Lipids Timberlake 1 [Compatibility Mode]

8/16/2019 Lipids Timberlake 1 [Compatibility Mode]

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Lipids

Lipids

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Copyright © 2007 by Pearson Education, Inc.

Publishing as Benjamin Cummings


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Lipids

Lipids are Biomolecules that contain fatty acids or a steroid

nucleus.

Soluble in an organic solvents (e.g., ether, benzene,

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, . Named for the Greek word lipos, which means “fat.” Extracted from cells using organic solvents.


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Nutritional Uses of Lipids We already know that lipids are concentrated sources

of energy (9.45 kcal/g)

other functions:

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1) provide means whereby fat-soluble nutrients (e.g.,sterols, vitamins) can be absorbed by the body2) structural element of cell, subcellular components

3) components of hormones and precursors for prostaglandin synthesis


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Types of Lipids

The types of lipids containing fatty acids are Waxes. Fats and oils (triacylglycerols). Glycerophospholipids.

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Prostaglandins. Not steroids, as they do not contain fatty acids.


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Lipid Classes

Simple : FA’s esterified with glycerol Compound : same as simple, but with other

compounds also attached

Phospholipids : fats containing phosphoric acid and

Glycolipids : FA’s compounded with CHO, but no N derived lipids : substances from the above derived by

hydrolysis Sterols : large molecular with alcohols found in

nature and combined w/FA’s (e.g., cholesterol)

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1. Fatty Acids

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Fatty Acids

Fatty acids Are long-chain

carboxylic acids.

Typically contain 12-18

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. Are insoluble in water. Can be saturated or

unsaturated.

Copyright © 2007 by Pearson Education, Inc.Publishing as Benjamin Cummings


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Fatty Acid Formulas

The formulas for fatty acids are written as Condensed formulas.

Line-bond formulas. For exam le ca r lic acid with 8 carbon atoms.

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CH3—(CH2)6—COOH

CH3—CH2—CH2—CH2—CH2—CH2—CH2—COOH

OH

O


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Saturated fatty acids have Single C–C bonds. Molecules that fit closely together

in a regular pattern.

Saturated Fatty Acids (SFA)

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Strong attractions between fattyacid chains.

High melting points that make

them solids at room temperature.

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Some Saturated Fatty Acids

11Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings


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Structure of Fatty Saturated

- C - OH

O

Benzoic acid

- C - O HO

OH Slicilic acid


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Unsaturated Fatty Acids

Unsaturated fatty acids Have one or more double C=C bond Typically contain cis double bonds.

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Structure of Unsaturated Acid

Oleic acid (C18: 1)


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Properties of Unsaturated Fatty Acids

Unsaturated fatty acids Have “kinks” in the fatty

acid chains.

Do not pack closely.

“kinks” inchain

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between chains. Have low melting points. Are liquids at room

temperature.




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Unsaturated Fatty Acids(The double bonds in the fatty acids are cis (hydrogen atoms are on the same

side of the double bonds of the carbon chain)

❍ Oleic acid (18:1) is a monounsaturated fatty acid

C H3(C H2)7 C C (C H2)7 C

O

OH

❍ Linoleic acid (18:2) is a polyunsaturated fatty acid (one of theomega-6 fatty acids since there is a double bond six carbons from the end of the chain)

C H3(C H2)4 C

H

C

H

C H2 C

H

C

H

(C H2)7 C

O

OH

H H

C


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Comparing Melting Points of Some

Fatty Acids

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Learning Check

Assign the melting points of –17°C, 13°C, and 69°Cto the correct fatty acid. Explain.

stearic acid (18 C) saturated

oleic acid (18 C) one double bond

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linoleic acid (18 C) two double bonds


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Solution

Stearic acid is saturated and would have a higher melting point than the unsaturated fatty acids.Because linoleic has two double bonds, it would have

a lower mp than oleic acid, which has one double

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.stearic acid mp 69°C saturatedoleic acid mp 13°Clinoleic acid mp -17°C most unsaturated


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1a. Prostaglandins

Prostaglandins have

20 carbon atoms in their fatty acid chains.

An OH on carbon 11 and 15.

A trans double bond at carbon 13.

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C 11C 15C 13


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O

O H

Prostaglandins

❍ Prostaglandins are powerful hormones in mammalian systems Prostaglandins were first isolated from the prostate gland (seminal

fluid)❍ Prostaglandins have a five-membered ring with a 7-carbon side chain

(often ending in a carboyxlic acid group) adjacent to an 8-carbon chain


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Prostaglandins in the Body

Prostaglandins are Produced by injured

tissues.

