Grade 12
  1. Solid state  1.1. Classification of solids  1.2. Crystal Lattice and Unit Cell  1.3. Packing Efficiency  1.4. Density of unit cell  1.5. Imperfections in solids (point and line defects)  1.6. Electrical Properties of Solids (Conductors, Insulators and Semiconductors)  1.7. Magnetic Properties of Solids (Diamagnetic, Paramagnetic and Ferromagnetic Materials)
  2. Solution  2.1. Types of Solutions (Homogeneous and Heterogeneous)  2.2. Expressing concentration of solutions (mass %, volume %, molarity, molality, normality, mole fraction)  2.3. Solubility of solids and gases in liquids (Henry's law)  2.4. Raoult's Law and Ideal and Non-Ideal Solutions  2.5. Syndrome properties  2.6. Abnormal molar mass and Van't Hoff factor
  3. Electrochemistry  3.1. Electrochemical cells (galvanic and electrolytic cells)  3.2. Galvanic cell and EMF of the cell  3.3. Standard electrode potential and electrochemical series  3.4. Nernst equation and its applications  3.5. Conductivity and electrolytic cells (specific, molar and equivalent conductivity)  3.6. Kohlrausch's law and its applications  3.7. Batteries (primary and secondary cells)  3.8. Corrosion and its prevention
  4. Chemical kinetics  4.1. Rate of chemical reaction  4.2. Factors affecting the reaction rate (concentration, temperature, catalyst, surface area)  4.3. Order and molecularity of the reaction  4.4. Integrated Rate Equations (Zero, First and Second Order)  4.5. Half-life of a reaction  4.6. Collision theory and activation energy  4.7. Arrhenius equation and its applications
  5. Surface chemistry  5.1. Adsorption and its types (Physicosorption and Chemisorption)  5.2. Catalysis and its types (homogeneous and heterogeneous)  5.3. Colloids and their properties (Tyndall effect, Brownian motion, coagulation)  5.4. Emulsions and gels  5.5. Applications of Colloids
  6. General principles and processes of separation of elements  6.1. Presence of metals and minerals  6.2. Concentration of ores (gravity separation, froth flotation, magnetic separation)  6.3. Extraction of raw metals (roasting, calcination, reduction)  6.4. Thermodynamic and electrochemical principles of metallurgy  6.5. Refining of metals
  7. P-block elements  7.1. Group 15 elements (nitrogen and phosphorus)  7.2. Group 16 Elements (Oxygen, Sulphur and their Compounds)  7.3. Group 17 Elements (Halogens and their Compounds)  7.4. Group 18 Elements  7.5. Properties and Trends in p-Block Elements  7.6. Important compounds of p-block elements (ammonia, phosphine, sulphuric acid, hydrochloric acid)  7.7. Interhalogen compounds and their applications
  8. d-block and f-block elements  8.1. General Properties of Transition Metals  8.2. Properties of Inner Transition Metals (Lanthanoids and Actinoids)  8.3. Lanthanoid and actinoid contractions  8.4. Coordination Chemistry of d-Block Elements
  9. Coordination compounds  9.1. Werner's theory and modern concepts  9.2. Coordination number and type of ligand  9.3. Nomenclature of Coordination Compounds  9.4. Isomerism (geometrical and optical) in coordination compounds  9.5. Bonding in Coordination Compounds (Valence Bond Theory and Crystal Field Theory)  9.6. Stability and applications of coordination compounds in medicine and industry
  10. Haloalkanes and haloarenes  10.1. Classification and nomenclature of haloalkanes and haloarenes  10.2. Physical and Chemical Properties of Haloalkanes and Haloarenes  10.3. Mechanism of Nucleophilic Substitution Reactions (SN1 and SN2)  10.4. Uses and environmental effects (ozone depletion, CFCs)
  11. Alcohol, phenol and ether  11.1. Structure and classification of alcohols, phenols and ethers  11.2. Preparation and properties of alcohols  11.3. Preparation and properties of phenol  11.4. Preparation and properties of ethers  11.5. Chemical Reactions and Uses
  12. Aldehydes, ketones and carboxylic acids  12.1. Structure and nomenclature in aldehydes, ketones and carboxylic acids  12.2. Preparation and properties of aldehydes and ketones  12.3. Chemical reactions in aldehydes, ketones and carboxylic acids (nucleophilic addition, oxidation and reduction)  12.4. Preparation and Properties of Carboxylic Acids  12.5. Chemical Reactions and Uses of Carboxylic Acids
  13. Nitrogen-containing organic compounds  13.1. Amines (classification, structure, basicity)  13.2. Preparation and properties of amines  13.3. Reactions of Amines (Diazotization, Carbylamine Reaction)  13.4. Diazonium salts and their applications in paint industry
  14.1. Carbohydrates (classification and properties)  14.2. Proteins (Structure and Function)  14.3. Enzymes (Mechanism and Function)  14.4. Nucleic acids (DNA and RNA)  14.5. Vitamins and hormones
  15. Polymer  15.1. Classification of Polymers (Addition, Condensation, Copolymers)  15.2. Types of polymerization (free radical, ionic, condensation)  15.3. Important Polymers and Their Uses  15.4. Biodegradable and non-biodegradable polymers
  16. Chemistry in Everyday Life  16.1. Drugs and their classification (analgesics, antipyretics, antibiotics, antacids)  16.2. Chemicals in food and cosmetics (preservatives, artificial sweeteners, antioxidants)  16.3. Cleaning agents and detergents (soaps, synthetic detergents, surfactants)  16.4. Environmental Chemistry (Pollution, Green Chemistry, Sustainable Chemistry)

Grade 12 ↓


Proteins (Structure and Function)


Proteins are large, complex molecules that play many important roles in living organisms. They are essential components of all living cells, and are involved in nearly every process within biological systems. Understanding the structure and function of proteins is fundamental in the fields of chemistry, biology, and medicine.

