Polymer Principles

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Polymer Principles

• Most macromolecules are polymers.
• Polymer large molecule consisting of many
  identical or similar subunits connected together.
• Monomer subunit or building block molecule of a
  polymer.
• Macromolecule large organic polymer
• Formation of macromolecules from smaller building
  block molecules represents another level in the
  hierarchy of biological organization.
• Four classes
• Carbohydrates, Lipids, Proteins, Nucleic Acids

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Polymer Principles cont

• Dehydration reaction or Condensation reaction
  polymerization reactions during which monomers
  are covalently linked, producing net removal of a
  water molecule for each covalent linkage.
• Process requires energy.
• Process requires biological catalysts or enzymes.

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Polymer Principles cont

• Hydrolysis a reaction process that breaks
  covalent bonds between monomers by the addition
  of water molecules.
• Example Digestive enzymes catalyze hydrolytic
  rxns which break apart large food molecules into
  monomers that can be absorbed into the
  bloodstream.

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Polymer Principles cont

• Question
• Monomers are linked into polymers by ______
• _______, which involve the _________ of a
  water molecule.
• - Polymers are broken down to monomers by _______
  ________, which involves the _______ of a water
  molecule.

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An immense variety of polymers can be built from
a small set of monomers.

• Structural variation of macromolecules is the
  basis for the enormous diversity of life.
• There is unity in life as there are only about 40
  to 50 common monomers used to construct
  macromolecules.
• There is diversity in life as new properties
  emerge when these universal monomers are arranged
  in different ways.

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Carbohydrates Fuel and Building Materials

• Sugars, the smallest carbohydrates, serve as fuel
  and carbon sources
• Carbohydrates organic molecules made of sugars
  and their polymers
• Monomers are simple sugars called
  monosaccharides.
• Polymers are formed by condensation rxns.
• Classified by the number of simple sugars.

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Monosaccharides

• Simple sugar in which C, H, and O, occur in the
  ratio of (CH2O).
• Are major nutrients for cells.
• Glucose is the most common.
• Can be produced by photosynthesic organisms from
  CO2, H2O, and sunlight.
• Store energy in their chemical bonds which is
  harvested by cellular respiration.
• Their carbon skeletons are raw materials for
  other organic molecules.
• Can be incorporated as monomers into
  disaccharides and polysaccharides.

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Characteristics of a Sugar

• An OH grp is attached to each carbon except one,
  which contains a carbonyl grp.
• Size of the carbon skeleton varies from three to
  seven carbon. Most common are

Classification No. of Carbons Example
Triose 3 Glyceraldehyde
Pentose 5 Ribose
Hexose 6 Glucose
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Disaccharides

• A double sugar that consists of two
  monosaccharides joined by a glycosidic linkage.
• Glycosidic linkage covalent bond formed by a
  condensation rxn between two sugar monomers.
• Example maltose

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Disaccharides

• Examples of disaccharides

Disaccharides Monomers General Comments
Maltose Glucose Glucose Important in brewing beer
Lactose Glucose Galactose Present in Milk
Sucrose Glucose Fructose Table sugar most prevalent transport form in plants
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Polysaccharides

• The polymers of sugars, have storage and
  structural.
• Polymers of a few hundred or thousand
  monosaccharides.
• Are formed by linking monomers in enzyme-mediated
  condensation rxns.
• Two important biological functions
• Energy storage (starch and glycogen)
• Structural support (cellulose and chitin)

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Storage polysaccharide

• Starch glucose polymer that is a storage
  polysaccharide in plants.
• Helical glucose polymer with a ? 1-4 linkage
• Stored as granules within plant organelles called
  plastids
• Amylose, the simplest form, is an unbranched
  polymer
• Amylopectin is branched polymer
• Most animals have digestive enzymes to hydrolyze
  starch
• Major sources in the human diet are potatoes and
  grains (e.g. wheat, corn, and friuts)

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Storage polysaccharide

• Glycogen glucose polymer that is a storage
  polysaccharide in animals.
• Large glucose polymer that is more highly
  branched (? 1-4 and 1-4 linkages) than
  amylopectin.
• Stored in the muscle and liver of humans and
  other vertebrates.

