaccharides.
• Un-sweet and complex carbohydrates.
• Insoluble in water
• Not found in crystalline form.
• Eg. Glycogen, Inulin, glycogen Cellulose, Pectin, Hemi cellulose, Lignin, Chitin, Murein, Hyaluronic acid,
Heparin, Gums, Mucilages

Different between monosaccharides, oligosaccharides and Polysaccharides

S. No. Character Monosaccharides Oligosaccharides Polysaccharides
1 No. of sugar molecules 1 2-10 More than 10
2 Glycoside bond Absent Present Present
3 Molecular Weight Low Moderate High
4 Taste Sweet Minimally sweet taste No taste
5 Solubility Soluble Soluble Insoluble
6 Nature Always reducing sugar May or may not be Always non-reducing sugar
7 Example Glucose, fructose Galactose, Sucrose, Maltose Starch, Glycogen, Dextrin Cellulose

Types of polysaccharides on the basis of the arrangement of sugar

• SIMPLE POLYSACCHARIDES:-
o Linear chain of sugar
o Eg-Amylose
• COMPLEX POLYSACCHARIDES:-
o Branched chains of sugar.
o Eg Amylopectin, Glucogen, Cellulose
o Cellulose is a complex polysaccharide, or complex carbohydrate, made up of hundreds to thousands of
glucose units linked together in a linear chain. This makes it a complex carbohydrate because it has more
than two units of sugar linked together.

Types of polysaccharide on the basis of types of sugar

• Homopolysaccharides:-
o Homopolysaccharides are chemical compounds that are composed of a single type of monomer.
o eg. Starch, Cellulose and Glycogen. Cellulose is a linear polymer of glucose.
o It is the most abundant carbohydrate in nature or biosphere.
o Cellulose is basic structural component of plant cell walls. It makes up about 33% of all vegetable matter,
including 90% of cotton and 50% of wood.
o Cellulose also plays an important role in human diet, even though humans cannot digest it.

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 • Heteropolysaccharides:-
o Heteropolysaccharides are polysaccharides that are made out of two or more different monosaccharides.
o eg. chondroitin sulfate, hyaluronic acid and heparin, inulin, peptidoglycan, Agarose
o Chondroitin sulfate is an important component of cartilage.
o Hyaluronic acid is found in the fluid of joints and in vitreous humor of the eye.

LIPIDS
• These are long chain compounds of C, H and O where the number of Oxygen atoms are very less (O<H).
• General Formula- COOH-(CH2)-R
• Lipid molecules hold a large amount of energy and are energy storage molecules.
• These generally esters of fatty acids
• Building blocks of biological membranes.
• Most of the lipids have a polar head and non-polar tail.
• Water insoluble.
• Soluble in polar organic compounds.
• Lipids present in biological membranes are of three classes based on the type of hydrophilic head present
• e.g. Fatty Acids, oils, wax, cutin, suberin, phospholipids, glycolipids, steroids, cholesterol, terpenes, hard fats etc.

Types of Fatty Acids:-

• SATURATED FATTY ACIDS- Without double bonds
• UNSATURATED FATTY ACIDS- With double or triple bonds

Esterification:- Removal of (H2O) by addition of alcohol from fatty acids (acid)

AMINO ACIDS
• These are substitute of methane where R (functional Group) specify the Amino acids.
• Amino acids binds together to form proteins .
• They act as Chemical messengers (neurotransmitters) in the nervous system.
• They are amphoteric in nature.
• Sulphur containing Amino Acids Methionine, Cysteine, Cystine (MCC-Melbourne Cricket Club)
• eg. Glycine R=H, Alanine R=CH3, Serine R=CH3OH

• ESSENTIAL OR VITAL AMINO ACIDS:-

There are 10 essential (vital), amino acids, which are necessary for the human life and health but cannot be
produced in our body so need to get them from foods. (TT HALLIM VP)

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 • CONDITIONALLY ESSENTIAL AMINO ACIDS:-
These amino acids can be synthesized in your body, but in certain circumstances, like young age, illness or hard
exercise, we need to get them in additional amounts from foods to meet the body requirements for them.
Ornithine is also considered conditionally essential amino acid, but it does not form proteins

• NONESSENTIAL AMINO ACIDS:-

These amino acids can be synthesized in your body from other amino acids, glucose and fatty acids, so you do
not need to get them from foods

