माध्यम चुनें / Select Medium:

झारखण्ड बोर्ड (JAC) • कक्षा XI • Biology • अध्याय 9

अनुमानित समय: 45 Mins

प्रगति: अध्ययनरत

जैव-अणु (Biomolecules)

In Class 11 Biology, "Biomolecules" provides an authoritative, curriculum-verified master resource aligned with the 2026–27 NCERT syllabus.

अध्याय CBT ऑनलाइन टेस्ट दें सभी अध्याय देखें

प्रस्तावना अध्याय अवधारणाएँ अध्याय सारांश स्व-मूल्यांकन अभ्यास टेस्ट दें

⚗️ Have You Ever Wondered?

Why can digestive enzymes in your stomach dissolve a steak into liquid nutrients in three hours at body temperature ($37^\circ\text{C}$), while boiling that same steak with concentrated acid in a chemistry lab takes days? Enzymes are biological catalysts that lower activation energy by a million-fold.

यह अध्याय क्यों महत्वपूर्ण है

In Class 11 Biology, "Biomolecules" provides an authoritative, curriculum-verified master resource aligned with the 2026–27 NCERT syllabus.

अध्ययन से पूर्व (आवश्यक ज्ञान)

Organic compounds from Chemistry.
Carbohydrates, proteins, and lipids from Class 10.
Catalysis.

इस अध्याय के लक्ष्य

Distinguish Micromolecules (amino acids, monosaccharides, nucleotides) and Macromolecules (proteins, nucleic acids, polysaccharides) using Trichloroacetic acid separation.
Analyze Primary, Secondary, Tertiary, and Quaternary protein structure.
Explain Enzyme kinetics: Active site, Substrate binding, Activation energy lowering, and factors affecting enzyme activity (temperature, pH, substrate concentration $V_{\text{max}}$).
Analyze Competitive Inhibition: Malonate inhibiting Succinic Dehydrogenase.
Explain Enzyme Classification (6 classes: Oxidoreductases, Transferases, Hydrolases, Lyases, Isomerases, Ligases) and Co-factors (Prosthetic groups, Co-enzymes, Metal ions).

अध्याय रूपरेखा एवं प्रगति

1 1. Chemical Analysis & Biomolecular...

2 2. Enzyme Mechanics & Michaelis-Men...

3 3. Enzyme Inhibition & Co-factors

सम्पूर्ण सैद्धांतिक एवं वैचारिक अध्ययन

1. Chemical Analysis & Biomolecular Classes

Grinding living tissue with Trichloroacetic acid ($\text{Cl}_3\text{CCOOH}$) yields two fractions:
• Acid-Soluble Pool (Filtrate): Biomicromolecules ($18 - 800\text{ Da}$: amino acids, simple sugars, nucleotides).
• Acid-Insoluble Fraction (Retentate): Biomacromolecules ($>10,000\text{ Da}$: proteins, nucleic acids, polysaccharides).
Lipid Anomaly: Lipids have small molecular weights ($<800\text{ Da}$) but end up in the insoluble retentate because their cell membrane fragments form insoluble vesicles!

2. Enzyme Mechanics & Michaelis-Menten Kinetics

Enzymes are globular proteins with a 3D pocket called the Active Site that binds substrate ($E + S \rightleftharpoons ES \to EP \to E + P$). Enzymes accelerate rates by dramatically lowering the Activation Energy ($E_a$)!
• Factors: Exhibit narrow bell-shaped curves for optimum temperature and pH. Increasing $[S]$ raises velocity until all active sites are saturated at $\mathbf{V_{\text{max}}}$.

3. Enzyme Inhibition & Co-factors

Competitive Inhibition: A chemical inhibitor closely resembling substrate competes for the active site:
• e.g. Malonate resembles succinate and competitively inhibits Succinate Dehydrogenase, arresting bacterial cellular respiration!
Co-factors: Non-protein parts essential for enzyme catalytic activity:
• Prosthetic Group: Tightly bound organic molecule (Haem in peroxidase/catalase).
• Co-enzyme: Loosely bound transient carrier (derived from vitamins: NAD, NADP with Niacin).
• Metal Ions: Form coordination bonds with active site (Zinc in carbonic anhydrase and carboxypeptidase!).

