SWBAT: 1. Describe a lipid2. Describe the

classes of lipids

Chapter 15Lipids

What are lipids?Group of molecules not

defined by structure but by common characteristicsThey are:

• non-polar• soluble in non-polar solvents like

methylene chloride, gasoline, ether• not soluble in polar solvent like water• fats, oils, fatty acids, waxes, steroids,

cholesterol, fat soluble vitamins

Lipids and HealthBMI: Body Mass Index:

Body Fat vs ObesityBlood Lipids

CAD:Coronary Artery Disease

Lipid deposits clogging arteries in the body and heartRisk Factors for CAD

• Hypertension, Diabetes, elevated cholesterol

• smoking• sedentary lifestyle• stress• obesity• male sex• family history• older age

Types of LipidsSaponifiable Lipids:• Prostaglandins• Waxes• Tricylglycerols• Glycerophospholipids

Non-Saponifiable Lipids:• Cholesterol• Steroid hormones

Can be Hydrolyzed

Can NOT be Hydrolyzed

HomeworkChapter 15.1Pg 497#15.2 – 15.4 (even)

SWBAT: 1. Write structures of

fatty acids2. ID saturated and

unsaturated fatty acids

Chapter 15Fatty Acids

Fatty AcidsContains a long carbon

chain attached to a carboxylic acid on C1

Typically contain and even number of carbon atoms – between 10 and 20

Dodecanoic Acid

Lauric Acid

Fatty AcidsThey are:• Aliphatic molecules –

they are both hydrophobic and hydrophilic

• But…overall they are hydrophobic

Hydrophilic

Hydrophobic Cell

Membrane

Fatty Acids to know…

Laura, My Palm Stinks!

Lauric Acid (C12)

Myristic Acid (C14)

Palmitic Acid (C16)

Stearic Acid (C18)

Types of Fatty AcidsSaturated Fatty Acids:• Only single bonds between

the carbon atoms

Monounsaturated Fatty Acids:• Have one double bond in

the carbon chain

Polyunsaturated Fatty Acids:• Have two or more double

bonds

Unsaturated Fatty Acids

trans double bonds

cis double bonds

Shapes of Unsaturated Fatty Acids

Fatty Acids:Physical Properties

Saturated and trans Fatty Acids:

• High melting points (solids) • Perfect alignment – high

Van de Waals intermolecular attractions• Trans fatty acids do

not naturally exist – they are a man made product and are the most stable fatty acids

Fatty Acids:Physical Properties

Unsaturated cis Fatty Acids:

• Lower melting point (liquid at room temp)

• Do not have perfect alignment due to kinks in chain – low Van de Waals

• Less stable – double bonds can break

Both are:C18H36O2

SaturatedMP of 69° Unsaturat

edMP of 13°

ProstaglandinsThey are:• Small polyunsaturated

Fatty Acids that act like hormones mediating a range of symptoms from inflammation to blood pressure

• Synthesized from Arachidonic Acid (AA)

Prostaglandins• Most have a hydroxyl

group on C11 and C15 and a trans double bond at C13• PGE - those with a ketone on C9

• PGF - those with a hydroxyl group on C9

Inflammation is a…• Natural response to

infection and injury• Disease like rheumatoid

arthritis (inflammation of the joints)

Why do we care?

Non Steroidal Anti-Inflammatory Drugs

(NSAIDs)Drug class that includes:• Aspirin• Ibuprofen• Naproxen (Alveve)• Ketoprofen (actron)• Nabumetone (Relafen)Long term use can result

in liver, kidney and gastrointestinal damage

NSAID effect and side effect

Stomach side effect

Video Links

HomeworkChapter 15.2Pg 503#15.6 – 15.18 (even)

SWBAT: 1. Write structural

formula of wax, fat or oil

2. ID the reaction of a fatty acid and an alcohol or glycerol

Chapter 15Waxes, Fats and Oils

Waxes• Found in many plants and

animals (leaves, stems, skin, fur and feathers)

• Is an ester of a saturated Fatty Acid and a long-chain alcohol (14-30 carbon atoms)

