Chapter 5 The Structure and Function of Macromolecules

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Chapter 5The Structure and Function of
Macromolecules
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Types of Macromolecules

• Carbohydrates
• Lipids (phospholipids)
• Proteins
• Nucleic Acids

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Polymers

• Covalent monomers
• Condensation reaction (dehydration reaction)
• One monomer provides a hydroxyl group while the
  other provides a hydrogen to form a water
  molecule
• Hydrolysis
• bonds between monomers are broken by adding
  water (digestion)

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Carbohydrates

• Monosaccharides CH2O formula
• multiple hydroxyl (-OH) groups and
• 1 carbonyl (CO) group
• Aldehyde sugar (aldose)
• Ketone sugar (ketose)
• Cellular Respiration
• raw material for amino acids and fatty acids

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Linear and Ring Forms of Glucose
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• Disaccharides
• glycosidic linkage
• (covalent bond) between
• 2 monosaccharides
• covalent bond by dehydration reaction
• Sucrose
• most common
• disaccharide
• glucose fructose

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Polysaccharides of Glucose

• Structural
• Plants cellulose
• Animals chitin

• Storage
• Plants starch (plastids)
• Animals glycogen

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Glycogen branched structure
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Chitin structure
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Lipids

• No polymers glycerol and fatty acid
• Fats, phospholipids, steroids
• Hydrophobic H bonds in water exclude fats
• Carboxyl group fatty acid
• Non-polar C-H bonds in fatty acid tails
• Ester linkage 3 fatty acids to 1 glycerol
  (dehydration formation)
• Triacyglycerol (triglyceride)
• Saturated vs. unsaturated fats
• single vs. double bonds

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Lipids Diverse Hydrophobic Molecules

• Fats - store large amounts of energy, solid or
  oil
• - glycerol 3 fatty acid molecules
• Phospholipids - cell membranes
• - glycerol, 2 fatty acids and PO4 group
• Steroids - precurser to sex steroids, cell
  membranes
• - 4 fused carbon rings with functional
  groups

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LDLs (bad) carry cholesterol from the liver to
the body, leaving deposits in the blood vessels.
HDLs (good) carry cholesterol from the body
back to the liver for elimination
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Manufacturers bombard cis fats with hydrogen
(hydrogenation) in order to render the oil more
solid better shelf life and cooking
characteristics.
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Phospholipids

• 2 fatty acids instead of 3 (phosphate group)
• Tails hydrophobic heads hydrophilic
• Micelle (phospholipid droplet in water)
• Bilayer (double layer)cell membranes

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Structure of a Phospholipid
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Steroids

• Lipids with 4 fused carbon rings
• E.g. cholesterol cell membranes precursor for
  other steroids (sex hormones) atherosclerosis

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Proteins

• Importance
• Instrumental in nearly everything organisms do
  50 dry weight of cells most structurally
  sophisticated molecules known
• Monomer amino acids (there are 20)
• Carboxyl (-COOH) group, amino group (NH2),
  variable group (R)
• Variable group (R) characteristics
• polar (hydrophilic), nonpolar
  (hydrophobic), acidic or basic
• Three-dimensional shape (conformation)
• Polypeptides (dehydration reaction)
• peptide bonds covalent bond carboxyl group to
  amino group (polar)

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Protein Structure
Animation 5.4.1
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Primary Structure

• Conformation Linear structure
• Molecular Biology each type of protein has
  a unique primary structure of amino acids
• Amino acid substitution hemoglobin sickle-cell
  anemia

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Primary Structure of Proteins
Animation 5.4.2
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Secondary Structure

• Conformation coils folds (hydrogen
  bonds)
• Alpha Helix coiling keratin
• Pleated Sheet parallel silk

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Secondary Protein Structure
Animation 5.4.3
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Tertiary Structure

• Conformation irregular contortions from R
  group bonding.
• Hydrophobic and v.d.w.
• disulfide bridges
• hydrogen bonds
• ionic bonds

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Tertiary Protein Structure
Animation 5.4.4
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Quaternary Structure

• Conformation 2 or more polypeptide
  chains aggregated into 1 macromolecule
• e.g. collagen (connective tissue)
• E.g. hemoglobin

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Quaternary Protein Structure
Animation 5.4.5
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Denaturation and Re-naturation of a
Protein
High temperatures or various chemical treatments
will denature a protein, causing it to loose its
conformation and hence its ability to
function. Proteins can often re-nature when the
chemical and physical aspects of its environment
are restored.
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Spider Silk
Normal length, 5 times length,
20 times length
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• Spider silk is 5 times stronger than steel

Spider silk goes through this sort of stretching
before it breaks, and in doing so, it absorbs a
lot of energy. The energy that you're putting
into pushing it or pulling it is actually being
taken up by the stretching process. This
energy-absorbing process is what makes the
material so tough.
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Prions
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Nucleic Acids

• Deoxyribonucleic acid (DNA)
• Ribonucleic acid (RNA)
• DNA-gtRNA-gtprotein
• Polymers of nucleotides (polynucleotide)
• nitrogenous base
• pentose sugar
• phosphate group
• phosphodiester bond
• Nucleoside base sugar
• Nitrogenous bases
• pyrimidinescytosine, thymine, uracil
• purinesadenine, guanine

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Double helix (Watson Crick - 1953)

• Inheritance based
• on DNA replication
• H bonds - between
• paired bases
• van der Waals - between stacked bases
• A to T C to G pairing
• Complementary

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The Double Helix