• There are6 groups of 20 natural Amino Acids (Principal Protein Amino Acids of living tissue)

S.No. Groups/ Category Nos. Amino Acids Abbreviation

1 Glycine Gly
2 Alanine Ala
Neutral
A 3 Valine Val
(GAVLI)
4 Leucine Leu
5 Isoleucine Ile
6 Aspartic Acid Asp
Acidic 7 Asparagine Asn (amide)
B
(A2G2) 8 Glutamic Acid Glu
9 Glutamine Gln (amide)
Basic 10 Arginine Arg
C
(AL) 11 Lysine Lyc
Sulphur Containing 12 Cysteine Cys
D
(CM) 13 Methionine Met
Alcoholic 14 Serine Ser
E
(ST) 15 Threonine Thr
16 Histidine His
17 Phenyl Alanine Phe
Aromatic
F 18 Proline Pro
(HP2T2)
19 Tyrosine Tyr
20 Tryptophane Try

PROTEINS
• Proteins are heteropolymers of strings of amino acids.
• Amino acids are joined together by the peptide bond
• Peptide bond is formed in between the carboxyl group and the amino group of successive amino acids.
• Proteins are formed from 20 different natural amino acids.
• They can act as enzymes.
• Responsible for different types of traits in the body.
• All enzymes are proteins but all proteins are not enzymes.
• Collagen is the most abundant protein found in animals.
• RuBisCO (Ribulose-1,5-bisphosphate carboxylase oxygenase) is the most abundant protein in biosphere which is
an enzyme that catalyzes the first major step of carbon fixation in the Calvin cycle.

There are four levels of protein structure:

1. Primary structure of Protein - Here protein exist as long chain of amino acids arranged in a particular
sequence. They are non-functional proteins.
2. Secondary structure of protein - The long chain of proteins are folded and arranged in a helix shape, where the
amino acids interact by the formation of hydrogen bonds. This structure is called the pleated sheet. Example: silk
fibres.
3. Tertiary structure of protein - Long polypeptide chains become more stabilizes by folding and coiling, by the
formation of ionic or hydrophobic bonds or disulphide bridges, these results in the tertiary structure of protein.

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 4. Quaternary structure of protein - When a protein is an assembly of more than one polypeptide or subunits of its
own, this is said to be the quaternary structure of protein. Example: Haemoglobin, insulin.

Peptide Bond Structure:- It formed by elimination of H2O molecule between amino acids.
• N-Terminal:-Amino acid of Left side of Chain
• C- Terminal:- Amino acid of Right side of Chain

TYPES OF PROTEINS-
Fibrous proteins-
• Insoluble in water, weak acids and weak bases
• Soluble in strong acids and alkalis
• These are highly resistant to digestion by enzymes and are extremely tensile.
• eg. collagen, elastin, keratin, silk etc.
Globular proteins-
• Soluble in water, acids and bases
• eg. myoglobin, haemoglobin, casein, insulin, etc

NUCLEIC ACIDS
Nucleic Acids:- Nucleic acids are made of chain of polymer of nucleotides.
Types of Nucleic Acid:- RNA and DNA
• RNA:- made up of one chain of Polynucleotide
• DNA:- made up of two chains of Polynucleotide which are held together by hydrogen bonds.

Difference Between DNA and RNA:-

DNA RNA
Deoxyribonucleic Acid Ribonucleic Acid
Long-term storage of genetic information; transmission of Used to transfer the genetic code from the nucleus to the
genetic information to make other cells and new ribosomes to make proteins. RNA is used to transmit genetic
organisms. information in some organisms.
DNA is a double-stranded molecule consisting of a long RNA usually is a single-strand helix consisting of shorter
chain of nucleotides. chains of nucleotides.
Deoxyribose sugar ribose sugar
adenine, guanine, cytosine, thymine bases adenine, guanine, cytosine, uracil bases
DNA is self-replicating. RNA is synthesized from DNA
AT (adenine-thymine) & GC (guanine-cytosine) AU (adenine-uracil) & GC (guanine-cytosine)
The C-H bonds in DNA make it fairly stable. The O-H bond in the ribose of RNA makes the molecule more
reactive, compared with DNA.
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 N2 Bases
A carbon and nitrogen compound with heterocyclic rings and has the basic properties.
↓ ↓
Purines Pyrimidines