1. What are proteins?

Proteins are biomolecules composed of amino acid chains. These chains are folded into specific three-dimensional structures that determine the protein's function. Proteins are known for their versatility, contributing to structural integrity, transport, metabolism, regulation, and catalysis in cells.

2. Basic structure of proteins

The basic structure of a protein can be described at different levels:

2.1 Primary structure

The primary structure of a protein is its unique sequence of amino acids. This sequence is determined by genetic information encoded in DNA. Amino acids are linked by peptide bonds to form a polypeptide chain.

HOOC-CHR-NH2 | | Amino Carboxyl Group Group

Example: The primary structure of a protein may look like the following simplified form:

Glycine-Valine-Alanine-Leucine

2.2 Secondary structure

The secondary structure of proteins refers to the local folded structures that form within the polypeptide due to interactions between the backbone atoms. The most common secondary structures are the alpha helix and the beta pleated sheet.

Alpha Helix: This structure is a right-handed coil where each backbone -NH group four amino acids ago forms a hydrogen bond with the backbone -C=O group.

Turns of the helix ////////

Beta pleated sheet: In this structure, two or more segments of the polypeptide chain line up next to each other, forming a sheet-like structure by hydrogen bonds.

Interconnected chains ||||||||||||

2.3 Tertiary structure

Tertiary structure is the overall three-dimensional structure of a single protein molecule. The spatial arrangement is stabilized by various interactions, including hydrogen bonds, disulfide bonds, ionic interactions, and hydrophobic packing.

Interactions include:

  • Hydrogen bond - a weak bond between an electronegative atom and a hydrogen atom bonded to another electronegative atom.
  • Disulfide bonds - strong covalent bonds formed between two sulfur atoms of cysteine residues.
  • Ionic interactions - attraction between oppositely charged side chains.
  • Hydrophobic interactions - nonpolar side chains group away from water.

2.4 Quaternary structure

Quaternary structure refers to the assembly of several polypeptide chains into a functional protein complex. Each peptide chain is called a subunit. For example, hemoglobin has a quaternary structure consisting of four subunits.

Subunit structure _______ _______ | | | | | Sub1 | | Sub2 | |_______| |_______| _______ _______ | | | | | Sub3 | | Sub4 | |_______| |_______|

3. Functions of proteins

Proteins perform a variety of functions in biological organisms. Here are some of the main functions:

3.1 Structural proteins

These proteins provide support and shape to cells. An example is collagen, which is found in skin, bones, and connective tissue. Another example is keratin, which is found in hair and nails.

Example: Collagen provides tensile strength to tissues.

3.2 Enzymes

Enzymes are proteins that act as biological catalysts. They speed up chemical reactions that occur in the body without being consumed in the process. For example, amylase is an enzyme that helps digest carbohydrates.

Example: Amylase acts as a catalyst to break down starch into sugars.

3.3 Transport proteins

Transport proteins are involved in the movement of substances across the cell membrane. Hemoglobin is a transport protein that carries oxygen in the blood.

Example: Hemoglobin carries oxygen from the lungs to other tissues.

3.4 Hormonal proteins

Hormones are regulatory proteins that control various bodily functions. Insulin is a hormone that regulates blood sugar levels.

Example: Insulin facilitates the absorption of glucose into cells.

3.5 Defense proteins

These proteins are involved in defending the body against germs. Antibodies are proteins that recognize and neutralize foreign invaders such as bacteria and viruses.

Example: Antibodies bind to antigens on pathogens and mark them for destruction.

3.6 Receptor proteins

Receptor proteins are located in the cell membrane and allow cells to communicate with their external environment. They bind signaling molecules such as hormones or neurotransmitters, thereby initiating a cellular response.

Example: Receptor proteins in nerve cells enable signaling between neurons.

4. Importance of protein structure to its function

The function of a protein is directly related to its structure. Changes in protein structure, whether caused by genetic mutations or environmental factors (such as changes in pH or temperature), can lead to loss of function or an increase in unintended functions. This is why maintaining the proper structure of proteins is critical for them to effectively perform their biological role.

For example, primary structure determines the shape and function of a protein through the specific order of amino acids. Secondary and tertiary structures contribute to the overall shape and stability, ensuring that the protein can properly interact with other molecules. Quaternary structures allow for complex interactions and cooperativity between subunits in multi-subunit proteins.

5. Conclusion

Proteins are indispensable molecules that are critical for the structure, function, and regulation of the body's tissues and organs. Understanding the hierarchical structure of proteins from the elementary to the quaternary levels helps to elucidate their diverse roles in biological systems. Every level of protein structure is critical for the ultimate functionality of the protein. As fundamental building blocks, they underlie the complexity and sophistication of biological machinery.


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Proteins (Structure and Function)

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