Involved in pain,

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,inflammation.

Not produced whenanti-inflammatory

drugs such as aspirininhibit their synthesis.




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Omega-6 and Omega 3- Fatty Acids

Fatty acids In vegetable oils are mostly omega-6 with

the first C=C at C6.linoleic acid

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CH3 ─(CH2)4 ─CH=CH─CH2 ─CH=CH─(CH2)7 ─COOH6

In fish oils are mostly omega-3 with the

first C=C at C3.linolenic acidCH3 ─CH2 ─(CH=CH─CH2)3 ─(CH2)6 ─COOH

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Copyright © 2007 by Pearson Education, Inc.Publishing as Benjamin Cummings


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Some Omega-6 and Omega-3

Fatty Acids

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Solution

Write a fatty acid with 10 carbon atoms that is: A. saturated

CH3—CH2—CH2—CH2—CH2—CH2—CH2—CH2—CH2—COOH

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B. monounsaturated omega-3CH3—CH2—CH=CH—CH2—CH2—CH2—CH2—CH2—COOH

C. monounsaturated omega-6CH3—CH2—CH2—CH2—CH2—CH=CH—CH2—CH2—COOH


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2. Waxes, Fats, and Oils

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2a. Waxes

Waxes are Esters of saturated fatty acids and long-chain alcohols. Coatings that prevent loss of water by leaves of plants.

TABLE 1.

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Jojoba (Simmondsia sinensis)

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www.kerfootgroup.co.uk


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Fats and Oils: Triacylglycerols

Fats and oils are Also called triacylglycerols. Esters of glycerol. Produced by esterification.

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Formed when the hydroxylgroups of glycerol react with thecarboxyl groups of fatty acids.




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In a triacylglycerol, Glycerol forms ester bonds with three fatty acids.

2b. Triacylglycerols

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Formation of a Triacylglycerol

glycerol + three fatty acids triacylglycerol

OHCH2

O

O

(CH2)14CH3CHO

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OHCH2

O

(CH2)14CH3CHO

2 14 3

+ 3H2O

O

O

C (CH2)14CH3

CH O

O

C (CH2)14CH3

CH2 O

O

C (CH2)14CH3

CH2

+


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Olive Oil

Olive oil Contains a high

percentage of oleic

acid, which is a

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acid with one cisdouble bond.



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Learning Check

What are the fatty acids in the following triacylglycerol?

O

(CH2)16CH3COCH

2

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R1= C18R2= C18 (1) MUFA= mono unsaturated fatty acidR3= C14

(CH2)12CH3

O

C

CH(CH2)7CH3(CH2)7CHC

O

O

CH2

CH


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Solution

Stearic acid

O

O

(CH2)16CH3COCH2

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Oleic acid

Myristic acid(CH2)12CH3

O

C


O

O

CH2

CH


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Melting Points of Fats and Oils

A triacylglycerol that is a fat Is solid at room temperature. Is prevalent in meats, whole milk, butter, and cheese.

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A triacylglycerol that is an oil Is liquid at room temperature. Is prevalent in plants such as olive and safflower.


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Oils with Unsaturated Fatty Acids

Oils

Have more unsaturated fats. Have cis double bonds that cause “kinks” in the

fatty acid chains.

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Cannot pack triacylglycerol molecules as closetogether as in fats.

Have lower melting points than saturated fats.

Are liquids at room temperature.


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Diagram of Triacylglycerol with


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Unsaturated fatty acidchains have kinks thatdo not allow closepacking.



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Safflower (Carthamus tinctorius)

Canola, Rapeseed (Brassica napus L.)

diaryofanutritionist.com

burcon.ca

. .


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Palm kernel oil


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Castor oil (minyak jarak) Ricinus communis Sesame oil (minyak wijen) Kapok seed oil (minyak biji randu/kapok)

Rice bran oil (minyak dedak) Fish oil (minyak ikan)


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Komposisi asam lemak dalam minyak wijen:[1]

Asam lemak minimum maksimum

Asam palmitat C16:0 7,0 % 12,0 %

As palmitoleat C16:1 sangat kecil 0,5 %

Asam stearat C18:0 3,5 % 6,0 %

Asam oleat C18:1 35,0 % 50,0 %

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Asam linoleat C18:2 35,0 % 50,0 %

Asam linolenat C18:3 sangat kecil 1,0 %

Asam eikosenoat C20:1 sangat kecil 1,0 %


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Saturated and Unsaturated Fatty Acids

in Fats and Oils

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Chemical Properties of

Triacylglycerols

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The chemical reactions of triacylglycerols are similar

to those of alkenes and esters.

