Chapter 15 Lipids

Steroids

, also lipids, do not contain fatty acids and cannot be hydrolyzed. They are characterized by the steroid nucleus of four fused carbon rings.

Nonsteroidal anti-inflammatory drugs (NSAIDs)

, such as aspirin, block the production of prostaglandins.

Lipids are characterized by their structures.

1. Lipids such as waxes, fats, oils, and phospholipids are esters that can be hydrolyzed to give fatty acids and other molecules. 2. Steroids, also lipids, do not contain fatty acids and cannot be hydrolyzed. They are characterized by the steroid nucleus of four fused carbon rings.

In atherosclerosis and heart disease,

1. cholesterol forms plaques that adhere to the walls of the blood vessels 2. blood pressure rises as blood has to squeeze through a smaller opening in the blood vessel 3. more plaque forms; there is also a possibility of blood clots blocking the blood vessels and causing a heart attack

Unsaturated fatty acids can be

1. cis, with bulky groups on the same side of C=C 2. trans, with bulky groups on opposite sides of C=C

Identify each of the following as a fatty acid, a triacylglycerol, an amino alcohol, or a glycerophospholipid.

A. glyceryl trioleate → triacylglycerol B. cephalin → glycerophospholipid C. choline→ amino alcohol D. palmitic acid→ fatty acid

are choline, erine, and ethanolamine are ionized at physiological pH of 7.4

Amino alcohols found in glycerophospolipids

True

Animal fats have more saturated fats.

high in calories.

Animals that hibernate eat large quantities of plants, seeds, and nuts that are

hibernation and the body temperature drops to nearly freezing, reducing cellular activity, respiration, and heart rate.

As the external temperature drops, the animal goes into

essential fatty acids.

Because these polyunsaturated fatty acids must be obtained from the diet, they are known as

triacylglycerols is its only source of energy.

During hibernation, the animal's stored fat in the form of

linolenic, eicosapentaenoic, and docosahexaenoic acids.

Examples of omega-3 acids include

monounsaturated,

Fatty acids can be --- with only one double C C bond in the carbon chain.

polyunsaturated,

Fatty acids can be ----with at least two double C C bonds in the carbon chain.

lipids

Glycerophospholipids are the most abundant ---- in cell membranes and play an important role in cellular permeability

nonpolar hydrocarbon tail

Glycerophospholipids have a ------ portion soluble only in nonpolar substances such as lipids

polar head

Glycerophospholipids have a----containing the ionized amino alcohol and phosphate portion, which is strongly attracted to water

polar and nonpolar substances

Glycerophospholipids have both polar and nonpolar regions that allow them to interact with

phosphoester bond

Glycerophospholipids a hydroxyl group that forms an ester with phosphoric acid, which forms another -----with an amino alcohol

ester bonds

Glycerophospholipids contain two fatty acids that form --- with the first and second hydroxyl groups of glycerol

True

Hydrogenation of oils converts some cis double bonds to trans double bonds.

contains the ionized amino alcohol and phosphate,

In a glycerophospholipid, a polar "head"

nonpolar "tails."

In a glycerophospholipid, the hydrocarbon chains of two fatty acids make up the

carbon atoms.

In a skeletal formula of a fatty acid, the ends and bends of the line are the

amide bond to a fatty acid

In a sphingomyelin, the amine group of sphingosine forms an

triacylglycerols

In the body, fatty acids are stored as ---(triglycerides),

lower the tendency of blood platelets to stick together

Omega-3 fatty acids ---, reducing the possibility of blood clots.

phospholipases that hydrolyze phospholipids in red blood cells.

Poisonous snake venom contains

glyceryl tristearate.

The name of the fatty acid formed with three stearic acids becomes

glycerophospholipids and sphingomyelin.

The phospholipids are a family of lipids similar in structure to triacylglycerols; they include

True

There are more unsaturated fats in vegetable oils.

stearic, oleic, and palmetic acids.

