Biomolecules: Comprehensive NEET Chemistry Formulae Summary

1. Carbohydrates

1.1 General Formula of Carbohydrates

• General Formula: ${\text{C}}_x({\text{H}}_2\text{O}{)}_y$
• • Explanation: Most carbohydrates fit the general formula ${\text{C}}_x({\text{H}}_2\text{O}{)}_y$, indicating they are hydrates of carbon. For example, glucose has the formula $\text{C}6\text{H}12{\text{O}}_6$.
  • Units: None (molecular formula).

Common Misconception:

Not all compounds that fit this formula are carbohydrates. For instance, acetic acid (${\text{C}}_2{\text{H}}_4{\text{O}}_2$) fits but is not a carbohydrate.

1.2 Hydrolysis Reactions

1. Sucrose Hydrolysis: $\text{C}12\text{H}22{\text{O}}_{11}+{\text{H}}_2\text{O}\to \text{C}6\text{H}12{\text{O}}_6+\text{C}6\text{H}12{\text{O}}_6$
2. • Explanation: Sucrose, when hydrolyzed, yields glucose and fructose, both of which are monosaccharides.
   • Conditions: Hydrolysis is typically performed in the presence of dilute acids or specific enzymes.
2. Starch Hydrolysis: $(\text{C}6\text{H}10{\text{O}}_5{)}_n+{\text{nH}}_2\text{O}\to \text{nC}6\text{H}12{\text{O}}_6$
3. • Explanation: Starch or cellulose, upon hydrolysis, yields glucose molecules.
   • Conditions: Hydrolysis of starch requires boiling with dilute ${\text{H}}_2{\text{SO}}_4$ under pressure at 393 K.

Did You Know?

Glucose is the most abundant organic compound on Earth and is crucial for energy in living organisms.

2. Proteins

2.1 Formation of Peptide Bonds

• Peptide Bond Formation: ${\text{R}}_1\text{COOH}+{\text{R}}_2{\text{NH}}_2\to {\text{R}}_1\text{CONH}{\text{R}}_2+{\text{H}}_2\text{O}$
• • Explanation: A peptide bond is formed between the carboxyl group of one amino acid and the amino group of another, releasing a molecule of water.
  • Units: None (reaction process).

Common Misconception:

Students often forget that the peptide bond is an amide linkage, not just a simple covalent bond between carbon and nitrogen.

2.2 Classification of Amino Acids

• Amino Acids: General structure: ${\text{R-CH(NH}}_2\text{)-COOH}$
• • Explanation: The structure of amino acids is composed of an amino group (${\text{-NH}}_2$), a carboxyl group ($\text{-COOH}$), and a side chain (R group), which varies for each amino acid.

3. Nucleic Acids

3.1 Formation of Nucleotides

• Nucleotide Structure: $\text{Nucleoside + Phosphate}\to \text{Nucleotide}$
• • Explanation: A nucleotide is formed when a nucleoside (base + sugar) attaches to a phosphate group. For example, ATP (Adenosine triphosphate) is a nucleotide.
  • Units: None (molecular structure).

NEET Problem-Solving Strategy:

Always ensure you understand the difference between a nucleoside and a nucleotide, especially when dealing with DNA and RNA structures.

4. Thermodynamics in Biomolecules

4.1 Standard Gibbs Free Energy Change (ΔG°)

• Formula: $\Delta G°=\Delta H°-T\Delta S°$
• • Explanation: The Gibbs free energy change relates the enthalpy change ($\Delta H°$), entropy change ($\Delta S°$), and temperature (T) of a reaction, predicting whether a process is spontaneous.
  • Units: Typically in Joules (J) or Kilojoules (kJ) for energy.

Real-life Application:

The concept of Gibbs free energy is crucial in understanding metabolic reactions within cells, determining whether a process such as ATP hydrolysis will occur spontaneously.

Quick Recap

• Carbohydrates follow the general formula ${\text{C}}_x({\text{H}}_2\text{O}{)}_y$.
• Proteins are polymers of amino acids linked by peptide bonds.
• Nucleotides are the building blocks of nucleic acids, formed by a nucleoside plus a phosphate group.
• Gibbs free energy ($\Delta G°$) helps predict the spontaneity of biochemical reactions.

Practice Questions

1. Calculate the amount of glucose produced from the hydrolysis of 50 g of starch.
2. Explain the significance of peptide bonds in protein structure.
3. Derive the relationship between $\Delta G°$ and the equilibrium constant (K).
4. Given a DNA sequence, identify the complementary RNA sequence.

Answers:

1. [Detailed calculation steps]
2. [Explanation of peptide bonds]
3. [Derivation steps]
4. [RNA sequence]

This structured summary should help NEET aspirants quickly review the key concepts and formulae related to biomolecules, ensuring they can effectively apply these in their exam preparation.