In hydrogenation, double bonds in unsaturatedfatt acids react with H in the resence of a Ni or

Chemical Properties of Triacylglycerols

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Pt catalyst.

In hydrolysis, ester bonds are split by water in thepresence of an acid, a base, or an enzyme.


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Hydrogenation of Oils

The hydrogenation of oils

Adds hydrogen (H2) to the carbon atoms of double bonds.

Converts double bonds to single bonds.

Increases the melting point.

Produces solids such as margarine and shortening.

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Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings


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Hydrogenation

Ni

+ 3H2

CH(CH2)7CH3(CH2)5CH

O

C

CH(CH2)7CH3(CH2)5CH

O

C

O

OCH2

CH

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glyceryl tripalmitoleate(tripalmitolean)

glyceryl tripalmitate(tripalmitin)

O

(CH2)14CH3C

O

(CH2)14CH3C

(CH2)14CH3C

O

O

OCH2

CH2

CH

CH(CH2)7CH3(CH2)5CH

O

COCH2


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What product(s) is obtained from the completehydrogenation of glyceryl trioleate?

1. Glycerol and 3 oleic acids

Learning Check

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2. Glyceryltristearate3. Glycerol and 3 stearic acids


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What product(s) is obtained from the completehydrogenation of glyceryl trioleate?

2. Glyceryltristearate

Solution

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Olestra, a Fat Substitute

Olestra is Used in foods as an artificial fat. Sucrose linked by ester bonds to several long-chain

fatty chains.

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.



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Cis and Trans Fatty Acids

Unsaturated fatty acids can be Cis with bulky groups on same side of C=C.

CH3 ─ (CH2)5 (CH2)7 ─ COOH cis

C=C

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H H

Trans have bulky groups on opposite sides of C=C.CH3 ─ (CH2)5 H

C=C transH (CH2)7 ─ COOH


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Trans Fatty Acids and

Hydrogenation

Trans fatty acids

Are formed during hydrogenation when cis doublebonds are converted to trans double bonds.

In the body behave like saturated fatty acids.

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Are estimated to make up 2-4% of our totalCalories.

Are reported in several studies reported to raise

LDL-cholesterol and lower HDL-cholesterol.


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Learning Check

(1) True or (2) False

A. There are more unsaturated fats in vegetable oils.

B. Vegetable oils have higher melting points than fats.

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C. Hydrogenation of oils converts some cis-doublebonds to trans- double bonds.

D. Animal fats have more saturated fats.


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Solution

(1) True or (2) False

A. T There are more unsaturated fats in vegetable oils.

B. F Vegetable oils have higher melting points than fats.

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. y rogena on o o s conver s some c s- ou ebonds to trans- double bonds.

D. T Animal fats have more saturated fats.


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Hydrolysis

In hydrolysis, Triacylglycerols split into glycerol and three fatty acids. An acid or enzyme catalyst is required.

O

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OCH2

OCH

O2

OHCH2

OHCH

OHCH2 O

(CH2)14CH3CHO

H2O

O

(CH2)14CH3C

O

(CH2)14CH3C

(CH2)14CH3C

H++3

+ 3


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Saponification and Soap

Saponification Is the reaction of a fat with a strong base. Splits triacylglycerols into glycerol and the salts of

fatty acids.

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s e process o orm ng soaps sa s o a yacids).

With KOH gives softer soaps.


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Saponification

O

O

C (CH2)14CH3

CH O

O

C (CH2)14CH3

CH2

+ 3NaOH

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CH2 O

O

C (CH2)14CH3

Na+ -OOC (CH2)14CH33

OH

CH OH

CH2 OH

CH2

+“soap”


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What products are obtained from the completehydrolysis of glyceryl trioleate?1. Glycerol and 3 oleic acids

2. Glyceryl tristearate

Learning Check

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3. Glycerol and 3 stearic acids


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What products are obtained from the completehydrolysis of glyceryl trioleate?1. Glycerol and 3 oleic acids

Solution

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Learning Check

Write the product of the following reaction.

OCH2 CH(CH ) CH(CH2)5CH

O

C

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O

O

CH2

CH

O


O

C CH(CH2)7CH3(CH2)5CH

H2Ni

+ 3


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Solution

OCH2

O

(CH2)14CH3

O

C

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O

O

CH2

CH

(CH2)14CH3

O

C

(CH2)14CH3C


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Glycerophospholipids are The most abundant lipids in cell membranes. Composed of glycerol, two fatty acids, phosphate

and an amino alcohol.