Triacylglycerol may contain different fatty acids, such as the triacylglycerol made from

energy storage for animals.

Triacylglycerols are the major form of

three hydroxyl groups of glycerol react with the carboxyl groups of three fatty acids

Triacylglycerols formed when

glycerol to glyceryl

Triacylglycerols named by changing ---and naming the fatty acids as carboxylates

cis and trans isomers.

Unsaturated fatty acids can be drawn as

False

Vegetable oils have higher melting points than fats.

omega-6 acids,

Vegetables contain ---meaning the first double bond occurs at carbon 6 counting from the methyl end of the carbon chain. Examples of omega-6 acids are linoleic and arachidonic acids.

glyceryltristearate

What products are obtained from the complete hydrogenation of glyceryl trioleate?

arachidonic acid is converted to prostaglandins

When tissues are injured, ---that produce inflammation and pain in the area.

C. soluble in water Lipids are nonpolar and therefore are NOT soluble in water.

Which of the following is NOT a characteristic of lipids? A. may contain a carboxylic acid group B. may contain a four-ring structure C. soluble in water D. mostly nonpolar

Humans

are capable of synthesizing some fatty acids from carbohydrates or other fatty acids cannot synthesize sufficient amounts of polyunsaturated fatty acids such as linoleic acid, linolenic acid, and arachidonic acid

Glycerophospholipids

contain two fatty acids that form ester bonds with the first and second hydroxyl groups of glycerol a hydroxyl group that forms an ester with phosphoric acid, which forms another phosphoester bond with an amino alcohol

Saturated fatty acids

contain only single C — C bonds and fit close together in a regular pattern have strong dispersion forces between long carbon chains have higher melting points and are usually solids at room temperature

steroid

contains a fused four-membered ring system

fatty acids

contains long carbon chains

Sphingomyelin

contains sphingosine instead of glycerol contains a fatty acid, phosphate, and an amino alcohol

Foods that contain trans fatty acids from the hydrogenation process include

deep-fried foods bread, baked goods, and cookies crackers and chips stick and soft margarines vegetable shortening

During hydrogenation,

double bonds are converted to C — C single bonds a small number of the cis double bonds are converted to more stable trans double bonds, causing a change in the overall structure of the fatty acids

In hydrogenation reactions,

double bonds in unsaturated fatty acids react with hydrogen gas to produce carbon-carbon single bonds hydrogen gas is bubbled through the heated oil, typically in the presence of a nickel catalyst

Triacylglycerols

esters of glycerol (a trihydroxy alcohol) and fatty acids

Waxes

esters of saturated fatty acids and long-chain alcohols, each containing from 14 to 30 carbon atoms coatings that prevent loss of water by leaves of plants

Fish

has high levels of omega-3 acids, meaning the first double bond occurs at carbon 3, counting from the methyl end of the chain

Saturated fatty acids

have higher melting points than unsaturated fatty acids because they pack together more tightly

Vegetable oils

have low melting points because they have a higher percentage of unsaturated fatty acids than do animal fats.

fatty acids

includes carbonyl groups

Oleic acid

is a monounsaturated fatty acid found in olives, with one double bond at carbon 9.

Oleic acid

is a monounsaturated fatty acid.It is a liquid at room temperature. The long carbon chain makes it insoluble in water.

Snake venom

is produced by the modified saliva glands of a poisonous snake and is ejected through the fang of the snake.

Saponification

is the reaction of a fat with a strong base such as NaOH in the presence of heat

Glyceryl tripalmitoleate (tripalmitolein)

is the triacylglycerol that contains ester bonds between glycerol and three palmitoleic acids acid molecules.

