11

AnnouncementsAnnouncements & Agenda& Agenda (04/16/07)(04/16/07)

Pick up QuizzesPick up QuizzesExtra Credit Assignment Due NOW!Extra Credit Assignment Due NOW!Exam Fri 04/20 (Ch 13,14,15)Exam Fri 04/20 (Ch 13,14,15) REVIEW @ 5 pm Wed!!!REVIEW @ 5 pm Wed!!! exam exam will notwill not include pp. 520-524 include pp. 520-524 BTW, “Forms of Carbohydrates” tutorial on CD good for BTW, “Forms of Carbohydrates” tutorial on CD good for

looking at carbohydrate structureslooking at carbohydrate structures

TodayToday Finish fatty acids (15.2)Finish fatty acids (15.2) Triglycerides & reactions (15.3, 15.4)Triglycerides & reactions (15.3, 15.4) Glycerophospholipids (15.5)Glycerophospholipids (15.5) Cholesterol (15.6)Cholesterol (15.6)

22

Last Time: PolysaccharidesLast Time: Polysaccharides

• often polymers of D-glucose.often polymers of D-glucose.• include amylose & amylopectin, include amylose & amylopectin,

starchesstarches made of made of αα-D-glucose.-D-glucose.• include include glycogenglycogen (animal starch (animal starch

in muscle), which is made of in muscle), which is made of αα--D-glucose.D-glucose.

• include include cellulosecellulose (plants and (plants and wood), which is made of wood), which is made of ββ-D--D-glucose.glucose.

α-D-Glucose

O

CH2OH

OHOH

OH

OH

33

The monosacharides in glycogen in The monosacharides in glycogen in are linked by…are linked by…

0%

0%

0%

0%

0%1.1. -1, 4 glycosidic bonds only-1, 4 glycosidic bonds only

2.2. -1, 4 glycosidic bonds only-1, 4 glycosidic bonds only

3.3. -1, 6 glycosidic bonds only-1, 6 glycosidic bonds only

4.4. Contain both Contain both and and glycosidic bonds glycosidic bonds

5.5. None of the aboveNone of the above

11 22 33 44 55

44

Last Time: Intro to Lipids (Fat!)Last Time: Intro to Lipids (Fat!)

55

24 Good Practice Problems (Ch 15)24 Good Practice Problems (Ch 15)

15.05, 15.11, 15.13, 15.19, 15.21, 15.05, 15.11, 15.13, 15.19, 15.21, 15.27, 15.29, 15.31, 15.37, 15.39, 15.27, 15.29, 15.31, 15.37, 15.39, 15.41, 15.43, 15.45, 15.49, 15.51,15.41, 15.43, 15.45, 15.49, 15.51,

15.57, 15.65, 15.67, 15.69, 15.71,15.57, 15.65, 15.67, 15.69, 15.71,

15.73, 15.77, 15.78, 15.81 15.73, 15.77, 15.78, 15.81

Turn in your work for 15 of these by Wed @ 11 am Turn in your work for 15 of these by Wed @ 11 am to receive 1 pt extra creditto receive 1 pt extra credit

66

Last Time: Lipids w/ Fatty AcidsLast Time: Lipids w/ Fatty Acids

• saturated:saturated: all all single Csingle C–C –C bonds.bonds.

• unsaturated:unsaturated: with one or with one or more double more double C=C bonds.C=C bonds.

palmitic acid, a saturated acid

palmitoleic acid, an unsaturated acid

O

C OH

O

C OH

77

Last Time: Unsaturated vs. Last Time: Unsaturated vs. Saturated Fatty AcidsSaturated Fatty Acids

• Unsaturated: contain one or Unsaturated: contain one or more more ciscis double C= double C=C bonds.C bonds.

• have “kinks” in the fatty acid have “kinks” in the fatty acid chains.chains.

• do not pack as closely. do not pack as closely. • have fewer attractions between have fewer attractions between

chains.chains.• have lower melting points.have lower melting points.• are liquids at room temperature.are liquids at room temperature.

