Disassembly%20=%20hydrolysis

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Disassembly hydrolysis

• Break bonds between fatty acid glycerol units
• Insert H OH from water

2

• A typical fat molecule has a two-part structure
• glycerol
• fatty acid chains

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Saturated or unsaturated fat?

• In a saturated fat, carbon atoms are surrounded
  by as many hydrogen atoms as possible.
• An unsaturated fat has fewer hydrogen atoms than
  it could have. Monounsaturated presence of one
  double bond, Polyunsaturated more than one
  carbon-carbon double bond. More reactive.

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Types of LipidsTriglycerides
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Types of LipidsPhospholipids

• Phospholipids
• Derived from triglycerides
• Glycerol backbone
• Two fatty acids attached instead of three
• Third fatty acid replaced by phosphate group
• The fatty acids are nonpolar and hydrophobic
• The phosphate group is polar and hydrophilic
• Molecules self arrange when placed in water
• Polar phosphate heads next to water
• Nonpolar fatty acid tails overlap and exclude
  water
• Spontaneously form double layer a sphere

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Phospholipids Form Membranes
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Types of LipidsSteroids

• Steroids
• Cholesterol, Testosterone,
• Oestrogen , Vitamins A,D,E,K
• Skeletons of four fused
• carbon rings
• Figure 2 Cholesterol and three substances made
  from it. The substances have very similar
  molecular structures. (Carbon and hydrogen atoms
  in the molecules have been omitted for clarity.
  The lines represent carboncarbon bonds there
  are carbon atoms at each line junction).

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Proteins

• Amino acids are monomers
• Functions
• Support Collagen, skin
• Enzymes Almost all enzymes are
• proteins
• Transport Hemoglobin
• membrane proteins
• Defense Antibodies
• Hormones Many hormones
• regulate insulin
• Motion Muscle proteins
• Soluble due to Polar NH2 and COOH functional
  groups

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Protein SubunitsThe Amino Acids
Glycine

• Proteins are polymers of amino acids
• Each amino acid has a central carbon atom (the
  alpha carbon) to which are attached
• a hydrogen atom,
• an amino group NH2,
• A carboxylic acid group COOH,
• and one of 20 different types of R (remainder)
  groups OR Z group
• There are 20 different amino acids that make up
  proteins
• All of them have basically the same structure
  except for what occurs at the placeholder Z

General Formula H2N-CHZ-COOH
Alanine
Amino Acid Structural Formula
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Structural Formulas
Z group is drawn in red You will notice each
amino acid has a different Z group (or R group)
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ProteinsThe Polypeptide Backbone

• Amino acids joined together end-to-end
• COOH of one AA covalently bonds to the NH2 of the
  next AA
• Special name for this bond - Peptide Bond
• Two AAs bonded together Dipeptide
• Three AAs bonded together Tripeptide
• Many AAs bonded together Polypeptide
• Characteristics of a protein determined by
  composition and sequence of AAs
• Virtually unlimited number of proteins

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Synthesis and Degradation of a Peptide
Water
peptide linkage
You may want to check out this animation
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Peptide Linkages
A condensation reaction between two amino acids.
Note how the carboxyl and amine groups react in
forming the dipeptide and water.
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Zwitterion
Amino group can act as a base Carboxyl group can
act as acid Bases accept H Acids donate H
Therefore NH2 becomes NH3 ion COOH becomes
COO- ion At a particular pH, the amino acid will
become H3N -CHZ-COO- The pH at which the
structure of the amino acid becomes a zwitterion
depends on the Z (or R group) of the AA
in an acidic solution
in an alkaline solution
in neutral solution
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Protein MoleculesLevels of Structure

• Primary
• Literally, the sequence of amino acids. Controls
  entire shape
• Looks similar to a string of beads (up to 20
  different colors)
• Secondary
• The way the amino acid chain coils, pleats or
  folds
• Parts of the chain attract each other
• Tertiary
• Overall three-dimensional shape of a polypeptide
• Side groups (Z) of amino acids form bonds, may be
  hydrogen bonding, dispersion (intermolecular
  forces) or much stronger ionic or covalent bonds
• Describing what a knot looks like from the
  outside
• Quaternary
• Consists of more than one polypeptide
• Like several completed knots glued together

View an animation of protein folding here
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Levels of Protein Organization
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Protein-Folding Diseases and Protein Markers

• Assembly of AAs into protein extremely complex
• Process overseen by chaperone molecules
• Inhibit incorrect interactions between R groups
  as polypeptide grows
• Defects in these chaperones can corrupt the
  tertiary structure of proteins
• Mad cow disease could be due to mis-folded
  proteins
• On he other hand, correctly constructed proteins
  can be use to identify the onset of disease.
  Proteins utilized in this way are called protein
  markers. An increased level of protein markers
  in a persons blood can also be used to monitor
  disease and test effectiveness of treatment.
  Scientist identify protein markers thorough
  application of IR, NMR and MS spectroscopy.
  Examples of protein markers are enzymes and
  antigens.
• In this emerging area of research, protein
  markers can be used to diagnosis heart attacks
  and some cancer types. There can be alternate
  reasons for elevated levels of protein markers in
  an individual however.
• Refer to p. 197 for further information about the
  specific diagnosis of heart attack and prostate
  cancer through protein markers.

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Enzymes

• Enzymes are biological catalysts
• Properties
• SPECIFICITY
• 1 enzyme ? 1 reaction
• LOWER ACTIVATION
• ENERGY
• increased reaction rate
• CONTROL (regulation)
• Enzymes can be switched on
• or off.

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Enzymes

• Only certain parts of a protein are chemically
  active.
• The tertiary shape of a protein determines which
  active sites are exposed.

• Biological polymers (carbohydrates, lipids,
  proteins, nucleic acids) must be assembled
  precisely!
• Chemical processes must occur in proper sequence.
• Chemical processes require energy (heat) for
  activation.
• Reactions occur very slowly at body temperature.
• Add heat to speed up reaction ? undesirable
  reactions (proteins denature)
• Enzymes speed up reactions by 1010 times, at
  normal body temperatures and pressures and are
  vey selective compared to inorganic catalysts.

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Process of catalysis

• Enzyme attaches temporarily to substrate(s) at
  active site.
• Reaction occurs.
• Product released.
• See p.194 of your textbook for a more detailed
  explanation

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Importance of enzymes

• Enzymatic reactions occur in sequence to make
  natural products.
• Abnormal enzymes can produce abnormal products.

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Sometimes enzymes become no longer functional
Structure of protein very important. Because the
bonds that hold the protein (enzyme) in shape may
be weak hydrogen or even weaker dispersion
forces, altering the conditions can cause the
shape of the molecule to change. This renders the
enzyme as ineffective.
Clumping (Coagulation)
Denaturation is the term used to describe a
change that destroys the biological activity of a
protein.
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Enzyme activity
Figure 12.35Effect of pH on enzyme
activity. Enzymes operate in a small pH range.
Different Enzymes operate at varied optimum
pH levels
Figure 12.34 Effect of temperature on enzyme
activity. Enzymes denature above 40?C