Biomolecules - Key Biological & Anatomical Model

अध्याय का सार संक्षेप एवं 10 मुख्य निष्कर्ष

मुख्य बिंदु 1

Acid-Insoluble Retentate: Macroscopic polymers (>10,000 Da) and membrane lipid vesicles.

मुख्य बिंदु 2

Enzyme Active Site: Specific 3D tertiary cleft docking substrates with geometric complementarity.

मुख्य बिंदु 3

Competitive Inhibition: Molecular mimicry where inhibitor reversibly competes for catalytic active site.

मुख्य बिंदु 4

Prosthetic Groups: Covalently or tightly bonded organic cofactors essential for catalysis.

मुख्य बिंदु 5

Carbonic Anhydrase: Fastest enzyme known, converting $600,000$ $\text{CO}_2$ molecules per second.

स्व-मूल्यांकन अभ्यास (Check Your Understanding)

मूल वैचारिक स्पष्टता की जांच के लिए नैदानिक प्रश्न। पहले स्वयं हल करें, फिर उत्तर देखें।

Lipids have molecular weights not exceeding 800 Da, yet they are found in the acid-insoluble macromolecular fraction during chemical analysis of living tissue. Explain why.

उत्तर एवं व्याख्या देखें

उत्तर: Lipids are small molecular weight compounds, but in cells they are arranged as structural components of cell membranes and organelle membranes. When tissue is homogenized in trichloroacetic acid, cell membranes break into fragments and form spherical water-insoluble vesicles that cannot pass through the filter cloth, ending up in the retentate.
Membrane lipid vesicles are insoluble and trapped in retentate.

Explain how enzymes accelerate the rate of a chemical reaction with a suitable potential energy diagram.

उत्तर एवं व्याख्या देखें

उत्तर: Enzymes accelerate chemical reactions by dramatically lowering the Activation Energy ($E_a$) required to transform substrate molecules into the high-energy unstable Transition State. By lowering this energetic barrier, a far greater fraction of substrate collisions possess sufficient energy to form products.
Lowers the activation energy barrier to reach transition state.

What is Competitive Enzyme Inhibition? Illustrate with the classic example of Succinate Dehydrogenase.

उत्तर एवं व्याख्या देखें

उत्तर: Competitive inhibition occurs when an inhibitor closely resembles the normal substrate in molecular structure and competes directly with the substrate for binding to the enzyme's active site. Example: Inhibition of the enzyme Succinate Dehydrogenase by Malonate, which closely resembles succinate in chemical structure and blocks its oxidation to fumarate.
Inhibitor mimics substrate and blocks active site; e.g. Malonate.

Differentiate between a Co-enzyme and a Prosthetic Group with one example of each.

उत्तर एवं व्याख्या देखें

उत्तर: A Prosthetic Group is an organic compound that is tightly, permanently bound to the apoenzyme protein (e.g. Haem is the prosthetic group in peroxidase and catalase); a Co-enzyme is an organic compound whose association with the apoenzyme is transient and loose, often derived from vitamins (e.g. NAD and NADP containing vitamin Niacin).
Tightly bound (Prosthetic group) vs transiently bound (Co-enzyme).

Describe the four levels of protein structural hierarchy.

उत्तर एवं व्याख्या देखें

उत्तर: (1) Primary structure: linear sequence of amino acids linked by peptide bonds, (2) Secondary structure: local folding into $\alpha$-helix or $\beta$-pleated sheets via hydrogen bonds, (3) Tertiary structure: 3D globular folding stabilized by disulfide, ionic, and hydrophobic bonds (gives active sites), (4) Quaternary structure: spatial assembly of multiple polypeptide subunits (e.g. adult hemoglobin with $2\alpha$ and $2\beta$ chains).
Primary (sequence), Secondary (helix/sheet), Tertiary (3D globe), Quaternary (multi-subunit).

अध्याय का अध्ययन पूर्ण हुआ?

अभ्यास के लिए तैयार?

ऑनलाइन CBT टेस्ट देकर तैयारी का मूल्यांकन करें

झारखण्ड बोर्ड परीक्षा पैटर्न पर आधारित बहुविकल्पीय प्रश्नों का ऑनलाइन टेस्ट दें। तुरंत परिणाम, समय विश्लेषण और प्रत्येक प्रश्न का विस्तृत हल प्राप्त करें।

फाउंडेशन टेस्ट

15 MCQs • मूल अवधारणाएँ

एडवांस्ड टेस्ट

15 MCQs • HOTS और ट्रैप्स