Biopolymers
World D — Polymers & Biomolecules
41.A — THE MACROMOLECULES OF LIFE
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R41.01 What are Biopolymers?
- Large macromolecules produced by living organisms.
- Formed by covalently linking small biological monomers.
- Includes Carbohydrates, Proteins, and Nucleic Acids.
- Fundamentally biodegradable and essential for life.
R41.02 Carbohydrates
- Monomer: Monosaccharides (Simple Sugars).
- Polymer: Polysaccharides (Starch, Cellulose).
- Provide energy storage and structural support.
R41.03 Proteins
- Monomer: Amino Acids.
- Polymer: Polypeptides.
- Perform almost all cellular work (enzymes, structure, transport).
R41.04 Nucleic Acids
- Monomer: Nucleotides.
- Polymer: DNA and RNA.
- Store and transmit genetic information.
41.B — CARBOHYDRATES (SUGARS & STRUCTURE)
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R41.05 Sugars to Polysaccharides
- Glucose ($C_6H_{12}O_6$) is a monosaccharide ring.
- Rings link via Glycosidic bonds (releasing water).
- Long chains form complex carbohydrates (Polysaccharides).
R41.06 Starch & Glycogen
- Energy Storage.
- Starch (Plants): Amylose (coiled/helical) and Amylopectin (branched).
- Glycogen (Animals): Highly branched, stored in liver and muscles for quick energy release.
R41.07 Cellulose
- Structural Support. Forms plant cell walls.
- Straight, unbranched chains of glucose.
- Chains stack tightly and form strong Hydrogen bonds.
- Humans cannot digest it (dietary fiber).
41.C — PROTEINS (THE WORKHORSES)
R41.08 Amino Acids
- The building blocks of proteins. 20 standard types.
- Central Carbon attached to an Amino group ($-NH_2$), a Carboxyl group ($-COOH$), and an R-group.
- The R-group (side chain) determines the unique properties.
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R41.09 Protein Folding Levels
- Primary: Sequence of amino acids (Peptide bonds).
- Secondary: Alpha-helices and Beta-sheets (Hydrogen bonds).
- Tertiary: Overall 3D shape (R-group interactions, disulfide bridges). Function depends on this shape.
R41.10 Enzymes
- Proteins that act as biological catalysts.
- They speed up reactions without being consumed.
- Lock and Key model: The enzyme's 'active site' specifically fits one particular 'substrate'.
41.D — NUCLEIC ACIDS (THE CODE)
R41.11 Nucleotides
- The monomers of DNA and RNA.
- Made of 3 parts: A Phosphate group, a 5-Carbon Sugar (Ribose/Deoxyribose), and a Nitrogenous Base.
- Link to form a sugar-phosphate backbone.
Adenine
Thymine
Guanine
Cytosine
R41.12 DNA & Base Pairing
- Deoxyribonucleic Acid. Double-stranded helix.
- Stores genetic instructions.
- Complementary Base Pairing: A pairs with T (2 H-bonds), G pairs with C (3 H-bonds).
R41.13 RNA & Transcription
- Ribonucleic Acid. Usually single-stranded.
- Contains Uracil (U) instead of Thymine (T).
- Acts as the messenger (mRNA) that reads the DNA code and takes it to the ribosome to build proteins.