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Structural polysaccharides

• Cellulose linear unbranched polymer of
  D-glucose in ? 1-4, ? 1-4 linkages
• Major structural component of plant cell walls.
• Differs from starch in its glycosidic linkages

Starch Cellulose
Glucose monomers ? configuration ? 1-4 linkage Glucose monomer ? configuration ? 1-4 linkages
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Structural polysaccharides

• Chitin
• Structural polysaccharide that is a polymer of an
  amino sugar
• Forms exoskeletons of arthropods
• Found as a building material in the walls of some
  fungi
• Monomer is an amino sugar, similar to
  beta-glucose with a nitrogen-containing group
  replacing the hydroxyl on carbon 2

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Lipids

• Insoluble in water
• Include fats, oils, and waxes
• Many have three fatty acids attached to a
  glycerol molecule. (Triglyceride)
• Fatty acids
• Saturated
• Unsaturated
• Monounsaturated and polyunsaturated

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Lipids

• Phospholipids
• Similar to triglycerides except that one of the
  fatty acid chains is replaced by a phosphate
  group.
• Phosphate and glycerol are polar.
• Structural foundation of cell membranes.
• Steroids
• Backbone of four linked carbon rings
• Includes cholesterol and hormones, including
  testosterone and estrogen.

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Proteins

• Central to almost every life function.
• A protein is a functional molecule that consists
  of one or more polypeptides, each folded into a
  specific 3D-shape.
• Polypeptide is a polymer of amino acids.
• Monomer Amino acid
• Review page 53 for the 20 amino acids of proteins

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Overview of Protein Functionreview page 52

• Enzymatic proteins
• Storage proteins
• Hormonal proteins
• Contractile and motor proteins
• Defensive proteins
• Transport proteins
• Receptor proteins
• Structural proteins

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Four Levels of Protein Structure(review pages
56-57)

• Primary structure
• The number and order (sequence) of amino acids.
• Dehydration reaction
• Covalent bonding
• Coded by DNA

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Four Levels of Protein Structure CONT

• secondary structure
• Contributes to the proteins overall
  conformation.
• Stabilized by hydrogen bonds between the oxygen (
  with a partial negative charge) of one peptide
  bond and the partially positive hydrogen attached
  to the nitrogen of another peptide bond.

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Four Levels of Protein Structure CONT

• secondary structure
• Alpha helix
• Is a coil produced by hydrogen bonding between
  every fourth peptide bond (3.6 amino acids per
  turn)
• Beta pleated sheets
• Sheets of parallel chains folded into accordion
  pleats
• Regions are held together by either intrachain or
  inter chain hydrogen bonds (between adjacent
  polypeptide.
• Make up the dense core of many globular proteins
  (e.g. lysozyme) and the major portion of some
  fibrous proteins (e.g. fibroin, the structural
  protein of silk).

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Four Levels of Protein Structure CONT

• Tertiary structure
• Three-demensional shape of a protein
• Types of bonds contributing to tertiary structure
• Weak interactions
• Shape is stabilized by the cumulative effect of
  weak interactions.
• Hydrogen bonding between polar side chains.
• Ionic bonds between charged side chains
• Hydrophobic interactions between nonpolar side
  chains in proteins interior

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Four Levels of Protein Structure CONT

• Tertiary structure
• Strong interactions
• Covalent linkage
• Disulfide bridges form between two cysteine
  monomers brought together by folding of the
  protein.

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Four Levels of Protein Structure CONT

• Quaternary structure
• Structure that results from the interactions
  between and among 2 or more polypeptides chains
• Example
• Collagen a fibrous protein with three helical
  polypeptides supercoiled into a triple helix
• Hemoglobin globular protein that has four
  subunits.

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Mutation Change in the primary
structure(review page 58)

• Sickle-Cell Disease
• Inherited disorder
• A change in one amino acid affects the structure
  of the hemoglobin molecule
• Causing red blood cells to deform into a sickle
  shape that clogs tiny vessels.

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Denaturing Proteins

• The bonds and interactions that maintain the
  three-dimensional shape of proteins may be
  disrupted by
• pH
• Salt concentration
• Temperature
• Causing the protein to unravel.

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Nucleic Acids

• Informational polymers
• Nucleic acids store and transmit heredity
  information
• Two types of nucleic acids
• DNA- deoxyribonucleic acid
• RNA- ribonucleic acid
• Flow of information
• DNA ? RNA ? protein

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Nucleic Acids

• A nucleic acid strand is a polymer of nucleotides
• Monomer nucleotide
• Three parts
• Nitrogenous base
• Pyrimidines ? cytosine, thymine, and uracil
• Purines ? adenine and guanine
• Pentose sugar
• Phosphate group