Lipids: Not Just Fat BIOL 103, Chapter 6-1
Today’s Topics
• What are Lipids?• Fatty Acids are Key Building Blocks• Triglycerides• Phospholipids• Sterols
Lipids
• Essential nutrients• Provide energy• Help transport fat-soluble nutrients• Contribute to flavor and texture of food
What are Lipids?
• Lipids include…– Triglycerides (__________________________)
• In body: stored in adipose tissue• In food: “fats and oils”
– Phospholipids (_________________________)• Plant and animal origin• Body can make them• Soluble in fat and water
– Sterols (_______________________________)• Most well known: Cholesterol
Fatty Acids are Key Building Blocks
• Fatty Acids – Determine whether a fat is ________________ at
room temperature– Basic structure:
• Chain length– ____________ Carbon length
Fatty Acids are Key Building Blocks
• Saturation– Saturated fatty acids
• _________________________ between carbons
– Unsaturated fatty acids• _______________________________1. Monounsaturated fatty acid (MUFA):
– _______________________
2. Polyunsaturated fatty acid (PUFA):– ________________________
– Fats with more bonds are generally more _____________
Fatty Acids are Key Building Blocks
Cis fatty acids• Occurs ________________• Chain is _______________
Trans fatty acids• Produced by ____________
(adds hydrogen to an unsaturated fatty acids)
• A small portion of trans fat can occur naturally
• Chain is ________________
Trans Fat
• In health, trans fatty acids are known to raise LDL (“bad”) cholesterol, and lower HDL (“good cholesterol”), promote systemic inflammation, and increase triglycerides in your blood.
• History and how it is made:– In Europe (1910): needed a cheaper butter substitute
for soldiers– In US (1960s): People wanted to eat a “healthier and
cheaper butter” food scientists decided to hydrogenate vegetable oil to solidify them
Fatty Acids are Key Building Blocks
• Nonessential and essential fatty acids1. Nonessential fatty acids
• Can be made in the body• Not “essential” to have in your diet
Fatty Acids are Key Building Blocks
• Nonessential and essential fatty acids (cont.)2. Essential fatty acids
• Can’t be made in the body
• Must come from food• _________________________________________________________________• Used to make
eicosanoids
Triglycerides• Structure
– ________________________• Functions
1.Energy source: 9 kcal/g2.Energy reserve: form of stored energy in _________
___________________________________________3. Insulation and protection:
1. Visceral fat ____________________________2. Subcutaneous fat _________________________________
4.Carrier of ____________________________5.Sensory qualities in food
Triglycerides in Food
• Found in a variety of fats and oils• Classified by their most prevalent type
– Saturated fatty acids: _________________ and tropical oils
– Polyunsaturated fatty acids: _________________• Omega-3: soybean, flaxseed oils; salmon, tuna• Omega-6: seeds, nuts, corn oil, meat, poultry, eggs
What are the positive and negative consequences of hydrogenating a fat?
(Problem Set 6, #3)
Pros
1. _____________________ _____________________
2. _____________________ _____________________
Cons
1. ______________________2. ______________________
______________________
• Oxidation causes food to spoil and damage body tissues
Phospholipids
• Structure– _______________________________
• Functions:1.____________________
• Keep fat suspended in water• Keep oil and water mixed
2._____________________ for cell membranes
Phospholipids
• Cell membrane– Double layer of
phospholipids– Store fatty acids
temporarily and release them as needed
– Important role in nerve cells
• e.g. Ach
Phospholipids
• Lipid transport– Stomach
• Breaks fat into tiny particles for digestion
– Intestine• Continues emulsifying fat
– Blood• _____________________________________ that
carry lipid particles to their destinations in the body
Phospholipids
• Emulsifiers (Lecithin)– In body
• Phospholipid with choline ___________________
– In food• Blend of phospholipids
with different nitrogen-containing components
• Used as emulsifiers (e.g. salad dressing, chili, sloppy-joe mixes, and chewing gum).
Phospholipids
• Phospholipids in food– Occur naturally in plants and animals– Examples: Egg yolks, liver, soybeans, peanuts– _________________________ because the body
can make it
Sterols
• A category of lipids that include cholesterol
• Structural characteristics:– ____________________– ____________________