COOHH

H CC

HOOC

H

H

C

C

“kinks” in chain

88

15.315.3Waxes, Fats, and Oils Waxes, Fats, and Oils

99

WaxesWaxes• esters of saturated fatty acids and long-esters of saturated fatty acids and long-

chain alcohols.chain alcohols.• coatings that prevent loss of water by coatings that prevent loss of water by

leaves of plants. leaves of plants.

1010

Fats and Oils: TriacylglycerolsFats and Oils: Triacylglycerols

• also called triacylglycerols or also called triacylglycerols or triglyceridestriglycerides

• esters of glycerol.esters of glycerol.• produced by esterification.produced by esterification.• Formed when the hydroxyl Formed when the hydroxyl

groups of glycerol react with groups of glycerol react with the carboxyl groups of fatty the carboxyl groups of fatty acids.acids.

1111

OHCH2

OH

OHCH2

CHO

(CH2)14CH3CHO

O

(CH2)14CH3CHO

O

(CH2)14CH3CHO

Formation of a TriacylglycerolFormation of a Triacylglycerol

glycerol + three fatty acids triacylglycerolglycerol + three fatty acids triacylglycerol

+ 3H+ 3H22OO

O

O

C (CH2)14CH3

CH O

O

C (CH2)14CH3

CH2 O

O

C (CH2)14CH3

CH2

+

1212

(CH2)12CH3

O

C

CH(CH2)7CH3(CH2)7CH

O

C

O

(CH2)16CH3C

O

O

OCH2

CH2

CH

Different Fatty Acids Can Make Different Fatty Acids Can Make Up Triacylglycerols!Up Triacylglycerols!

Stearic acid

Oleic acid

Myristic acid

1313

Melting Points of Fats and OilsMelting Points of Fats and Oils

A A fatfat

• is solid at room temperature.is solid at room temperature.

• is prevalent in meats, whole milk, butter, is prevalent in meats, whole milk, butter, and cheese. (mmm… cheese)and cheese. (mmm… cheese)

An An oiloil

• is liquid at room temperature.is liquid at room temperature.

• is prevalent in plants such as olive and is prevalent in plants such as olive and safflower.safflower.

1414

Oils w/ Unsaturated Fatty AcidsOils w/ Unsaturated Fatty Acids

• have more unsaturated fatshave more unsaturated fats

• have have cis cis double bonds that cause double bonds that cause “kinks” in the fatty acid chains“kinks” in the fatty acid chains

• ““kinks” result in poor packingkinks” result in poor packing

• have lower melting points than have lower melting points than saturated fatty acids.saturated fatty acids.

• are liquids at room temperature.are liquids at room temperature.

1515

Diagram of Triacylglycerol with Diagram of Triacylglycerol with Unsaturated Fatty AcidsUnsaturated Fatty Acids

Unsaturated fatty acid Unsaturated fatty acid chains with kinks cannot chains with kinks cannot pack closelypack closely..

1616

Percent Saturated and Unsaturated Fatty Percent Saturated and Unsaturated Fatty Acids In Fats and OilsAcids In Fats and Oils

1717

The chemical reactions of triacylglycerols are The chemical reactions of triacylglycerols are similar to those of alkenes and esters. similar to those of alkenes and esters.

• HydrogenationHydrogenation of double bonds in unsaturated of double bonds in unsaturated fatty acids by Hfatty acids by H22 (compare to alkenes) (compare to alkenes)..

• HydrolysisHydrolysis of ester bonds by water in the of ester bonds by water in the presence of an acid, a base, or an enzyme presence of an acid, a base, or an enzyme (compare to esters).(compare to esters).

15.4 Chemical Properties of Triacylglycerols15.4 Chemical Properties of Triacylglycerols

1818

Hydrogenation of OilsHydrogenation of Oils

• adds Hadds H22 to the to the

carbon atoms of carbon atoms of double bonds.double bonds.

• increases the increases the melting point.melting point.

• produces solids produces solids such as margarine such as margarine and shortening. and shortening.

