Chapter 5 The Structure And Function Of Macromolecules

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Chapter 5The Structure And Function Of
Macromolecules
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Dehydration Synthesis vs. Hydrolysis
Remove water to link monomers
Add water to break unlink monomers
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Monosaccharides - The Simplest Sugars
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Isomers
C6H12O6
Galactose
Glucose
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Numbering The Carbons

• Carbon atoms are numbered. Carbon-1 contains the
  aldehyde functional group.
• This is a hexose sugar. It contains 6 carbon
  atoms.
• This is a linear form of a sugar molecule.

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Numbering The Carbons

• Carbons are numbered clockwise beginning with 1,
  just to the right of the oxygen atom in the ring
  structure.
• The ring forms are known as pyranose forms
  because they resemble a molecule called a pyran.

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Linear vs. Ring Forms
The predominant forms of glucose and fructose in
solution are ring forms. The aldehyde group on
carbon-1 reacts with the alcohol group on carbon-5
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Linear and Ring Forms
a-D-Glucopyranose
If the OH group on carbon 1 is down (below the
plane of the molecule, its the a form. If its
up, its the ß form. Living things tend to like
the alpha form best.
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Common Dissacharides
Sucrose (Table Sugar Glucose Fructose Lactose
(Milk Sugar) Glucose Galactose Maltose
(Malt Sugar) Glucose Glucose All three have
the chemical formula C12H22O11
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Alpha - Glycosidic Linkages
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Linkages in Polysaccharides
a1-4
ß1-4
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Properties of Polysaccharides

• Composed of many simple sugar monomers
• May be branched or unbranched
• May be food storage or structural parts
• Monomers may be glucose or modified glucose
• Linkages may be alpha or beta forms

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Polysaccharides
Alpha 1-4 or Alpha 1-6 if branched
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Cellulose ß-1-4 Linked Polymer of Glucose
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Chitin A Substituted Sugar
Chitin
Fungi 5-20
Worms 20-38
Squids/Octopus 3-20
Scorpions 30
Spiders 38
Cockroaches 35
Water Beetle 37
Silk Worm 44
Hermit Crab 69
Edible Crab 70
The difference between cellulose molecules and
chitin molecules is that chitin has an amide
group instead of a hydroxyl group (alcohol),
which cellulose has.
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Chitosan Chitosan is a polymer derived from
chitin and is used in applications from health
care to agriculture to dyes for fabrics. There
are even medical applications and companies who
use products made with chitosan as part of weight
loss programs.Chitosan is very similar to
chitin, see below. The difference is that
chitosan has an amine group instead of an amide
group. This just means that chitosan doesn't have
any carbons double bonded to oxygen and chitin
does.
                                                
                Chitosan
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Lipids

• Lipids are used for energy storage
• Lipids are generally hydrophobic
• Can be joined to proteins to make lipoproteins
• Can be joined to sugars to make glycolipids
• May be used for insulation or protection
• Major component of cell membranes

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Triglycerides

• Fats and oils for energy storage
• 3 Fatty acids 1 glycerol molecule joined by an
  ester bond
• 9 cal/gram
• The 3 fatty acids may be different
• Fatty acids vary from approx. 12-18 Carbons in
  length
• Unsaturated fatty acids contain one or more CC
  bonds

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Saturated vs. Unsaturated
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Phospholipid Structure
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Phospholipid Behavior
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Steroids
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Proteins

• Structural Proteins Support
• Storage Proteins Store amino acids
• Transport Proteins Move materials
• Hormonal Proteins Insulin, glucagon
• Receptor Proteins Cell membranes
• Contractile Protein Actin and Myosin
• Defense Protein Antibodies
• Enzymatic Proteins Increase reaction rate

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Amino Acid Structure

• H O
• H N C C OH
• H R
• R - groups are functional groups that may be
  nonpolar hydrocarbons, polar, or charged.
• Functional groups give proteins their unique
  structures and functions.

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Nonpolar R Groups
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Polar and Charged R Groups
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Formation of the Peptide Bond
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Amino Acids

• There are 8 essential amino acids for adults. A
  9th one (Histidine) is essential to infants.
• Since there are 20 amino acids, a chain of 100
  amino acids would have 20100 possible
  combinations of amino acid sequences. Thats a
  lot!!!

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Four Levels Of Protein Structure

• Primary structure The order of the amino acids
  in the protein chain.
• Secondary Structure Alpha helix and Beta
  pleated sheets, resulting from hydrogen bonding
  patterns.
• Tertiary Structure Folding of the entire
  protein due to many interactions.
• Quaternary Structure Several proteins associate
  to form one large structure.

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Primary Structure
Peptide bonds
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Secondary Structure
Beta pleated sheet
Alpha helix
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Tertiary Structure
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Quaternary Structure
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In sickle cell anemia, glutamic acid at position
6 of the beta chains is replaced by the nonpolar
amino acid, valine.
Oxygen affinity is unaffected, but placing the
nonpolar valine on the outside of the molecule
markedly reduces the solubility of the
deoxygenated form of hemoglobin. The result is
sickling when O2 concentrations are low.
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Amino Acid Sequence Matters
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Quaternary Structure of the Enzyme, Ribonuclease
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X-Ray Crystallography
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Summary of the 4 Levels of Structure
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Protein Denaturation
Heat, Acids, Bases, And Salts Can Cause Proteins
To Denature (Change their folding pattern).
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Nucleic Acids
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The Central Dogma Of Biology
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Properties of Nucleic Acids(DNA and RNA)

• Polymers consisting of monomers called
  nucleotides
• Nucleotides are composed of 3 parts Sugar,
  phosphate and one of 4 bases
• Bases may be adenine, guanine, cytosine, thymine
  (DNA only), and uracil (RNA only)
• Sugars Deoxyribose (DNA only) Ribose (RNA
  only)
• Purine bases are (adenine and guanine),
  pyrimidines are (cytosine, thymine, and uracil)
• Negatively charged at physiological pH

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DNA

• Double helical structure
• Sugar-phosphate backbone on the outside
• Bases on the inside hydrogen bonded together
• A purine always pairs with its complementary
  pyrimidine A-T, G-C
• Contains genetic information as a unique sequence
  of bases

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Replication of DNA
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DNA and Evolution

• Genes (DNA) and proteins document the heredity of
  an organism
• Related species have similar DNA and protein
  sequences
• Mutation rates may serve as molecular clocks if
  we know how often they occur