BIOL 203 Lecture Notes - Lecture 7: Saturated Fat, Polyunsaturated Fat, Subcutaneous Tissue
15 Jun 2018
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BIO203
May 16th 2018
Lipids
1. Lipids-an introduction
2. Types of lipids
a. Fatty acids
b. Triglycerides
c. Phospholipids
d. Cholesterol
3. Digestion and absorption of lipids
4. Lipoproteins
5. Cardiovascular disease (CVD)
Lipids are necessary for good health
1. Lipids enhance the flavor and palatability of food.
2. Lipids enhance intestinal absorption of fat-soluble vitamins and phytochemicals
3. Lipids contribute to satiety. Gastric emptying is slowed.
4. Cushion the body e.g. the fatty apron that covers the abdomen -→ called visceral fat
5. Insulate the body → called subcutaneous fat
6. Maintain functional integrity of cells
The cell membrane is made of lipids
7. Lipids are a major source of energy. Lipids are also the only form of energy that is stored for
prolonged periods of time.
-At rest, our cells need energy to carry out their work. Fat is what they use when we are at rest.
-We have an unlimited capacity to store fat
Fats are packed with carbon-hydrogen bonds. It is within these bonds that energy is stored. Fat
has far more C-H bonds per gram than does glucose
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Types of Lipids
1. Fatty acids
2. Triglycerides
3. Phospholipids
4. Cholesterol
Fatty acids
Four things to consider when discussing fatty acids
1. Variation in length & shape
2. Variation in saturation
3. Two are essential fatty acids
4. Trans fats
A fatty acid is a chain of carbon atoms attached to hydrogen atoms.
Fatty acids contain a methyl group (CH3) at one end and an acid group (COOH) (carboxyl group) at the
other.
The carbon atom of the methyl group is considered the end of the molecule. This end is called the
omega end.
Fatty acids differ in the length and shape of the hydrocarbon tail.
The shape of a fatty acid is determined by the number of double bonds.
A fatty acid with no double bonds is said to be saturated. It is saturated with hydrogen atoms –each
carbon atom is paired with 2 hydrogen atoms (with the exception of the 1st and last carbon atoms)
A fatty acid with one or more double bonds is unsaturated.
An unsaturated fatty acid has two neighboring carbon atoms within the chain that are missing hydrogen
atoms. Thus the fatty acid has a double bond.
• Monounsaturated fatty acids: MUFA have one double bonds within the carbon chain
• Polyunsaturated fatty acids: PUFA have two or more double bonds within the carbon chain
Oils are lipids that are liquid at room temperature. They are predominantly composed of unsaturated
fatty acids.
These nearly broken sticks form an unorganized mess of fatty acids preventing the lipids from stacking
tightly.
Consequently, oils are liquid at room temperature
Butter is principally composed of saturated fatty acids.
These stick-straight fatty acids stack neatly and tightly up against one another.
This compact structure is what allows butter to remain solid at room temperature.
Essential fatty acids
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Our cells can synthesize fatty acids using carbohydrates and even protein.
But…. e aot sthesize a fatt aid ith a doule od loated o the rd or th aro ato fro
the methyl end (the omega end).
The names of these fatty acids are omega 3 and 6 fatty acids.
• We eed the.
• We a’t sthesize the.
• The ust e supplied fro the diet.
Omega 3 Fatty acid Family
DHA
• Audat i rai tissue ad essetial for the groth ad functional development of the brain in
infants.
• DHA i the diet iproes learig ailit. A defiie of DHA is assoiated ith defiits i learig
EPA
• Loers lood pressure, redue lood lot foratio, protet agaist irregular hearteats ad reduce
inflammation. In other words, reduce the risk of cardiovascular disease
Trans Fatty Acid (TFA)
Unsaturated fatty acids come in two shapes:
1. If the hydrogen atoms next to a double bond are on the same side of the chain, this is called a cis
configuration.
2. If the hydrogen atoms are on opposite sides, we call it a trans configuration
With the exception of trans fat in butter, all trans fats are manmade.
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Document Summary
Lipids: lipids-an introduction, types of lipids, fatty acids, triglycerides, phospholipids, cholesterol, digestion and absorption of lipids, lipoproteins, cardiovascular disease (cvd) Lipids are necessary for good health: lipids enhance the flavor and palatability of food, lipids enhance intestinal absorption of fat-soluble vitamins and phytochemicals, lipids contribute to satiety. Gastric emptying is slowed: cushion the body e. g. the fatty apron that covers the abdomen - called visceral fat, maintain functional integrity of cells. Insulate the body called subcutaneous fat: lipids are a major source of energy. Lipids are also the only form of energy that is stored for prolonged periods of time. At rest, our cells need energy to carry out their work. Fat is what they use when we are at rest. We have an unlimited capacity to store fat. It is within these bonds that energy is stored. Fat has far more c-h bonds per gram than does glucose. Types of lipids: fatty acids, triglycerides, phospholipids, cholesterol.