1919

CH(CH2)7CH3(CH2)5CH

O

C

CH(CH2)7CH3(CH2)5CH

O

C

CH(CH2)7CH3(CH2)5CH

O

C

O

O

OCH2

CH2

CH

HydrogenationHydrogenation

+ 3H+ 3H2 2 NiNi

glyceryl tripalmitoleateglyceryl tripalmitoleate (tripalmitolean)(tripalmitolean)

glyceryl tripalmitateglyceryl tripalmitate(tripalmitin)(tripalmitin)

O

(CH2)14CH3C

O

(CH2)14CH3C

O

(CH2)14CH3C

O

O

OCH2

CH2

CH

2020

Olestra, A Fat SubstituteOlestra, A Fat Substitute

• used in foods as an artificial fat.used in foods as an artificial fat.• sucrose linked by ester bonds to several sucrose linked by ester bonds to several

long-chain fatty chains.long-chain fatty chains.• not broken down in the intestinal tract.not broken down in the intestinal tract.

2121

Olestra (WOW or Light)Olestra (WOW or Light)

http://en.wikipedia.org/wiki/Olestrahttp://en.wikipedia.org/wiki/Olestra

Launched in 1996 as WOW potato chips ($400 Launched in 1996 as WOW potato chips ($400 mil in 1998). Fell to $200 mil when FDA mil in 1998). Fell to $200 mil when FDA restricted the label to state “may cause restricted the label to state “may cause abdominal cramping and loose stools”. It also abdominal cramping and loose stools”. It also inhibited absorption of Vitamins A, D, E and Kinhibited absorption of Vitamins A, D, E and K

It is made from one sucrose and 8 oleic acid It is made from one sucrose and 8 oleic acid molecules. The molecule is so large that it could molecules. The molecule is so large that it could not migrate past the intestinal wallnot migrate past the intestinal wall

2222

CisCis and and TransTrans Fatty Acids Fatty Acids

Unsaturated fatty acids can be Unsaturated fatty acids can be • ciscis with bulky groups on same side of C=C. with bulky groups on same side of C=C.CHCH33─ (CH─ (CH22))55 (CH(CH22))77── COOH COOH ciscis

C=CC=C H HH H

• transtrans have bulky groups on opposite sides of C=C. have bulky groups on opposite sides of C=C.

CHCH33─ (CH─ (CH22))55 HH

C=C C=C transtrans

H H (CH(CH22))77── COOHCOOH

2323

Hydrogenation & Trans Fatty AcidsHydrogenation & Trans Fatty Acids

Most naturally occurring fatty acids have Most naturally occurring fatty acids have cis double bonds!cis double bonds!

• However, during hydrogenation, some However, during hydrogenation, some cis cis double double bonds are converted to bonds are converted to trans trans double bonds.double bonds.

• In the body, In the body, trans trans fatty acids behave like saturated fatty acids behave like saturated fatty acids. Why? fatty acids. Why?

• It is estimated that 2-4% of our total Calories is in It is estimated that 2-4% of our total Calories is in the form of the form of transtrans fatty acid. fatty acid.

• Several studies reported that Several studies reported that transtrans fatty acids raise fatty acids raise LDL-cholesterol and lower HDL-cholesterol.LDL-cholesterol and lower HDL-cholesterol.

2424

HydrolysisHydrolysis

• triacylglycerols split into glycerol and three fatty triacylglycerols split into glycerol and three fatty acids.acids.

• an acid or enzyme catalyst is required.an acid or enzyme catalyst is required.

OCH2

OCH

OCH2

OHCH2

OHCH

OHCH2

O

(CH2)14CH3CHO

H2OO

(CH2)14CH3C

O

(CH2)14CH3C

O

(CH2)14CH3C

H+

+

+

2525

OH

CH OH

CH2 OH

CH2

Saponification (Base Hydrolysis)Saponification (Base Hydrolysis)

O

O

C (CH2)14CH3

CH O

O

C (CH2)14CH3

CH2 O

O

C (CH2)14CH3

CH2

+ 3NaOH+ 3NaOH

Na+ -O

O

C (CH2)14CH333+

“soap”

2626

• the most abundant lipids in cell membranes. the most abundant lipids in cell membranes. • composed of glycerol, two fatty acids, composed of glycerol, two fatty acids,

phosphate, and an amino alcohol.phosphate, and an amino alcohol.

