Objective B.4.6

							LIPIDS
Ryan Jeffery, Ali Loperena, Neil Jethani, Dee
White, Sammy Soliman, Nicolette Canale, Jon
Chernov, Keith Wright
OBJECTIVE B.4.1
Ryan Jeffery
WELCOME BACK!
   It’s very nice to see you all again!
       Now let’s get to work
OBJECTIVE 4.1
   Assessment Statement
       Compare the composition of the three types of lipids
        found in the human body.
   Teacher’s Notes
       Examples include triglycerides (fats and oils),
        phospholipids (lecithin), and steroids (cholesterol).
TRIGLYCERIDES




     Fatty Acid Chains can very in length!
Chains are always EVENLY numbered in length!
COMPOSITION OF A TRIGLYCERIDE
   Triglycerides have two parts
     Glycerol
     Fatty Acids

   Glycerol
     Seen in Green
     3 Carbon atoms bonded to 3 Hydroxyl Groups

   Fatty Acids
     Carboxyl group
     Bonded to a hydrocarbon chain approximately 16 to
      18 carbons long
EXAMPLES
 Fat Molecules and Oils
 Both are found in abundance in fast food

 Both are linked to an increased risk of heart
  disease and stroke.
PHOSPHOLIPIDS




                           Fatty Acid Chain
                Glycerol
Choline Group
PHOSPHOLIPIDS
   Make up most of the plasma membrane
       PHOSPHOLIPID Bi-layer
   First discovered in egg yolk by Theodore Nicolas
    in 1847
LECITHIN
   First phospholipid discovered
       Specifically Phosphatidylcholine
   Composed of:
     Glycerophosphoric Acid (one saturated, one
      unsaturated fatty acid)
     Choline Head

   Found in:
     Animal Tissue
     Plant Tissue
     Egg Yolks
STEROIDS*
STRUCTURE
   20 Carbon Atoms
       Form Four Rings
         Three Cyclohexane rings (C6H12) (A,B,C)
         One Cyclopentane ring (C5H10) (D)

         Yes, that’s more than 20 C – They share


 Varying functional groups
 Varying oxidation states
CHOLESTEROL
OBJECTIVE B.4.2
Ali Loperena
    B.4.2 Outline the difference between HDL and LDL
    cholesterol and outline its importance.




•   Cholesterol has a four ring structure
    characteristic of all steroids.
•    The structure of cholesterol is called the steroid
    backbone
     •   Look for this in the hormones section and in the
         medicines and drugs unit.
•   Cholesterol is transported around the body by
    lipoproteins.
4.2 OUTLINE THE DIFFERENCE BETWEEN HDL
AND LDL CHOLESTEROL AND OUTLINE ITS
IMPORTANCE.

                   HDL                LDL
Full Name          High Density       Low Density
                   Lipoproteins       Lipoproteins
Approximate Size   8-11 nm            18-24 nm
•LDL transports cholesterol to the arteries where it
lines the walls. Atherosclerosis (thickened arteries) can
lead to cardiovascular disease.
    •Major sources of LDL are saturated fats. In
    particular those derived from lauric (C12 ), mystiric
    (C14 ), and palmitic (C16 ).
•HDL can remove cholesterol from the arteries and
transport it back to the liver.
OBJECTIVE B.4.3
Neil Jethani
B.4.3 DESCRIBE THE DIFFERENCE IN
STRUCTURE BETWEEN SATURATED AND
UNSATURATED FATTY ACIDS.

 SATURATED- carboxyl group connected to ONLY
  single bonded C atoms bonded to H atoms. (C-C)
 UNSATURATED- carboxyl group connected to c
  atoms with at least one group of double bonded C
  atoms. (C=C)
       The double bond causes fats (ex. triglyceerides) to have a
        lower melting/boiling point-the double bond tends to keep
        the fat flat-linear----usually oils at room temp
   Steric effect (relevant to shape): the interjection of
    double bonded C atoms prevent the fatty acid
    molecules from approaching each other closely and
    hence interacting via Van der Waals’ forces.
B.4.3 DESCRIBE THE DIFFERENCE IN
STRUCTURE BETWEEN SATURATED AND
UNSATURATED FATTY ACIDS.

 Most naturally occurring fats and oils contain a
  mixture of saturated, mono-unsaturated and
  polyunsaturated fatty acids and are classified
  according to the predominant type in the
  mixture.
 Examples:
       Unsaturated: Linseed soil (flax plant) has a low
        percentage of saturated fatty acid.
           Vegetable lipids are usually unsaturated
       Saturated: Beef tallow (from beef fat) has a high
        percentage of saturated fatty acids.
           Animal lipids tend to be saturated
B.4.3 DESCRIBE THE DIFFERENCE IN
STRUCTURE BETWEEN SATURATED AND
UNSATURATED FATTY ACIDS.

     SATURATED         UNSATURATED
  B.4.3 DESCRIBE THE DIFFERENCE IN
  STRUCTURE BETWEEN SATURATED AND
  UNSATURATED FATTY ACIDS.

                        Summative Table


Type          Molec. Structure Phys. Structure     Van der Waals      Melting Points


Saturated     All single bonds   Straight chains   Greater (more     High (solid at
              C-C                                  atoms)  stronger room temp)
                                                   interaction

Unsaturated   One C=C (mono-) Double-bonds         Lesser (fewer      Low (liquid at
              or several C=C   kinked chain       atoms)  weaker    room temp)
              (poly-)                              interaction
OBJECTIVE B.4.4
Dee White
B.4.4 COMPARE THE STRUCTURES OF THE TWO
ESSENTIAL FATTY ACIDS LINOLEIC (OMEGA–6
FATTY ACID) AND LINOLENIC (OMEGA–3 FATTY
ACID) AND STATE THEIR IMPORTANCE.


Linoleic (omega-6 fatty acid) Linolenic (omega-3 fatty acid)
 Poly-unsaturated fatty acid    Poly-unsaturated fatty acid
 Carboxylic acid with an 18     Carboxylic acid with an 18
  carbon chain and two cis        carbon chain and three cis
  double bonds (C=C)
                                  double bonds (C=C)
    cis means on the same
                                    cis means on the same side
      side
 The first double bond is       The first double bond is located

  located at the sixth carbon     at the third carbon from the
  from the methyl end (aka- the   methyl end (aka- the omega
  omega end) and the second is    end), the second is located at the
  located at the ninth.           sixth, and the third is located at
                                  the ninth.
                              omega end
omega end

            Carboxylic Acid
                                          Carboxylic Acid
Why so important?
   Linoleic (omega-3 fatty acid) and Linolenic (omega-6 fatty acid)
    are ESSENTIAL for human health.
   We must have them in our diets because our metabolism cannot
    synthesize them from food components.
   A lack of omega-6 fatty acids causes dry hair, hair loss, and poor
    wound healing.
   Omega-3 fatty acids are thought to decrease the chances of
    cardiovascular diseases and prostate cancer.
   Both of these fatty acids are thought to help lower LDL
    cholesterol.
   Linoleic and linolenic are found in vegetable oils such as
    sunflower oil, poppy seed oil, corn oil, and canola oil; as well as in
    soybeans, hemp, and walnuts.
OBJECTIVE B.4.5
Ms M
B.4.5 DEFINE THE TERM IODINE NUMBER
AND CALCULATE THE NUMBER OF C=C
DOUBLE BONDS IN AN UNSATURATED
FAT/OIL USING ADDITION REACTIONS.
OBJECTIVE B.4.6
Sammy Soliman
B.4.6 DESCRIBE THE CONDENSATION OF
GLYCEROL AND THREE FATTY ACID
MOLECULES TO MAKE A TRIGLYCERIDE (2)

   Glycerol:
       3-carbon backbone
       carbon 1 and 3 have two hydrogen and one hydroxyl
        group attached
       carbon 2 has one hydrogen and one hydroxyl group
        attached
       all bonds are covalent
       the hydroxyl groups are polar allowing for dipole-dipole
        interactions
   Fatty Acid:
       long carbon chain backbone
       all bonds are covalent and non-polar
B.4.6 DESCRIBE THE CONDENSATION OF
GLYCEROL AND THREE FATTY ACID
MOLECULES TO MAKE A TRIGLYCERIDE (2)

   Fatty Acid (continued):
       two types:
         Saturated – all single bonds (no more hydrogen atoms can
          be accepted)
         Unsaturated – at least one or more double bonds between

          carbon atoms (can accept at least or more hydrogen atoms
          making it saturated)
       Carbon 1 has a single bond with a hydroxyl group and a
        double bond with an oxygen (carboxyl group)
       Middle carbons have 2 hydrogen attached in saturated
        fats and can vary between two, one, or no hydrogen
        attached in unsaturated fats depending on the
        placement of double bonds
       End carbons have three hydrogen attached
B.4.6 DESCRIBE THE CONDENSATION OF
GLYCEROL AND THREE FATTY ACID MOLECULES
TO MAKE A TRIGLYCERIDE (2)

   Triglyceride:
       Composed of three fatty acids attached to one glycerol
        molecule via three separate ester bonds
       Formed by a condensation reaction
   Condensation Reaction:
       Requires three fatty acids and one glycerol
       The three fatty acids are bonded to the glycerol molecule
        through a process known as esterification
       The hydroxyl groups of the glycerol and the hydrogen in
        the hydroxyl groups of the acids are lost during the
        process
       Each oxygen from the hydroxyl groups of the fatty acids
        are then bonded to a separate carbon of the glycerol by
        an ester bond forming a triglyceride
B.4.6 DESCRIBE THE CONDENSATION OF
GLYCEROL AND THREE FATTY ACID MOLECULES
TO MAKE A TRIGLYCERIDE (2)

   Condensation Reaction (continued):
       The three hydroxyl groups and the three hydrogen
        atoms that were lost form three water molecules (the
        reason the reaction is called a condensation reaction)
B.4.6 DESCRIBE THE CONDENSATION OF
GLYCEROL AND THREE FATTY ACID
MOLECULES TO MAKE A TRIGLYCERIDE (2)

                      Hydroxyl
                      Group

                      Fatty
                      Acid Tail




  Glycerol
                                             Carboxyl Group
             Ester bond




                              Triglyceride
B.4.6 DESCRIBE THE CONDENSATION OF
GLYCEROL AND THREE FATTY ACID
MOLECULES TO MAKE A TRIGLYCERIDE (2)

   Condensation Reaction
OBJECTIVE B.4.7
Nicolette Canale
B.4.7 DESCRIBE THE ENZYME-CATALYSED
HYDROLYSIS OF TRIGLYCERIDES DURING
DIGESTION

  Essentially the reverse of B.4.6
  During digestion
  Triglycerides broken down (hydrolyzed) by enzymes
   (lipases)  glycerol and fatty acids
  In turn these are broken down by a series of redox
   reactions  carbon dioxide, water, and energy
B.4.7
OBJECTIVE B.4.8
Jonathan Chernov
B.4.8 EXPLAIN THE HIGHER ENERGY VALUE
OF FATS AS COMPARED TO CARBOHYDRATES
(3)

   Fats: Long hydrocarbon chains; most of the mass
    in a fatty acid or triglyceride is from carbon, and
    a small percentage is from oxygen
       Ex: C18H38O6
   Carbohydrates: Contain equal proportions of
    carbon and oxygen and twice as much hydrogen
    atoms
       Ex: C6H12O6 (fructose)
   When fats and carbohydrates are metabolized,
    the main products are CO2 and H2O
       The carbon and hydrogen form strong bonds with
        oxygen which result in the large release of energy
B.4.8 EXPLAIN THE HIGHER ENERGY VALUE
OF FATS AS COMPARED TO CARBOHYDRATES
   Reason: Amount of oxidation that takes place as the
    compounds are converted to CO2 and H2O
     Fats require more oxidation to be converted than
      carbohydrates
     Carbohydrates have one oxygen atom for every carbon
      atom, so each carbon atom needs only one more oxygen and
      each pair of hydrogen atoms need one more oxygen
           Carbohydrates make fewer C-O bonds because the bonds
            already exist
       In fats most carbons are bonded to hydrogen atoms, so
        when fats are metabolized they form more new C-O bonds,
        releasing more energy than carbohydrates
           Each carbon atom needs two oxygen atoms instead of one,
            while each hydrogen needs one oxygen
       The bond enthalpy of the C-O bond is high, so when it
        forms a large amount of energy is released
   Fat molecules require about half as much oxygen for
    the same number of carbon atoms
       Oxidation of fats is longer, but produces more energy
B.4.8 EXPLAIN THE HIGHER ENERGY
VALUE OF FATS AS COMPARED TO
CARBOHYDRATES

   When comparing fats and carbohydrates gram to
    gram:
     More oxygen is included in the weight of a
      carbohydrate
     Fats have more carbon atoms per gram when
      weighed, which means they will release about twice
      as much energy as carbohydrates
 Fats: 9 kilocalories/gram
 Carbohydrates: 4 kilocalories/gram
B.4.8 EXPLAIN THE HIGHER ENERGY
VALUE OF FATS AS COMPARED TO
CARBOHYDRATES

   Examples of metabolization reactions:
     Fat: O2 + C58H112O6  CO2 + H2O + energy
     Carbohydrate: C6H12O6 + 6 O2  6 CO2 + 6 H2O +
      energy
OBJECTIVE B.4.9
Keith Wright
OBJECTIVE B.4.9

Describe the important
 roles of lipids in the
 human body and the
 negative effects that can
 have on health.
MEMBRANES
 Lipids compose the selectively-permeable
  membranes required for diffusion.
 Phospholipids consist of a polar, hydrophilic
  phosphate ‘head’ and two hydrophobic fatty acid
  ‘tails’.
MEMBRANES
   The fact that one end of the phospholipid will
    always point toward water and one will always
    point away creates the structure of the
    phospholipid bilayer.
ENERGY STORAGE
•   Triglyceride lipids are used to store energy.
•   Because the three hydrocarbon chains of a
    triglyceride are hydrophobic, they remain stable
    in the presence of less water.
•   Thus, lipids require only one-sixth the amount of
    water to be activated that glycogen does.
•   When fully metabolised, one triglyceride yields
    NADH, FADH2 and Acetyl CoA, which are used
    in Cellular Respiration to produce 14 ATP.
STEROIDS
 Steroid Hormones are cholesterol-based
  molecules that are used in cell-signalling.
 Steroids consist of the cyclohexane rings and one
  cyclopentane ring, to which various functional
  groups are attatched.
STEROIDS
 Steroids act by binding to surface proteins on the
  cell membrane, or in the cytoplasm. The
  hormone-protein complex enters the nucleus and
  binds to a specific gene sequence, increasing or
  decreasing the frequency of transcription.
 Video:
  http://www.youtube.com/watch?v=oOj04WsU9ko
INSULATION
 Lipids are natural insulators.
 Lipids are covalent compounds that do not
  conduct heat or electricity easily.
 Lipid-filled cells called adipocytes found in the
  subcutaneous layer of skin for an insular barrier
  to help maintain body temperature.
HEALTH EFFECTS
Ω-3 FATTY ACIDS

 Ω-3s are unsaturated hydrocarbon chains that
  have a carbon double-bond from the third Carbon
  down.
 Certain Ω-3s reduce the risk of heart disease by
  increasing circulation and breaking down the
  fibrin protein responsible for bloodclots.
 This clears the blood vessels and lightens the
  heart’s workload, thus decreasing the risk of
  heart attack and heart disease.
CHOLESTEROL & LDLS

 Cholesterol is a steroid that is important for
  biomolecular synthesis and membrane fluidity.
 LDL is a small lipoprotein containing cholesterol.
 A high-cholesterol diet can result in a high
  concentration of LDLs in the bloodstream.
 These LDLs accumulate on the walls of arteries,
  where they harden and obstruct bloodflow.
CHOLESTEROL & LDL
OBESITY
 Obesity is the excess accumulation of body fat.
 Energy-rich carbohydrates and lipids from the
  diet that are not metabolised are stored as lipids
  in the adipocytes.
 Increased need for lipid storage leads to the
  growth of more adipose tissue, increasing body
  mass.
OBESITY
 This increased body mass and weight puts strain
  on the heart, joints, and skeleton, resulting in
  increased risk of heart disease, arthritis, and
  thrombosis.
 Increased lipid concentration hampers the
  functioning of the liver, kidneys, and brain.
FATTY LIVER DISEASE
OTHER DISEASES




Gallstones


                                       Osteoarthritis
                 Chronic Acid Reflux