Biology 107 Macromolecules I

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Biology 107Macromolecules I
September 2, 2005
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Macromolecules I

• Student Objectives As a result of this lecture
  and the assigned reading, you should understand
  the following
• 1. The four major types of organic macromolecules
  are carbohydrates, lipids, proteins, and nucleic
  acids.
• Carbohydrates generally have molecular formulas
  that are some multiple of CH2O, and carbohydrates
  range from single small sugar molecules
  (monosaccharides) to long polymers of sugar
  monomers (polysaccharides).
• a. Structure - Monosaccharides have two or more
  -OH groups and either an aldehyde or a ketone
  group. Polysaccharides may be straight or
  branched molecules of hundreds or thousands of
  sugar monomers. Some sugars are highly
  negatively charged because they are commonly
  sulfated (SO3-) or because they contain a
  carboxyl group (COO-).

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Macromolecules I

• b. Functions - energy source, recognition or
  signaling, and/or structural.
• Lipids consist mainly of C and H atoms linked by
  nonpolar covalent bonds consequently, lipids are
  not attracted to polar water molecules, and
  lipids are hydrophobic.
• a. Structure
• Fats and oils are large lipids made from
  glycerol and fatty acids. Triglyceride fats
  consist of three (3) fatty acid chains hooked to
  a glycerol molecule. For saturated fats, every C
  atom of the carbon skeleton (except the carboxyl
  carbon) carries 2 H atoms (the maximum number of
  hydrogens). In contrast, unsaturated fats
  contain double bonds and less than the maximum
  number of hydrogens possible.

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Macromolecules I

• Phospholipids, the major components of cellular
  membranes, are structurally similar to fats
  except they contain a phosphate group and only 2
  fatty acid chains attached to the glycerol.
• Steroids are lipids with the carbon chain bent
  to form fused rings. Cholesterol is a common
  substance in animal cell membranes. Animal
  cells also use cholesterol as a precursor for
  making other steroids, including male and female
  sex hormones.
• b. Functions - energy storage, membrane
  structure, hormone signaling, and/or
  insulation.

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Four Main Types of Macromolecules
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Common Carbohydrates Classified by Number of
Carbons
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Examples of Hexose Isomers
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Examples of Linear Compared to Ring Forms of
Carbohydrate
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Disaccharides
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Polysaccharides
Examples Starch Fxn as storage form of
energy Cellulose Fxn as structural material
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Storage Polysaccharides

• Starch and glycogen are storage polysaccarides in
  animals and plants. Polymers of glucose. Reserve
  fuel.
• Starch (plant cells) is an isomer of cellulose
  with a-glycosidic bonds. Unbranched (amylose)
  and branched (amylopectin).
• Glycogen (animal cells) is similar structure to
  starch but with ß-glycosidic bonds and highly
  branched. Degraded from end, so branches allow
  rapid degradation.

Starch
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Glycogen

• Large branched polymer
• Most glucose units linked by ?-1,4 glycosidic
  bonds
• Branches formed by ?-1,6 glycosidic bonds every
  10 glucose units

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Structural Oligosaccharides

• Cellulose - plant cell walls, load bearing. Fifty
  percent of carbon in biosphere. May have up to
  15,000 glucose residues
• Chitin - exoskeletons (crustaceans, insects),
  cell walls of fungi and algae.

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Lipids - Fats
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Triglyceride Fats
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Saturated Fatty Acid Chains
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Unsaturated Fatty Acid Chains
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Comparison of Saturated and Unsaturated Fatty
Acid Chains
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Sources of Saturated and Unsaturated Fatty Acids
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Phospholipids
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Phospholipids in Water
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Structure of Phospholipids and Steroids
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Examples of Lipids Other Than Phospholipids or
Steroids
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Different Types of Macromolecules May be
Covalently Linked (e.g., Glycolipids)