Class 11 Biology - Biomolecules

Key Concepts

Analysis of Chemical Composition

Organic Compounds: Living tissue (vegetable or liver) is ground in trichloroacetic acid (Cl₃CCOOH). Filtering through cheesecloth yields two fractions:
- Acid-soluble pool (Filtrate): Contains thousands of small organic compounds (micromolecules).
- Acid-insoluble fraction (Retentate): Contains macromolecules like proteins, polysaccharides, and nucleic acids.
Inorganic Elements: Obtained by burning tissue to "ash." Elements like Calcium, Magnesium, Sodium, and compounds like sulphate and phosphate are identified.
Biomolecules: All carbon compounds obtained from living tissues.

Amino Acids

Structure: Organic compounds containing an amino group (-NH₂) and an acidic carboxyl group (-COOH) on the same α-carbon. They are substituted methanes.
R Group: The variable group determines the amino acid.
- Glycine (R = H)
- Alanine (R = -CH₃)
- Serine (R = -CH₂OH)
Types: 20 types occur in proteins. Can be acidic (Glutamic acid), basic (Lysine), neutral (Valine), or aromatic (Tyrosine, Phenylalanine, Tryptophan).
Zwitterion: In different pH solutions, the structure changes due to the ionizable nature of amino and carboxyl groups.

Lipids

Generally water-insoluble.
Fatty Acids: Carboxyl group attached to an R group (1-19 carbons). Palmitic acid (16C), Arachidonic acid (20C). Can be saturated (no double bonds) or unsaturated.
Glycerol: Trihydroxy propane.
Triglycerides: Glycerol esterified with three fatty acids.
Phospholipids: Lipids with a phosphorus and a phosphorylated organic compound (e.g., Lecithin in cell membranes).

Nitrogen Bases, Nucleosides, and Nucleotides

Nitrogen Bases: Purines (Adenine, Guanine) and Pyrimidines (Cytosine, Uracil, Thymine).
Nucleosides: Nitrogen base + Sugar (e.g., Adenosine, Guanosine, Uridine, Cytidine).
Nucleotides: Nucleoside + Phosphate group (e.g., Adenylic acid, Guanylic acid). These are the building blocks of nucleic acids (DNA and RNA).

Primary and Secondary Metabolites

Primary Metabolites: Have identifiable functions and roles in normal physiological processes (e.g., amino acids, sugars).
Secondary Metabolites: Produced in plants, fungi, and microbes; functions are not always clear but useful to human welfare (e.g., alkaloids, rubber, antibiotics, spices, pigments).

Biomacromolecules

Found in the acid-insoluble fraction with molecular weights > 10,000 Da (except lipids).
Proteins: Heteropolymers of amino acids. Linear chains linked by peptide bonds.
- Collagen: Most abundant protein in the animal world.
- RuBisCO: Most abundant protein in the whole biosphere.
Polysaccharides: Long chains of sugars.
- Cellulose: Homopolymer of glucose; found in plant cell walls.
- Starch: Energy store in plants; forms helical secondary structures.
- Glycogen: Energy store in animals.
- Chitin: Complex polysaccharide in arthropod exoskeletons.
Nucleic Acids: Polynucleotides (DNA/RNA).

Structure of Proteins

Primary Structure: The sequence/positional information of amino acids.
Secondary Structure: Folding of the thread into forms like the α-helix (right-handed) or β-pleated sheets.
Tertiary Structure: 3D folding of the protein chain upon itself; essential for biological activity.
Quaternary Structure: Assembly of multiple polypeptide subunits (e.g., Haemoglobin: 2α and 2β subunits).

Enzymes

Nature: Almost all are proteins. Some are nucleic acids (Ribozymes).
Mechanism: Have an 'active site' (crevice) where the substrate fits. They lower the Activation Energy required for a reaction.
Catalytic Cycle:
1. Substrate binds to active site.
2. Enzyme alters shape (induced fit).
3. Bonds broken/made; ES complex forms transition state.
4. Products released; enzyme ready for next cycle.
Factors Affecting Activity:
- Temperature & pH: Each has an optimum. High temp denatures proteins.
- Substrate Concentration: Rate increases until Vmax is reached (enzyme saturation).
- Inhibitors: Chemicals that shut off activity. Competitive inhibitors resemble the substrate (e.g., Malonate inhibits Succinic dehydrogenase).

Competitive Inhibition Because the inhibitor competes with the substrate for the active site, increasing the substrate concentration can eventually overcome the inhibition and reach the same Vmax. This is used to control bacterial pathogens.

Classification:
1. Oxidoreductases 2. Transferases 3. Hydrolases 4. Lyases 5. Isomerases 6. Ligases.
Co-factors: Non-protein constituents making the enzyme active.
- Apoenzyme: Protein portion.
- Prosthetic groups: Tightly bound (e.g., Haem).
- Co-enzymes: Transiently bound organic compounds (e.g., NAD, NADP containing Niacin).
- Metal Ions: e.g., Zinc for carboxypeptidase. peptidase.

