Chapter 9 / 9.4 Proteins

Biomolecules: Proteins and Polysaccharides

🧬 Proteins: Your Body’s Building Crew

Proteins are like chains made of amino acid links! These chains form when peptide bonds connect amino acids together (Figure 9.3).

Key facts about proteins:

• ⭐ Made of 20 types of amino acids (e.g., alanine, lysine, tryptophan).
• ⭐ Since they use multiple amino acid types, proteins are heteropolymers (not homopolymers).
• 🍏 Essential amino acids come from food (our body can’t make them). Non-essential amino acids can be made by our body.
• 💪 Superhero functions:
  • Transport nutrients across cells
  • Fight germs (antibodies)
  • Act as hormones (e.g., insulin)
  • Work as enzymes (e.g., trypsin)
  • Help with senses (receptors for smell/taste)

🌟 Protein Rockstars (Table 9.5)

Fun fact: Collagen is the most common protein in animals, while RuBisCO is the #1 protein in the entire biosphere! 🌍

🍬 Polysaccharides: Nature’s Sugar Chains

These are long chains of sugar units (monosaccharides) found in the acid-insoluble part of cells.

Meet the sugar teams:

• 🌾 Cellulose: Made of only glucose (homopolymer). Forms plant cell walls.
• 🥔 Starch: Plant energy storage! Has helical structures that trap iodine (I₂) → turns blue.
• 🍖 Glycogen: Animal energy storage (branched chain, like Figure 9.2). Has a reducing end (right) and non-reducing end (left).
• 🍐 Inulin: Fructose polymer.

📊 Cell Composition Cheat Sheet (Table 9.4)

💡 NEET Power Topics

1. Protein structure & functions (Heteropolymer, peptide bonds, examples from Table 9.5)
2. Essential vs. non-essential amino acids (Dietary importance)
3. Most abundant proteins (Collagen in animals, RuBisCO globally)
4. Polysaccharide types & tests (Starch-I₂ blue reaction, cellulose/glycogen structure)
5. Cell composition (Water % dominance, macromolecule distribution)

Keep exploring! Every amino acid and sugar chain you learn is a step toward understanding life’s machinery. 🌟 You’ve got this!