Exam 1 BIOLOGY lecture 3

Chapter 3: Lipids and Carbohydrates

• 3.1.1 Define lipids based on their insolubility in water.

• 3.1.2 Identify triglycerides and phospholipids from their chemical structure.

• 3.1.3 Recognize the difference between saturated and unsaturated fatty acids and explain how saturation affects how closely they can pack together.

• 3.1.4 List some of functions of lipids.

• 3.2.1 Draw the ring form of five- and six-carbon carbohydrates.

• 3.2.3 Define the difference between mono-, di-, oligo-, and polysaccharides.

• 3.2.4 Describe the functional consequences of linear versus branched polysaccharides, and how branching

occurs in terms of the positional carbons involved in the bonding.

3.1 Lipids Are Characterized by Their Insolubility in Water

  • Macromolecules: lg molecules formed by covalent linkages of smaller molecules

    1. proteins (polymer)

    2. carbohydrates (polymer)

    3. lipids (hydrocarbons)

    4. nucleic acids (polymer)

  • Polymers created by covalent linkage of smaller molecules called monomers. formed and broken apart in reactions involving water.

  • Condensation (forms more complex molec): removal of water creates covalent bond b/w monomers

  • Hydrolysis (forms more simple molec): the addition of water breaks a covalent bond between monomers

  • Lipids:

    • store energy in C-C and H-H bonds. hydrocarbons

    • nonpolar covalent bonds > insoluble in water

    • van der waals interactions

    • structural role in cell membrane

    • fat in animal bodies serves as thermal insulation

  • Triglycerides (simple lipids). little polarity, extremely hydrophobic

    • fats - solid at room temp

    • oils - liquid at room temp

      • 3 fatty acids (-COOH), 1 glycerol (-OH)

    • synthesis of triglyceride involves 3 condensation rxns

  • fatty acid chain varies in length/structure.

    • amphipathic: hydrophilic end, hydrophobic tail

    • Saturated fatty acids: all bonds b/w carbon atoms are single. they are saturated w/ Hs

    • Unsaturated fatty acids: hydrocarbon chains contain 1+ double bonds. they cause kinks and prevent molecule from tightly packing

  • Phospholipid: 2 fatty acids and a phosphate (negative charge, hydrophilic) compound bound to glycerol

    • form a bilayer in aq solutions.

    • bilayer in biological membranes

    • bilayer: hydrophobic tails and phosphate containing head

  • Carbohydrates

    • source of stored energy

    • transport stored energy within complex organisms

    • structural molecules give organisms their shapes

    • recognition or signaling molecules that can trigger specific biological responses

      • lg gp of molecules, similar composition, differ in several important properties.

      • composition: Cn(H2O)n’

    • Simple sugars: small carbohydrates (12 or less carbons)

    • lg carbohydrates = polymers of simple sugars

    • Monosaccharides: 5/6 C, usually in ring

    • Polysaccharide: large poylmers of monosaccharides; chains can branch.

      • starches: family of polysaccharides of glucose

      • glycogen: highly branched polymer of glucose. main energy storage molec in mammals

      • cellulose: MOST ABUNDANT organic biological compound on Earth. good structural material

    • disaccharide - 2 monosaccharides linked by glyosidic bond

    • oligosaccharide: 3-10 monosaccharides joined by glyosidic bonds

      • bonded to proteins and lipids on cell surfaces > serve as recognition signals