↓ ↓ ↓ ↓ ↓
Adenine Guanine Thymine Uracil Cytosine
Both in RNA & DNA Both in RNA & DNA In DNA In RNA Both in RNA & DNA

Nucleosides = N2 Bases + Pentose sugar

Nucleotides = N2 Bases + Pentose sugar + PO4--
↑
Nucleotides = Nucleosides + PO4--

METABOLISM
Sum total of all the reaction in living body is called metabolism.
It includes two processes.
Metabolism=Catabolism + Anabolism
Catabolism:-
• Breakdown process
• Bond breaking
• Energy released
• Exothermic Reaction
• A⟶ B + C + Energy
Anabolism:-
• Synthesis or formation process
• Bond formation
• Energy utilized or required
• Endothermic Reaction
• A + B + Energy⟶ C
LIVING STATE:-
• Possible due to presence of metabolism
• Non-equilibrium steady state because living body perform formation and breakdown continuously depending upon
requirement and conditions.
METABOLIC PATHWAY:-
• The steps involve the formation of product from the substrate is metabolic pathway.
• eg. Glycolysis is 10 step process. (Glucose ⟶ 2 Pyruvic Acid Molecules + Energy)
ENZYMES:-
• Also called biological catalyst.
• Bond formation
• Energy utilized or required
Similarities between Biological and Inorganic catalysts
• Both remain unchanged at the end of reaction
• Both can be re-utilized.
• Both cannot initiate the reaction but can change the rate of reaction by reducing activation energy.

Dissimilarities between Biological and Inorganic catalysts

Nos. Biological Catalysts Inorganic Catalysts
1 Enzymes are proteins These are inorganic compounds
2 Have complex structure Have simple structure
3 Heavy weight molecules Lightweight molecules
4 Reaction Specific Can be used for many reactions
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CLASSIFICATION OF ENZYMES:-

• Oxidoreductase/dehydrogenases :
Catalyse oxidoreduction between 2 substrates.
A (oxidised) + B (reduced) ⟶ A (reduced) + B(oxidised)

• Transferases : Catalyse transfer of a group between a pair of substrates.

A-G + B ⟶ A + B-G

• Hydrolases : Catalyse hydrolysis of ester, ether, peptide, glycosidic, C-C, P-N bonds.
A + H2O ⟶ B + C
e.g . C12H22O11 + H2O ⟶ C6H12O6 + C6H12O6

• Lyases : Catalyse removal of groups from substrates by mechanisms other than hydrolysis.
X-C-C-Y ⟶ X-Y + C=C

• Isomerases :
Catalyse inter-conversion of optical, geometric or positional isomers.
It does not change molecular formula.
It only changes spatial arrangement of atoms in a molecule.

• Ligases :
Catalyse linking together of 2 compounds.
They are used to make larger molecules by covalent bond formation

AA1- AA2- AA3- AA4- ------ AAn

Holoenzyme (Conjugated Enzyme)

(Biochemically active compound formed by the combination of an enzyme with a coenzyme)

 
Apoenzyme Co-factor
Protein portion of enzyme is called
Non-protein constituents found to the enzyme to make it catalytically active
apoenzyme.
|
  
Prosthetic groups Co-enzymes Metal ions
Organic compounds loosely bound with
Required for enzyme activity.
Organic compounds tightly bound to apoenzyme.
Form coordination bond between the
apoenzyme. Attached only at the time of requirements
active site of enzyme and substrate.
e.g., Haem in Globin protein only.
eg. Zn for carboxypeptidase
e.g., NAD, NADP.

Mechanism of enzymatic action: -

An enzyme attracts substrates to its active site, catalyzes the chemical reaction by which products are formed, and then allows
the products to dissociate (separate from the enzyme surface). The combination formed by an enzyme and its substrates is
called the enzyme–substrate complex.

The activation energy is the energy required to start a reaction. Enzymes are proteins that bind to a molecule, or substrate, to
modify it and lower the energy required to make it react. The rate of reaction increases if the activation energy decreases.

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Transition State:-
It is the state corresponding to the highest energy along the reaction coordinate. It has more free energy in comparison to the
substrate or product; thus, it is the least stable state.

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