Biologically Important Molecules Flashcards

Biologically Important Molecules

Carbohydrates

  • Monosaccharides: Basic unit, (CH<em>2O)</em>n(CH<em>2O)</em>n where n = 3 (trioses), 5 (pentoses), or 6 (hexoses). Isomers have the same chemical formula, but different structure.
  • Disaccharides: Formed by a dehydration/condensation reaction (releasing water) creating a glycosidic bond, that requires energy.
  • Polysaccharides: Condensation polymerization forms large molecules. Properties depend on length, branching, folding, and whether the chain is straight or coiled.

Lipids

  • Triacylglycerol: Formed from glycerol + 3 fatty acids via condensation reaction.
  • Saturated Fats: Maximum number of hydrogens; no double bonds.
  • Unsaturated Fats: Contain carbon-carbon double bond(s).
    • Monounsaturated: one double bond.
    • Polyunsaturated: multiple double bonds.
    • Cis-unsaturated fats: hydrogens on the same side of the double bond, creates a kink, liquids at room temperature.
    • Trans-unsaturated fats: hydrogens on opposite sides, manufactured, more likely to be solid at room temperature, linked to cardiovascular diseases.
  • Cholesterol: Amphipathic lipid; component of cell membranes, precursor to steroids and vitamin D. Transported by HDL ('good') and LDL ('bad').
  • Phospholipids: Amphipathic with a hydrophilic head and hydrophobic tail; form bilayers.

Proteins

  • Built from amino acids (amine + carboxyl + R group).
  • Amino acids can be hydrophobic, hydrophilic, acidic, or basic based on R groups.
  • Primary Structure: Linear sequence of amino acids.
  • Secondary Structure: Local segments (alpha helices, beta sheets).
  • Tertiary Structure: 3D shape, determined by side chain interactions.
  • Quaternary Structure: Arrangement of multiple protein subunits.
  • Cofactors Non-protein molecule required by an enzyme for catalytic activity.

Functional Groups

  • Key groups include aldehydes, amides, amino, carbonyl, carboxylic acid, esters, and others (methyl, ether, guanidinium, imidazole, phenyl, acetyl, sulfhydryl, disulfide, carbonyl (aldehyde), anhydride, carbonyl (ketone), amino (protonated), thioester, phosphoryl, carboxylate, amido, phosphoanhydride, hydroxyl (alcohol), imine, enol, N-substituted imine (Schiff base), and Mixed anhydride (carboxylic acid and phosphoric acid))