BIOMOLECULES – CLASS 12 CHSE
FULL LONG NOTES (EASY + EXAM-ORIENTED)
INTRODUCTION
Biomolecules are chemical compounds present in living organisms. They include carbohydrates,
proteins, lipids, nucleic acids, vitamins, hormones, and enzymes. These molecules help in structure,
function, energy storage, and regulation of life processes.
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1. CARBOHYDRATES
Carbohydrates are polyhydroxy aldehydes or ketones or compounds that produce them on hydrolysis.
General formula: Cx(H2O)y.
CLASSIFICATION:
A) Monosaccharides
- Simplest sugars, cannot be hydrolyzed further.
- Types: Trioses, Pentoses, Hexoses.
- Examples:
* Glucose (aldohexose) – most important energy source.
* Fructose (ketohexose) – sweetest natural sugar.
* Ribose – present in RNA.
Structure of Glucose:
- Exists in open-chain and cyclic (α and β forms).
- Shows mutarotation.
B) Disaccharides
- Formed from two monosaccharides linked by glycosidic bond.
Examples:
- Sucrose = Glucose + Fructose (non-reducing)
- Maltose = Glucose + Glucose (reducing)
- Lactose = Glucose + Galactose (reducing)
, C) Polysaccharides
- Long chains of monosaccharides.
Examples:
- Starch – storage sugar in plants.
- Glycogen – storage sugar in animals.
- Cellulose – structural sugar in plants.
BIOLOGICAL FUNCTIONS
- Instant energy (glucose)
- Energy storage (glycogen)
- Structural (cellulose in plants, chitin in insects)
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2. PROTEINS
Proteins are polymers of amino acids linked by peptide bonds.
AMINO ACIDS
- Contain amino group (NH2), carboxyl group (COOH), H atom, and R-group.
- 20 amino acids occur naturally.
- Exist as zwitter ions in aqueous solution.
PEPTIDE BOND
Bond formed between –COOH of one amino acid and –NH2 of another, releasing water.
LEVELS OF PROTEIN STRUCTURE:
1. Primary: Linear chain of amino acids.
2. Secondary: α-helix and β-pleated sheet (hydrogen bonding).
3. Tertiary: 3D folding (globular proteins).
4. Quaternary: Combination of polypeptide chains.
TYPES OF PROTEINS:
FULL LONG NOTES (EASY + EXAM-ORIENTED)
INTRODUCTION
Biomolecules are chemical compounds present in living organisms. They include carbohydrates,
proteins, lipids, nucleic acids, vitamins, hormones, and enzymes. These molecules help in structure,
function, energy storage, and regulation of life processes.
---------------------------------------------------------
1. CARBOHYDRATES
Carbohydrates are polyhydroxy aldehydes or ketones or compounds that produce them on hydrolysis.
General formula: Cx(H2O)y.
CLASSIFICATION:
A) Monosaccharides
- Simplest sugars, cannot be hydrolyzed further.
- Types: Trioses, Pentoses, Hexoses.
- Examples:
* Glucose (aldohexose) – most important energy source.
* Fructose (ketohexose) – sweetest natural sugar.
* Ribose – present in RNA.
Structure of Glucose:
- Exists in open-chain and cyclic (α and β forms).
- Shows mutarotation.
B) Disaccharides
- Formed from two monosaccharides linked by glycosidic bond.
Examples:
- Sucrose = Glucose + Fructose (non-reducing)
- Maltose = Glucose + Glucose (reducing)
- Lactose = Glucose + Galactose (reducing)
, C) Polysaccharides
- Long chains of monosaccharides.
Examples:
- Starch – storage sugar in plants.
- Glycogen – storage sugar in animals.
- Cellulose – structural sugar in plants.
BIOLOGICAL FUNCTIONS
- Instant energy (glucose)
- Energy storage (glycogen)
- Structural (cellulose in plants, chitin in insects)
---------------------------------------------------------
2. PROTEINS
Proteins are polymers of amino acids linked by peptide bonds.
AMINO ACIDS
- Contain amino group (NH2), carboxyl group (COOH), H atom, and R-group.
- 20 amino acids occur naturally.
- Exist as zwitter ions in aqueous solution.
PEPTIDE BOND
Bond formed between –COOH of one amino acid and –NH2 of another, releasing water.
LEVELS OF PROTEIN STRUCTURE:
1. Primary: Linear chain of amino acids.
2. Secondary: α-helix and β-pleated sheet (hydrogen bonding).
3. Tertiary: 3D folding (globular proteins).
4. Quaternary: Combination of polypeptide chains.
TYPES OF PROTEINS:
