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LIPIDSRyan Jeffery, Ali Loperena, Neil Jethani, Dee White, Sammy Soliman, Nicolette Canale, Jon Chernov, Keith Wright
OBJECTIVE B.4.1Ryan 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
Choline GroupGlycerol
Fatty Acid Chain
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.4.2Ali 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.• Both LDL and HDL have the same chemical
structure.
4.2 OUTLINE THE DIFFERENCE BETWEEN HDL AND LDL CHOLESTEROL AND OUTLINE ITS IMPORTANCE.
HDL LDL
Full Name High Density Lipoproteins
Low Density 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.4.3Neil 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 C-C
Straight chains Greater (more atoms) stronger interaction
High (solid at room temp)
Unsaturated One C=C (mono-) or several C=C (poly-)
Double-bonds kinked chain
Lesser (fewer atoms) weaker interaction
Low (liquid at room temp)
OBJECTIVE B.4.4Dee White
Linoleic (omega-6 fatty acid)
Poly-unsaturated fatty acid Carboxylic acid with an 18
carbon chain and two cis double bonds (C=C) cis means on the same
side The first double bond is
located at the sixth carbon from the methyl end (aka- the omega end) and the second is located at the ninth.
Linolenic (omega-3 fatty acid)
Poly-unsaturated fatty acid Carboxylic acid with an 18
carbon chain and three cis double bonds (C=C) cis means on the same
side The first double bond is
located at the third carbon from the methyl end (aka- the omega end), the second is located at the sixth, and the third is located at the ninth.
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.
Carboxylic Acid
Carboxylic Acid
omega end omega end
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.4.5Ms 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.4.6Sammy 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
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)
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
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)
B.4.6 DESCRIBE THE CONDENSATION OF GLYCEROL AND THREE FATTY ACID MOLECULES TO MAKE A TRIGLYCERIDE (2)
Glycerol
Triglyceride
Hydroxyl Group
Ester bond
Fatty Acid Tail
Carboxyl Group
Condensation Reaction
B.4.6 DESCRIBE THE CONDENSATION OF GLYCEROL AND THREE FATTY ACID MOLECULES TO MAKE A TRIGLYCERIDE (2)
OBJECTIVE B.4.7Nicolette 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.4.8Jonathan 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.4.9Keith 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
Chronic Acid Reflux
Osteoarthritis