Fats and Oils: Triacylglycerols

• The body stores Fatty Acids as fats and oils

• Also called tryglycerides

• Produced by esterification of glycerol and Fatty Acid groups

Fats and Oils: Triacylglycerols

Most fats and oils are mixed triacylglycerolds with two or three different Fatty Acids

from stearic acidfrom palmitic

acidfrom myristic

acidcan be saturated or

unsaturated

Writing Structures for Triacylglycerol

• Each Fatty Acid is attached by an ester bond to one of the hydroxyl groups in glycerol

Alcohol Part:• In

triglycerides always glycerol

Carboxylic Acid Part:• Three Fatty Acids

Fats and Oils:Physical Properties

• A fat is a solid at room temperature (fats in meat, butter, cheese)

• There are exceptions

• Typically from an animal source

• Oil is usually liquid at room temperature (oils – olive, peanut, sunflower)

• Typically from a plant source

Fats and Oils:Physical Properties

• Saturated Fatty Acids have higher melting points because they pack together tightly

• Animal fats usually contain more saturated Fatty Acids than vegetable oils

Melting Points

HomeworkChapter 15.3Pg 507-508#15.20 – 15.28 (even)

SWBAT: Draw the structure of

the product from a reaction of triacylglycerol with hydrogen, or an acid or base

Chapter 15Chem Props of Triacylglycerols

Hydrogenation• Hydrogenation of

unsaturated fats converts carbon-carbon double bonds to single bonds

• Hydrogen gas is heated through oil with a nickel catalyst• Partial hydrogenation changes oil to a soft, semisolid fat (crisco)

H2

Why?• Chemical process

patented in the 1940’s • used to convert oil

surpluses from soybean farming

• into spreadable fats (margarines) to alleviate butter shortage

Problem…Incomplete hydrogenation

leads to the formation of trans-double bonds→ Trans Fats

Trans Fats raise LDL (bad cholesterol ) levels in the body

Consumption of Trans Fats is correlated with a rise in CAD during 1960-2000

FDA prohibits use of Trans Fats & requires labeling

trans fats in our foodVideo Link

Hydrolysis• Breaking the ester bond –

yielding fatty acid & glycerol• First step in the digesting of

triglycerides in the body• Carried out by the enzyme

lipase • Glycerol is soluble in water

• Fatty Acids are not

H+

lipase

Saponification (sapon = soap)• Reacting triglycerides with

a strong base• Yields glycerol and Fatty

Acid Salts (soap)

Glycerol tritearate + 3 NaOH glycerol + 3 sodium stearate

What is Soap• Soaps are aliphaic

molecules that have a polar part (facing water molecules) and a non-polar part (facing greasy dirt)

• Ancient soap making – Animal fats are heated with a strong base (lye from burnt limestone)

• Fatty acid salts – Sodium paltmitate: Na+ -OOC-(CH2)14-CH3

• Soap Making Video

Food Labels

Food Labels

Olestra• Fatty Acids from

cottonseed or soybean oils

• Composed of 6 to 8 long-chain Fatty Acids attached to sucrose rather than glycerol• We can’t digest it so “Fake Fat” goes straight through our system

• GI problems occurred

HomeworkChapter 15.4Pg 512-513#15.30 – 15.36 (even)

SWBAT: 1. Describe the

characteristics of glycerophospholipids

Chapter 1515.5 Glycerophospholipids

What are Glycerophospholipids?• Similar to triglycerides

except one hydroxyl group is replaced by the ester of phosphoric acid and an amino alcohol• Bonded through a phosphodiester bond

GlycerophospholipidsTriglycerides

Amino Alcohols• Three amino

alcohols found in glycerophospholipids are:

choline ethanolamine serine

Lecithins• Lecithins contain choline• Fatty Acids can be same,

different, saturated, unsaturated or mixture

• Abundant in:• brain tissue• nerve tissue• egg yolks • wheat germ

• yeast

Cephalins• Cephalins contain

ethanolamine and sometimes serine

• Abundant in:• brain tissue• nerve tissue• egg yolks • wheat germ

• yeast

Polar?

