Untitled Flashcard Set

Here are organized notes from your uploaded files covering topics 2–4, elements of life, functional groups, intro to biomolecules, carbohydrates, lipids, and cellulose vs. starch:

Elements of Life

• Life is primarily built from C, H, O, N, P, S.

• Carbon:

  • 4 valence electrons → can form up to 4 covalent bonds.

  • Forms long chains, branching, rings, and double/triple bonds.

• Nitrogen: essential for proteins and nucleic acids.

• Phosphorus: important in nucleic acids and some lipids.

• Hydrogen bonds: intermolecular attractions, crucial for water’s properties.

Functional Groups

• Functional groups are chemical groups attached to carbon skeletons that participate in chemical reactions.

• Examples:

  • Hydroxyl (–OH): alcohols, polar, hydrophilic.

  • Carbonyl (C=O): aldehydes & ketones.

  • Carboxyl (–COOH): acids, polar.

  • Amino (–NH2): bases, found in amino acids.

  • Phosphate (–PO4): highly charged, energy transfer (ATP).

  • Methyl (–CH3): nonpolar, affects gene expression.

Intro to Biomolecules

• Four main classes: Carbohydrates, Lipids, Proteins, Nucleic Acids.

• Polymers = chainlike macromolecules of repeating monomers.

• Formation & breakdown:

  • Dehydration reaction → joins monomers, releases H₂O.

  • Hydrolysis → breaks polymers using H₂O.

Carbohydrates

• Made of C, H, O (formula ~ CnH2nOn).

• Contain carbonyl + multiple hydroxyl groups.

• Monosaccharides: simple sugars (e.g., glucose).

  • Nutrients/fuel for cells (cellular respiration).

  • Building blocks for amino acids, disaccharides, polysaccharides.

• Disaccharides: two monosaccharides joined by glycosidic linkage.

  • Example: sucrose (glucose + fructose), transport sugar in plants.

• Polysaccharides: many sugars joined by dehydration reactions.

  • Storage:

    • Plants: starch (glucose polymer).

    • Animals: glycogen (stored in liver & muscles).

  • Structural:

    • Cellulose: plant cell walls.

    • Chitin: exoskeletons of arthropods.

Lipids

• Not true polymers; all are hydrophobic (nonpolar).

• Types: fats, phospholipids, steroids.

Fats

• Made of glycerol + 3 fatty acids → joined by ester linkages → form triglycerides.

• Saturated fatty acids:

  • No double bonds; straight chains; solid at room temp (butter, lard).

• Unsaturated fatty acids:

  • 1+ double bonds; kinked chains; liquid at room temp (oils).

Phospholipids

• 2 fatty acids + glycerol + phosphate group.

• Assemble into bilayers:

  • Hydrophilic heads outward, hydrophobic tails inward → forms cell membranes.

Steroids

• Four fused carbon rings.

• Functional groups determine type.

• Examples:

  • Cholesterol: stabilizes animal cell membranes.

  • Testosterone & Estrogen: hormones controlling body functions.

Cellulose vs. Starch

• Both are glucose polymers, but differ in glycosidic linkages.

• Starch:

  • α-glucose linkages → helical shape.

  • Easily digested by animals for energy storage.

• Cellulose:

  • β-glucose linkages → straight, rigid structure.

  • Forms plant cell walls.

  • Indigestible for humans; some organisms rely on symbiotic microbes to break it down.

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