Key Concepts

Organic Compounds: Living tissue (vegetable or liver) is ground in trichloroacetic acid (Cl₃CCOOH). Filtering through cheesecloth yields two fractions:

Acid-soluble pool (Filtrate): Contains thousands of small organic compounds (micromolecules).
Acid-insoluble fraction (Retentate): Contains macromolecules like proteins, polysaccharides, and nucleic acids.

Inorganic Elements: Obtained by burning tissue to "ash." Elements like Calcium, Magnesium, Sodium, and compounds like sulphate and phosphate are identified.

Biomolecules: All carbon compounds obtained from living tissues.

Structure: Organic compounds containing an amino group (-NH₂) and an acidic carboxyl group (-COOH) on the same α-carbon. They are substituted methanes.

R Group: The variable group determines the amino acid.

Glycine (R = H)
Alanine (R = -CH₃)
Serine (R = -CH₂OH)

Types: 20 types occur in proteins. Can be acidic (Glutamic acid), basic (Lysine), neutral (Valine), or aromatic (Tyrosine, Phenylalanine, Tryptophan).

Zwitterion: In different pH solutions, the structure changes due to the ionizable nature of amino and carboxyl groups.

Generally water-insoluble.

Fatty Acids: Carboxyl group attached to an R group (1-19 carbons). Palmitic acid (16C), Arachidonic acid (20C). Can be saturated (no double bonds) or unsaturated.

Glycerol: Trihydroxy propane.

Triglycerides: Glycerol esterified with three fatty acids.

Phospholipids: Lipids with a phosphorus and a phosphorylated organic compound (e.g., Lecithin in cell membranes).

Nitrogen Bases: Purines (Adenine, Guanine) and Pyrimidines (Cytosine, Uracil, Thymine).

Nucleosides: Nitrogen base + Sugar (e.g., Adenosine, Guanosine, Uridine, Cytidine).

Nucleotides: Nucleoside + Phosphate group (e.g., Adenylic acid, Guanylic acid). These are the building blocks of nucleic acids (DNA and RNA).

Primary Metabolites: Have identifiable functions and roles in normal physiological processes (e.g., amino acids, sugars).

Secondary Metabolites: Produced in plants, fungi, and microbes; functions are not always clear but useful to human welfare (e.g., alkaloids, rubber, antibiotics, spices, pigments).

Found in the acid-insoluble fraction with molecular weights > 10,000 Da (except lipids).

Proteins: Heteropolymers of amino acids. Linear chains linked by peptide bonds.

Collagen: Most abundant protein in the animal world.
RuBisCO: Most abundant protein in the whole biosphere.

Polysaccharides: Long chains of sugars.

Cellulose: Homopolymer of glucose; found in plant cell walls.
Starch: Energy store in plants; forms helical secondary structures.
Glycogen: Energy store in animals.
Chitin: Complex polysaccharide in arthropod exoskeletons.

Nucleic Acids: Polynucleotides (DNA/RNA).

Primary Structure: The sequence/positional information of amino acids.

Secondary Structure: Folding of the thread into forms like the α-helix (right-handed) or β-pleated sheets.

Tertiary Structure: 3D folding of the protein chain upon itself; essential for biological activity.

Quaternary Structure: Assembly of multiple polypeptide subunits (e.g., Haemoglobin: 2α and 2β subunits).

Nature: Almost all are proteins. Some are nucleic acids (Ribozymes).

Mechanism: Have an 'active site' (crevice) where the substrate fits. They lower the Activation Energy required for a reaction.

Catalytic Cycle:

Substrate binds to active site.
Enzyme alters shape (induced fit).
Bonds broken/made; ES complex forms transition state.
Products released; enzyme ready for next cycle.

Factors Affecting Activity:

Temperature & pH: Each has an optimum. High temp denatures proteins.
Substrate Concentration: Rate increases until Vmax is reached (enzyme saturation).
Inhibitors: Chemicals that shut off activity. Competitive inhibitors resemble the substrate (e.g., Malonate inhibits Succinic dehydrogenase).

Classification:

Oxidoreductases 2. Transferases 3. Hydrolases 4. Lyases 5. Isomerases 6. Ligases.

Co-factors: Non-protein constituents making the enzyme active.

Apoenzyme: Protein portion.
Prosthetic groups: Tightly bound (e.g., Haem).
Co-enzymes: Transiently bound organic compounds (e.g., NAD, NADP containing Niacin).
Metal Ions: e.g., Zinc for carboxypeptidase. peptidase.

Class 11 Biology - Biomolecules

Class 11 Biology - Biomolecules

Notes

Key Concepts

Analysis of Chemical Composition

Amino Acids

Lipids

Nitrogen Bases, Nucleosides, and Nucleotides

Primary and Secondary Metabolites

Biomacromolecules

Structure of Proteins

Enzymes

On this page

Class 11 Biology - Biomolecules

Class 11 Biology - Biomolecules

Notes

Key Concepts

Analysis of Chemical Composition

Amino Acids

Lipids

Nitrogen Bases, Nucleosides, and Nucleotides

Primary and Secondary Metabolites

Biomacromolecules

Structure of Proteins

Enzymes

On this page