• Contain both polar and nonpolar regions

• Ionized alcohol and phosphate portion is called “the head”– Can hydrogen bond with water

• Two Fatty Acids represent “the tail”

• Hydrophobic Tails

• Hydrophilic Head Group

Polar and Nonpolar Regions

• Most abundant in lipids in cell membrane

Nonpolar Tails

Polar Head

HomeworkChapter 15.5Pg 515#15.38 – 15.42

SWBAT: Describe the

structure of steroids

Chapter 15Cholesterol & Steroid

Hoemones

General Structure

Steroidnucleus: • Three cyclohexane rings

A,B,C• One cyclopentane ring D

Types of Steroids• Cholesterol• Lipoproteins• Steroid Hormones• Anabolic Steroids

• Why does it have the ending –ol?

Cholesterol

Most abundant steroid in the body

Facts about Cholesterol

• its part of every cell membrane

• insulates nerve and brain tissue

• forms bile for digestion• forms Vitamin D in skin• starting material for steroid hormones:

sex hormones, cortisone• leads to heart attacks

Lipid Metabolism • Cholesterol is so

important that the body does not rely on what you eat….

• It manufactures 80% of the cholesterol needed• Serum Cholesterol Levels in your body can be measured via blood tests: Lipid Panels

Lipid PanelsWhat health care

professional look for…• Total Cholesterol• HDL: High density Cholesterol –

“good”• LDL: Low density Cholesterol –

“bad”

Why?Lowering Cholesterol Levels

is a business….Food industry:

fat free/cholesterol free itemslean meatslow fat dairyhunt against saturated fats

Pharmaceutical industry: statin drugsHMG-CoA reductase inhibitors

LIPITORThe most widely used drug

in the world…• Pharmaceutical drug

lowering cholesterol levels

• Reaps 26 billion in sales per year worldwide

• Side effects range from diabetes, to cancer

Cholesterol LevelsCholesterol levels show

individual variations due to:

• Genetics• Age • General health: cholesterol is an anti-

inflammatory, anti-stress substance, it can rise due to reasons ranging from stress, lack of sleep, drugs and chronic diseases (diabetes)

• Diet: Plant based diets are correlated with lower cholesterol levels

Cholesterol in Food• Egg 250 mg• Crab/Shrimp 150

mg• Beef 85 mg• White chicken 75 mg• Fish 40 mg

• All animal based food contain cholesterol

• All plant based foods contain no cholesterol

Cholesterol and CAD

• Artheriosclerosis is the main cause of CAD

• It is caused by plaque that clog arteries

• Plaque are cholesterol depositsQ: What makes cholesterol form plaque?A: Inflammation

Transporting Fats in Blood

• Lipids are insoluble in the blood (=water)

• Lipids are transported from spherical vesicles called Lipoproteins

• Skin: Phospholipids, Proteins

• Inside: Cholesterol, Triglycerides

Steroid HormonesSex Hormones• Estrogen: development

of female sex characteristics• Testosterone: development of male sex characteristics including muscle anabolism

• Progesterone: prepares uterus for fertilized egg

Steroid HormonesCorticosteroids• Steroid Hormones

produced by the adrenal glands• Natural – Cortisone

• Drug – Prednisone• Helps with:

• stress response• immune response• regulation of

inflammation

Anabolic Steroids• Synthetic

Testosterone derivatives

• Promote muscle growth, reduce body fat

• Short term side effects: broken bones, ruptured tendons, kidney pain

• Long term use lead to kidney, heart, liver damage

• Legal steroid Tren

HomeworkChapter 15.6Pg 522#15.44 – 15.54 (even)

SWBAT: 1. Describe the

composition and function of the lipid bilayer in cell membranes

Chapter 1515.7 Cell Membranes

Cell Membrane• Composed of phospholipid

bilayer• Polar head & nonpolar tails• Semipermeable – items can

enter and leave

Lipid Bilayer• Double row arrangement

of phospholipids

• Hydrophilic polar heads align on outer edges of membrane

• Hydrophobic nonpolar tails move to center

Fluid Mosaic Model• Lipid bilayer contains

unsaturated Fatty Acid• Cis double bonds

causes a non-rigid structure

• In liquid like bilayer:• Proteins• Carbohydrat

es• Cholesterol

HomeworkChapter 15.7Pg 524 – 525 #15.56 – 15.62