Glycerol

PO4Amino alcohol

15.5 Glycerophospholipids15.5 Glycerophospholipids

Fatty acid

Fatty acid

2727

Polarity of GlycerophospholipidsPolarity of Glycerophospholipids

A A glycerophospholipidglycerophospholipid has has • 2 nonpolar fatty acid chains.2 nonpolar fatty acid chains.• A phosphate group and a polar amino alcohol.A phosphate group and a polar amino alcohol. CHCH33

││+ ++ +

HOHO−CH−CH22−CH−CH22−N−CH−N−CH3 3 HOHO−CH−CH22−CH−CH22−NH−NH33

││ cholinecholine CH CH3 3 ethanolamineethanolamine

++

NHNH33

│ │ Amino alcoholsAmino alcohols HOHO−CH−CH22−CH−COO−CH−COO−−

serineserine

2828

Structure and Polarity of A Structure and Polarity of A GlycerophospholipidGlycerophospholipid

2929

LecithinLecithin and and cephalincephalin are glycerophospholipids are glycerophospholipids• abundant in brain and nerve tissues.abundant in brain and nerve tissues.• found in egg yolk, wheat germ, and yeast.found in egg yolk, wheat germ, and yeast.

Lecithin & CephalinLecithin & Cephalin

3030

CH3

CH3CH3

CH3

HO

CH3

15.6 Steroids: Cholesterol, & 15.6 Steroids: Cholesterol, & Steroid HormonesSteroid Hormones

3131

Steroid NucleusSteroid Nucleus

Consists of:Consists of:

• 3 cyclohexane rings.3 cyclohexane rings.

• 1 cyclopentane ring.1 cyclopentane ring.

• no fatty acids.no fatty acids.

steroid nucleussteroid nucleus

3232

CholesterolCholesterol

• is the most abundant steroid in the body. is the most abundant steroid in the body.

• has methyl CHhas methyl CH33- groups, alkyl chain, and -- groups, alkyl chain, and -

OH attached to the steroid nucleus.OH attached to the steroid nucleus.

CH3

CH3CH3

CH3

HO

CH3

3333

Cholesterol in the BodyCholesterol in the Body

• is obtained from meats, is obtained from meats, milk, and eggs. milk, and eggs.

• is synthesized in the liver.is synthesized in the liver.• is needed for cell is needed for cell

membranes, brain and membranes, brain and nerve tissue, steroid nerve tissue, steroid hormones, and Vitamin D.hormones, and Vitamin D.

• clogs arteries when high clogs arteries when high levels form plaque.levels form plaque.

An artery clogged by cholesterol plaque

A normal, open artery.

3434

Cholesterol in FoodsCholesterol in Foods

• is considered is considered elevated if elevated if plasma plasma cholesterol cholesterol exceeds 200 exceeds 200 mg/dL.mg/dL.

• is synthesized is synthesized in the liver and in the liver and obtained from obtained from foods.foods.

3535

Lipoproteins: LDL, HDL, Etc…Lipoproteins: LDL, HDL, Etc…

• combine lipids combine lipids with proteins & with proteins & phospholipids.phospholipids.

• are soluble in are soluble in water because water because the surface the surface consists of polar consists of polar lipids.lipids.

3636

Types of LipoproteinsTypes of Lipoproteins

• differ in density, composition, and function.differ in density, composition, and function.• include low-density lipoprotein (LDLs) and include low-density lipoprotein (LDLs) and

high-density lipoprotein (HDLs).high-density lipoprotein (HDLs).

3737

Transport of Lipoproteins in the BodyTransport of Lipoproteins in the Body