LIPIDS LIPIDS Elements CHOP mostly HYDROPHOBIC MOSTLY hydrocarbons

LIPIDS

LIPIDS Elements: CHOP - mostly HYDROPHOBIC - MOSTLY hydrocarbons NET affect - NON-POLAR Types: fats and oils phospholipids steroids waxes

Function: 1. energy storage – fat and oil 2. Protection and insulation - fat Ex: Blubber 3. structure – phospholipids and cholesterol 4. chemical communication - steroids 5. repel water- waxes

FATS AND OILS Structure - two parts 1. glycerol - three carbon chain with three hydroxyls 2. fatty acid - long chain of hydrocarbons with a carboxyl head �carboxyl head combines with hydroxyl of glycerol by dehydration synthesis so 3 fatty acids combine with the glycerols = triglycerol or triglyceride � The massive amounts of hydrocarbons in the tail make fats NONPOLAR

Fats and Oils Constructed from a glycerol and three fatty acids Result = TRIGLYCERIDE

FATS vs. OILS FATS - animal derived - solid at room temp � OILS - mostly plant derived - liquid at room temp crucial difference? bonding in the fatty acids tails �

- Fats are saturated - Oils are unsaturated both have the same basic structure of glycerol plus three fatty acids - fats: fatty acids are all single bonds making the chains essentially straight - pack together nicely - solid at room temperature - oils: fatty acids are unsaturated due to double bonds - causes the chains to bend in the cis conformation - don’t pack together very nicely – liquid at room temperature

� Saturated fatty acids �Have the maximum number of hydrogen atoms possible �Have no double bonds Stearic acid Figure 5. 12 (a) Saturated fat and fatty acid

� Unsaturated fatty acids �Have one or more double bonds Oleic acid Figure 5. 12 (b) Unsaturated fat and fatty acid cis double bond causes bending

PARTIALLY HYDROGENATED OILS BAD BAD BAD

� Hydrogenated Oils �Unsaturated oils are heated and treated with hydrogen gas and a catalyst to break the double bond add hydrogen ○ - this makes them saturated ○ Heating the oils can also cause isomerization and switch the cis double bond to a trans double bond making it a TRANS fat ○ TRANS fats are not able to be processed by our cells and lead a higher interaction with “bad” cholesterol and can potentially lead to inflammation in the blood vessels exacerbating heart disease

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ENERGY Content of Foods � - fats and oils: 9 Cal/g � - carbs: 4 Cal/g - protein: 4 Cal/g - alcohol: 7 Cal/g � �

PHOSPHOLIPIDS Function: STRUCTURE - cell membranes Composition: Hydrophilic head: - phosphate joined to glycerol = POLAR - joins with other polar molecules Hydrophobic tail: two chains not three

� Phospholipid is amphipathic CH 2 Figure 5. 13 + N(CH ) 3 3 CH 2 O O P O – Choline Phosphate O CH 2 CH O O C CH 2 Glycerol O Hydrophobic tails Hydrophilic head �Both hydrophilic and hydrophobic (a) Structural formula Fatty acids Hydrophilic head Hydrophobic tails (b) Space-filling model (c) Phospholipid symbol

Reaction with water: heads out tails in 1. micelle 2. liposome - cell membrane – PHOSPHOLIPID BILAYER

Phospholipids in Water

• The structure of phospholipids – Results in a bilayer arrangement found in cell membranes WATER Hydrophilic head WATER Hydrophobic tail Figure 5. 14

Steroids four fused rings examples: testosterone estrogen cholesterol - stabilize cell membranes

Estradiol OH CH 3 HO Female lion OH CH 3 O Figure 4. 9 Male lion Testosterone

• Cholesterol – Is found in cell membranes – Is a precursor for some hormones H 3 C CH 3 HO CH 3

Understanding Blood Lipid Panel Total Cholesterol: - Composite of triglyceride levels, LDL, and HDL - Triglycerides: - Normal Levels: 150 mg/d. L - Function: energy – body converts extra energy to triglycerides (fat) and stores it

- LDL: Low Density Lipoproteins - “bad” cholesterol - Function: transport cholesterol throughout the body for absorption by the cells - Normal Levels: Between 100 – 129 mg/d. L - Issues: LDL bind more readily to the glycoproteins on the surface of the blood vessel endothelium (cell on the surface of the wall) and become oxidized forms fatty plaques (atherosclerosis) that can harden (arteriosclerosis) to narrow the diameter of the blood vessels and make them less flexible (increases blood pressure)

- HDL: High Density Lipoproteins - “good” cholesterol - Normal Levels: 40 -50 mg/d. L for men 50 – 60 mg/d. L for women > 60 mg/d. L = lower risk of heart disease - Function: removal of lipids from the blood stream

� Hypercholesterolemia �Genetic condition that causes a lack of LDL receptors on the surface of cells �Result in very high levels of cholesterol in blood

�Animation of LDL receptors �Receptor Mediated Endocytosis ○ Part II

� The deal with Fats � Unconventional But Effective Therapy for Alzheimer's Treatment: Dr. Mary T. Newport at TEDx. USF