Let’s Explore Chemical Composition in Living Things! 🔬
🧪 Are living things made of different chemicals than non-living things?
When we analyze both living tissues (like plants or liver) and non-living matter (like earth’s crust), we find the same elements – but in different proportions:
| Element | Earth’s Crust (%) | Human Body (%) |
|---|---|---|
| Carbon (C) | 0.03 | 18.5 |
| Oxygen (O) | 46.6 | 65.0 |
| Hydrogen (H) | 0.14 | 0.5 |
| Nitrogen (N) | Very little | 3.3 |
Key takeaway: Living organisms have way more carbon & hydrogen! 🌱
🔎 How to analyze chemical composition?
- Grind tissue in trichloroacetic acid (\( \text{Cl}_3\text{CCOOH} \)) using mortar & pestle
- Strain through cloth → get 2 fractions:
- Acid-soluble pool (thousands of organic compounds!)
- Acid-insoluble fraction
- To find inorganic elements:
- Weigh tissue → get wet weight
- Dry it → get dry weight (water removed)
- Burn it → only ash remains (contains inorganic elements like Ca++, Mg++)
⭐ Meet the Biomolecules!
All carbon compounds from living tissues = biomolecules. They include:
1. Amino Acids (Protein building blocks) 🧱
- Contain amino group (-NH2) & acidic group (-COOH) on same carbon (α-carbon)
- General formula: \( \text{H}_3\text{N}-\text{CH(R)}-\text{COOH} \)
- 20 types in proteins (e.g., glycine, alanine, serine)
- Can be acidic (glutamic acid), basic (lysine), or neutral (valine)
- Special feature: Exist as zwitterions (\( \text{H}_3\text{N}^+-\text{CH(R)}-\text{COO}^- \)) in solution!
2. Lipids (Fats & oils) 💧
- Generally water-insoluble
- Simple types:
- Fatty acids (e.g., palmitic acid: 16 carbons)
- Glycerol (trihydroxy propane)
- Complex types:
- Triglycerides (glycerol + 3 fatty acids)
- Phospholipids (contain phosphorus → found in cell membranes, e.g., lecithin)
3. Nucleotides (Genetic material) 🧬
- Nitrogen bases: Adenine, Guanine, Cytosine, Uracil, Thymine
- Base + Sugar = Nucleoside (e.g., adenosine)
- Nucleoside + Phosphate = Nucleotide (e.g., adenylic acid)
- Nucleotides make DNA/RNA – our genetic material!
📚 High-Yield NEET Concepts
- Elemental comparison: Higher % of carbon & hydrogen in living organisms vs. earth’s crust
- Biomolecule isolation: Acid-soluble pool (organic compounds) vs. acid-insoluble fraction
- Amino acid structure: Zwitterion form (\( \text{H}_3\text{N}^+-\text{CH(R)}-\text{COO}^- \))
- Lipid classification: Triglycerides vs. phospholipids (with phosphorus)
- Nucleotide components: Nitrogen base + sugar (nucleoside) + phosphate (nucleotide)
💡 Fun Summary
Living organisms are carbon-rich factories making amazing molecules! From protein-building amino acids to energy-storing lipids and DNA nucleotides – each has special structures and roles. Remember: More carbon + hydrogen = life! 🌟