2c. Glycerophospholipids

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Glycerol

PO4Amino

alcohol

Fatty acid

Fatty acid


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Glycerophospholipids Are Polar

A glycerophospholipid has Two nonpolar fatty acid chains. A phosphate group and a polar amino alcohol.

CH3

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+ +HO−CH2−CH2−N−CH3 HO−CH2−CH2−NH3

│choline CH3 ethanolamine

+NH3│ Amino alcohols

HO−CH2−CH−COO−serine


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Structure and Polarity of A

Glycerophospholipid

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Lecithin and cephalin are glycerophospholipids Abundant in brain and nerve tissues. Found in egg yolk, wheat germ, and yeast.

Lecithin and Cephalin

67Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings


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Learning Check

Identify each as a A. fatty acid B. triacylglycerolC. amino alcohol D. glycerophospholipid

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1. glyceryl trioleate2. cephalin3. choline4. palmitic acid


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Solution

Identify each as a A. fatty acid B. triacylglycerolC. amino alcohol D. glycerophospholipid

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1. glyceryl trioleate B. triacylglycerol2. cephalin D. glycerophospholipid3. choline C. amino alcohol4. palmitic acid A. fatty acid


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Learning Check

Identify the components and type of glycerophospholipidO║

CH2−O −C −(CH2)16 −CH3

O

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CH2−O −C −(CH2)16 −CH3+

O NH3

║ │CH2−O −P −O − CH2−CH−COO-

│O-


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Solution

Identify the components and type of glycerophospholipidO║

CH2−O −C −(CH2)16 −CH3

O 2 stearic acids

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CH2−O −C −(CH2)16 −CH3+

O NH3║ │ type = cephalin

CH2−O −P −O − CH2−CH−COO-│ serineO-

phosphate amino alcohol


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3a. Sphingolipids

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Sphingolipids

Sphingolipids Are similar to phospholipids. Contain sphingosine (a long-chain amino alcohol), a

fatty acid, phosphate, and a small amino alcohol.

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ave po ar an nonpo ar reg ons.

sphingosine

PO4amino

alcohol

fatty acid


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Sphingosine

Sphingosine is a long-chain unsaturated amino alcohol.

CH3−(CH2)12 −CH=CH−CH−OH

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CH−NH2│

CH2−OH

sphingosine


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3b. Glycosphingolipids

Glycosphingolipidscontainmonosaccharidesbonded to the –OH

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glycosidic bond.



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Glycosphingolipids and

Cerebrosides

Glycosphingolipids Are sphingolipids that contain

monosaccharides. Can be a cerebroside with galactose.

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Gangliosides

Gangliosides Are similar to cerebrosides, but contain two or

more monosaccharides. Are important in neurons.

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. Can accumulate and cause genetic diseases.


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Gangliosides

GM2 is a ganglioside That accumulates in Tay-Sachs disease.



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Lipid Diseases (Lipidoses)

In many lipid diseases, the deficiency of an enzymecauses the accumulation of glycolipids.

Table 2.

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Learning Check

Identify each as a1) Fatty acid 2) Triacylglycerol3) Amino alcohol 4) Glycerophospholipid

5) Glycosphingolipid

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. ycery r o ea eB. CephalinC. CholineD. GalactocerebrosideE. Palmitic acid


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Solution

A. Glyceryl trioleate 2) TriacylglycerolB. Cephalin 4) Glycerophospholipid

C. Choline 3) Amino alcohol

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. a ac ocere ros e ycosp ngo pE. Palmitic acid 1) Fatty acid


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4. Steroids

Steroids: Cholesterol, Bile Salts,

and Steroid Hormones

8383

CH3

CH3CH3

CH3

HO

CH3




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Steroid Nucleus

A steroid nucleus consists of

3 cyclohexane rings.

1 cyclopentane ring.

No fatty acids.

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steroid nucleus


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Cholesterol

Cholesterol Is the most abundant steroid in the body. Has methyl CH3- groups, alkyl chain, and -OH

attached to the steroid nucleus.

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CH3

CH3CH3

CH3

HO

CH3


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Cholesterol in the Body

Cholesterol in the body Is obtained from meats,

milk, and eggs.

Is synthesized in the liver.

A normal, open artery.

