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 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 _______________________________ Monounsaturated fatty acid (MUFA): _______________________ Polyunsaturated fatty acid (PUFA): ________________________ Fats with more bonds are generally more _____________

Fatty Acids are Key Building Blocks Cis fatty acids Trans fatty acids Occurs ________________ Chain is _______________ 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 acids 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.) Essential fatty acids Can’t be made in the body Must come from food ___________________ _______________________ Used to make eicosanoids

Triglycerides Structure Functions ________________________ Energy source: 9 kcal/g Energy reserve: form of stored energy in _________ ___________________________________________ Insulation and protection: Visceral fat ____________________________ Subcutaneous fat _________________________________ Carrier of ____________________________ Sensory qualities in food

Apple vs. Pear

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 What are the positive and negative consequences of hydrogenating a fat? (Problem Set 6, #3) Oxidation causes food to spoil and damage body tissues Pros Cons _____________________ _____________________ ______________________ ______________________ ______________________

Phospholipids Structure Functions: _______________________________ Keep fat suspended in water Keep oil and water mixed _____________________ for cell membranes Our bodies can make phospholipids, so we do not to eat them in our diet Both hydrophobic and hydrophilic Tails: Hydrophilic Head: Hydrophobic Makes it possibly to communicate with the watery environments of blood and cell fluids, yet with a lipid portion that allows other lipids to nter and exit cells.

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 Intestine Blood 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 In food 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: ____________________

Sterols Cholesterol functions: ________________________of cell membranes Precursor to other substances Examples: __________________________________, Manufacture bile salts Cholesterol synthesis in _________________ Sterols in food Found only in _____________________