An oil

is usually liquid at room temperature is usually obtained from a plant source such as palm oil and coconut oil

A fat

is usually solid at room temperature usually comes from animal sources such as meat, whole milk, butter, and cheese

polyunsaturated

linolenic acid

Fatty acids

long, unbranched carbon chains with a carboxylic acid group at the end typically 12- to 18-carbon atoms long insoluble in water because of the long carbon chain

saturated

stearic acid

Functions of prostaglandins

such as lowering or raising blood pressure and stimulating contraction and relaxation of the smooth muscle of the uterus

Unsaturated fats

such as those in vegetable oils and fish are recognized as more beneficial to health than saturated fats.

In commercial hydrogenation,

the addition of hydrogen is stopped before all the double bonds in a liquid vegetable oil become completely saturated the partial hydrogenation of a liquid vegetable oil changes it to a soft, semisolid fat the more saturated product has a higher melting point

In unsaturated fatty acids

the cis double bonds cause the carbon chain to bend or kink, giving the molecules an irregular shape and allowing fewer interactions between molecules.

ester bond with phosphate, which forms another phosphoester bond to choline or ethanolamine

the hydroxyl group forms an

In hydrolysis,

triacylglycerols split into glycerol and three fatty acids a strong acid, HCl or H2SO4, or digestive enzymes called lipases are required

Lecithin and Cephalin

types of glycerophospholipids that are abundant in brain and nerve tissues found in egg yolk, wheat germ, and yeast

unsaturated

when they contain C C double bonds in the carbon chain

saturated

when they do not contain C C double bonds in the carbon chain

block production of prostaglandins,

Nonsteroidal anti-inflammatory drugs (NSAIDs)---- decreasing pain and inflammation.

lipos,

Lipids are named for the Greek word --- which means "fat"

soluble

Lipids are---in organic solvents but not in water

esters

Lipids such as waxes, fats, oils, and phospholipids are ---that can be hydrolyzed to give fatty acids and other molecules.

partial hydrogenation of vegetable oils.

Many soft margarines, stick margarines, and solid shortenings are produced by the

are found on the surface of fruits and on the leaves and stems of plants, where they help prevent loss of water and damage from pests.

Natural waxes

eicosanoids,

Prostaglandins are also known as ---formed from arachidonic acid, a polyunsaturated fatty acid with 20 carbon atoms

forming "soaps" (salts of fatty acids)

Saponification is the process of

glycerol and the sodium salts of fatty acids

Saponification splits triacylglycerols into

KOH

Saponification with ----gives softer, liquid soaps

NaOH

Saponification with ----gives solid soaps that can be molded into different shapes

animal fats and in coconut and palm oils

Saturated fatty acids are usually found in

tristearin.

The common name of this compound, glyceryl tristearate., is

an amino alcohol, phosphoric acid, glycerol, and two fatty acids.

The components of a typical glycerophospholipid:

Lipids

an important feature in cell membranes, fat-soluble vitamins, and steroid hormones

Sphingomyelins

are abundant in the white matter of the myelin sheath, a coating surrounding the nerve cells that increases the speed of nerve impulses and insulates and protects the nerve cells.

Prostaglandins

are hormone-like substances produced in cells are also known as eicosanoids, formed from arachidonic acid, a polyunsaturated fatty acid with 20 carbon atoms differ by the substituents attached to the five-carbon ring have many functions, such as lowering or raising blood pressure and stimulating contraction and relaxation of the smooth muscle of the uterus

In the body, trans fatty acids

behave like saturated fatty acids are estimated to be 2-4% of our total calories raise LDL-cholesterol and lower HDL-cholesterol

Lipids

biomolecules that contain fatty acids or a steroid nucleus

Foods containing naturally occurring trans fatty acids include

milk, eggs, and beef.

polyunsaturated because they contain large amounts of fatty acids with two or more double bonds

oils from corn, cottonseed, safflower seed, and sunflower seed are

monounsaturated; they contain large amounts of oleic acid

oils from olive and peanut are

saturated fatty acids

oils from palm and coconut are solids at room temperature because they consist mostly of

monounsaturated

palmitoleic acid