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s nee e or cemembranes, brain andnerve tissue, steroidhormones, and Vitamin D.

Clogs arteries when highlevels form plaque.



An artery clogged bycholesterol plaque


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Cholesterol in Foods

Cholesterol is Synthesized in

the liver.

Obtained from

Table 3.

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. Considered

elevated if plasma

cholesterolexceeds 200mg/dL.



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Learning Check

Match the components of the cholesterol molecule withthe following:

___ carbon chain ___hydroxyl group

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___ ___

CH3

CH3CH3

CH3

HO

CH3

AC

B

D


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Solution

Match the components of the cholesterol molecule withthe following:D carbon chain A hydroxyl group

C steroid nucleus B methyl group

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CH3

CH3CH3

CH3

HO

CH3

AC

B

D


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Bile Salts

Bile salts

Are synthesized in the liver from cholesterol.

Are stored in the gallbladder.

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.

Have a polar and a nonpolar region

Mix with fats to break them part.

Emulsify fat particles to provide large surface area.


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Bile Salts

COO- Na+CH2

N

O

COH

CH3

CH3

glycine, an amino acidcholic acid, a bile acid

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OHHO

CH3

sodium glycocholate, a bile salt

Nonpolar region

Polar region


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Lipoproteins

Lipoproteins

• Combine lipids with proteins and phospholipids.

• Are soluble in water because the surface consists of polar

lipids.


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Types of Lipoproteins

Lipoproteins Differ in density, composition, and function. Include low-density lipoprotein (LDLs) and high-

density lipoprotein (HDLs).

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Table 4.



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Transport of Lipoproteins in the Body

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Steroid Hormones

Steroid hormones

Are chemical

messengers in cells.

Are produced from


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.

Include sex hormones

such as androgens

(testosterone) in males

and estrogens(estradiol) in females.


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Adrenal Corticosteroids

Adrenal corticosteroids are steroid hormones that Are produced by the adrenal glands located on

the top of each kidney.

Include aldosterone, which regulates electrolytes

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and water balance by the kidneys. Include cortisone, a glucocorticoid, which

increases blood glucose level and stimulates thesynthesis of glycogen in the liver.


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Adrenal Corticosteroids

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Anabolic Steroids

Anabolic steroids Are derivatives of testosterone. Are used illegally to increase muscle mass. Have side effects including fluid retention, hair growth,

slee disturbance and liver dama e.

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Learning Check

Identify each as a1. fatty acid 2. steroid 3. triacylglycerol4. phospholipid 5. sphingolipid

A. cholesterol

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B. glycerol, 2 fatty acids, phosphate, and cholineC. glyceryl tristearateD. sphingosine, fatty acid, phosphate, and choline

E. estradiolF. bile saltsG. lipids in plasma membranes


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Solution

A. cholesterol 2 steroidB. glycerol, 2 fatty acids, phosphate, and choline

4 phospholipidC. glyceryl tristearate 3 triacylglycerol

D. s hin osine fatt acid hos hate and choline

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5 sphingolipidE. estradiol 2 steroidF. bile salts 2 steroidG. lipids in plasma membranes

4 phospholipid, 5 sphingolipid

.


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Cell Membranes

Cell membranes Separate cellular contents from the external

environment.

Consist of a lipid bilayer made of two rows of

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p osp o p s. Have an inner portion made of the nonpolar tails of

phospholipids with the polar heads at the outer and inner surfaces.

Fluid Mosaic Model of Cell


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Fluid Mosaic Model of Cell

Membranes

The lipid bilayer Contains proteins, carbohydrates, and

cholesterol.

Has unsaturated fatty acids that make cell

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membranes fluid-like rather than rigid. Has proteins and carbohydrates on the surface

that communicate with hormones andneurotransmitters.


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Transport Through Cell

Membranes

The transport of substances through cell

Membranes involves

Diffusion (passive transport), which moves

articles from a hi her to a lower concentration.

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Facilitated transport, which uses protein channelsto increase the rate of diffusion.

Active transport, which moves ions against a

concentration gradient.

Transport Pathways Through Cell


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Transport Pathways Through Cell

Membranes



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Learning Check

The transport of particles across a cell membrane fromhigh concentration to low concentration is called

1. Facilitated transport

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2. Diffusion3. Active transport


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Solution

The transport of particles across a cell membrane fromhigh concentration to low concentration is called

2. Diffusion

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References

http://www.kerfootgroup.co.uk/oil-inventory/jojoba-wax

Documents

Lipids Timberlake 1 [Compatibility Mode]