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Chapter 5
The Structures and Functions
of Macromolecules
Polymer Principles
Most Macromolecules are polymers
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Polymer – large molecule consisting of
identical subunits
Monomer – one subunit or a polymer
Macromolecule – large organic polymer
the four classes of macromolecules are
carbohydrates, lipids, proteins, and
nucleic acids
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Polymerization Reactions – reactions
that link monomers together
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Condensation Reactions – monomers are
covalently linked producing a net removal of
a water molecule for each linkage
Hydrolysis – breaks covalent bonds by
monomers by the addition of water
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Digestion
Carbohydrates
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Sugars are the smallest
carbohydrates that serve as fuel
and carbon sources
• Carbohydrates – organic molecules
made of sugars and their polymers
• Monosaccharides – monomers of
simple sugars
• Polymers are formed by condensation
synthesis
Monosaccharide
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Monosaccharides – simple sugar with
C,H,O occurring in the ratio of (CH2O)
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Most common is glucose
Stores energy in chemical bonds
Can be used as monomers in
di/polysaccharides
Structure
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Every carbon has an (-OH) group bonded to
it except one that has a (=O) in form of an
aldehyde or ketone
Carbon skeleton my have numbers from 3-7,
may be branched, ringed, or straight
Disaccharides
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Disaccharide – double sugar consisting
of two monosaccharides joined by a
glycosidic linkage
• Glycosidic Linkage – covalent bond formed
due to condensation syn. of two monomers
Disaccharride
Maltose
Lactose
Sucrose
Monomers
Glucose + Glucose
Glucose + Galactose
Glucose + Fructose
General Comments
- Beer production
- Present in milk
- Table sugar
Polysaccharides
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Polysaccharides – few hundred
thousand monosaccharides
responsible for storage and
structural roles in organisms
• Formed by condensation synthesis
• Energy storage (starch and glycogen)
• Structural support (cellulose and
chitin)
Storage Polysaccharides
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Starch – storage polysaccharide in
plants
• Stored as granules in plants called
plastids
• Potato tubers and grains contain most
starch
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Glycogen – storage polysaccharide
in animals
• Stored in muscle and liver
Structural Polysaccharides
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Cellulose – major component of
cell walls
• Reinforces cell walls by forming
parallel molecules called microfibrils
• Chitin – forms exoskeletons of
arthropods, and building material in
fungi.
Lipids
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Compounds that are insoluble in
water but will dissolve in nonpolar
solvents (kerosene,benzene,ethenol)
Important groups are fats, oils,
waxes and phospholipids
• Fats – store long term energy
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Composed of one glycerol molecule
Composed of three fatty acids
• Nonpolar hydrocarbon chain
Glycerol Molecule
This side of the
molecule makes bonds
with fatty acids.
Fatty acids
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-composed of a carboxyl group at
one end and an attached
hydrocarbon with a skeleton of 16-18
C’s.
-nonpolar C-H bonds make the chain
hydrophobic and not water soluble.
Fatty acid
Saturated Fatty acid
Unsaturated Fatty acid
-no double bond in
fatty acid tail
-carbon skeleton of
fatty acid is bonded to
a maximum number
of hydrogen atoms
-most animal fats
-solids at room temp.
-one or more double
bond sin fatty acid tail
-tails kink at C=C
bonds not allowing it
to pack closely
together
-most vegetable and
fruits fats
-liquids at room temp.
Fatty Acid
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Useful functions
• One gram of fat stores twice as much
energy as one gram of carbohydrate
• Cushions and insulates vital organs
Phospholipids
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Compounds with molecular building
blocks of glycerol, two fatty acids,
and a phosphate group attached to
another polar molecule
Hydrocarbon tails are hydrophobic
while phosphate heads are
hydrophilic (cell membranes)
Phospholipds
Ester Linkage
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Bond produced from the
condensation synthesis due to
enzyme activity between the
(OH) group on the glycerol and the
carboxyl group on the fatty acid.
Triglyceride-three fatty acids
bonded by ester linkages to one
glycerol.
Tryglyceride Formation
Proteins
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polypeptide chains-polymers of
amino acids that are linked by
peptide bonds
protein-macromolecule that consists
of one or more polypeptide chains
folded and coiled into specific
conformations
• Makes up 50% of body’s dry weight,
structural support, chemical signaling,
enzymes......
Proteins
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Polypeptide chain- polymer of
connected amino acids.
• amino acid- building block of a protein;
most consist of an asymmetric carbon
(alpha carbon),hydrogen atom, carboxyl
group, amino group, and an R group
Amino acid Structure
Peptide Bonds
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peptide bond- covalent bond formed
by a condensation rxn. That links the
carboxyl group of one aa to an amino
group of another aa
Levels of Protein Structure
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Primary structure- unique sequence
of amino acids.
• determined by genes
• Sanger sequenced insulin by acid
hydrolysis and chromatography
separation in the 1940's
Levels of Protein Structure
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Secondary structure-folding of the
polypeptide backbone.
• alpha helix-helical coil that is stabilized
by hydrogen bonding-(3.6 aa per turn)
• Pauling and Corey 1951
• beta pleated sheet-sheet of antiparallel
chains folded into accordion pleats
Levels of Protein Structure
Levels of Protein Structure
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Tertiary Structure- three dimensional
shape due to side chain bonding (R
groups).
• Weak interactions due to H bonding
between polar side chains, ionic bonds
between charged side chains,
hydrophobic bonds between non polar
side chains of the proteins' interior
• Covalent linkage due to disulfide bridges
Levels of Protein Structure
Levels of Protein Structure
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Quaternary structure-interactions
between many polypeptide chains
Denaturation
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Denaturation- process that alters'
protein conformation and biological
activity.
• organic solvents disrupt hydrophobic
side chains
• chemical agents that disrupt H bonds
• excessive heat
Nucleic Acids
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Deoxyribonucleic Acid
• double stranded
• contains instructions for cell activity and
its own replication
• makes up genes; primarily found in
nucleus
Nucleic Acids
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Ribonucleic Acid
• single stranded
• involved in protein synthesis
-messenger RNA carries genetic code in
form of aa to ribosomes.
• flow of genetic information travels from
• DNA-RNA-Cytoplasm
Nucleic Acids
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Phosphate group- attached to
number 5 carbon
Nitrogen base
• Pyrimidine-six member ring
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cytosine/thymine/uracil
• Purine-five member ring
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guanine/adenine
Nucleic Acids
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Phosphodiester linkages-bond between the phosphate of
one nucleotide and the sugar of another (sugar backbone of
DNA)
Inheritance is based on the replication of the double helix.
(Watson and Crick)
• two chains wound around a double helix with sugar backbones on the
outside
• two strands are held together by H bonding between nitrogenous
bases
• base pairing is as follows: A-T/G-C
• both strands are complimentary
Nucleic Acids
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Nucleic acid strand is a polymer of
nucleotides
• nucleic acid-polymer of nucleotides
linked by condensation rxn.
• nucleotide-building block of nucleic acid;
made of a five-carbon sugar bonded to
a phosphate group and a nitrogenous
base
Nucleic Acids
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Pentose (5-carbon sugar)
• ribose or deoxyribose