presentation1 lipids

7/24/2019 Presentation1 Lipids

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hormone like, help regulate blood pressure, clotting, and produce

pain and fever.


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Triglyceride


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Lipids

Lipids:are structurally heterogeneous group of substances of biologicalorigin that are insoluble in water but are soluble in non-polar organicsolvents.

Fatty acids:are mono-carboxylic acids (COOH) that contain long, un-branched hydro-carbon (CH) chains generally 12-2 carbon atomsin

length. !hey are rarely found free in nature but rather occur mostly inesteri"ed form. !hey almost always contain an even numberof carbon

atoms.

Fatty acidscan be classi!edinto "aturatedor #nsaturatedF.$cids:

%&"aturated fatty acids:have a carbon chain in which all carbon-

carbon bonds are single bonds.& #nsaturated fatty acids:

a. 'ono&unsaturated fatty acids# have a carbon chain in whichonecarbon-carbon double bondis present.

b. (olyunsaturated fatty acids# have a carbon chain in which t)oor more carbon-carbon double bond are present.$p to * doublebonds are found in biologically important unsaturated fatty acids.


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%aturated &atty 'cids

un&branched hydro&carbon+CH chains

mono&carbo-yl

icacids

single bonds


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ouble bound

/ink

mono&carbo-ylic

acids

un&branchedhydro&carbon

+CH chains

$nsaturated &atty'cids

0 Carbon $toms


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aturated F.$: "olid at 1.T

#nsaturated F.$: li2ui


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$mphipathic: one end of the

molecule is hydrophilic and theother is hydrophobic


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onounsaturated &. 'cids

olyunsaturated &. 'cids


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"aturated Fatty $cids

monounsaturated Fatty $cids


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3$n omega fatty acid, has two ends, designated as the methyl +CH4 end andthe carbo-yl +COOH end.

$n Omega&4 fatty acids:is a polyunsaturated fatty acid with its endmost double

bond three carbonsaway from its methyl end.linolenic acids

$n Omega&* fatty acid:'n *mega- fatty acids# is a polyunsaturated fatty acidwith its endmost double bond si- carbonsaway from its methyl end.Linoleic

35ssential fatty acids:are fatty acids that are needed by the human body andmust be obtained from dietary sources because they cannot be synthesi+edwithin the body from other substances. !here are two essential fatty acidslinolenic acid (omega- acid) and linoleic acid(omega- acid).oth are %0&carbon polyunsaturated fatty acids.

oth acids contribute to proper membrane structure. hen linoleic acidismissing from diet, the skin reddensand becomes irritated, infectionsand

dehydration are li/ely to occur, and the liver may develop abnormalities. 0fthe fatty acid is restored, then the conditions reverse themselves.

6nfantsare especially in need of linoleic acid (omega-) for their growth.Human breast milkhas much higher percentage of it than co)7s milk.

Omega&4 , Omega&* and5ssential Fatty $cids


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methyl () en

carboxyl (**) en


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Linoleic(omega*) and linolenic acids +Omega4+%0are needed forthe synthesis of other longer&chain poly-unsaturated acids, including#

%&$rachidonic acid +8, the ma3or precursor of 4cosanoids, (hormon li/e)help regulate blood presure, clotting, and produce pain and fever.

&5icosapentaenoic acid +5($+8 and 4&ocosahe-aenoic acid +H$+ are important constituents of the membranes of the brain andare necessary for brain development. 4' and 5' are also activein the retina of the eye.

9egetable oils and meatsprovide omega acidsand !shis a good source of

omega&4 acids. (5at more !sh).

Heart attack rateis much higher in #"$+consume t)ice the amount ofomega&*

!he people of reenlandhave prolonged bleeding time and a high incidenceof stroke. (consume t)ice the amount of omega&4)

&Take balanced food.-(;&%8 grams ofomega&* to % gram ofomega&4)


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(omega-acid)

(omega- acid).

(omega-acid)

%

6

;


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methyl+CH4

nd

carbo-yl +COOH e


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Fats function as energy reservoirs in animals

!he fat content of normal humans allows them to survive starvation for 2 or months

hile human store of glycogen can supply only for one day but carbohydrates are 7uic/

sources for metabolic energy because of water solubility

Fat stores: skin, abdominal cavity and mammary gland Triacylglycerols

Triacylglycerols function to insulate: protect the body from the outerenvironments

9egetable oils: are composed of Triacylglycerol )ith unsaturated fatty acids li2uid at

room tem.

8egetable oils can be into solid by catalytic hydrogenation which reduce the double bonds

to single bonds.

9 4xposure of the lipid rich food to oxygen for long time may spoil and the lipid is said to

be 1ancid. 1ancidity results from the cleavage of double bond in unsaturated F.$ that

produce aldehyde and carboxylic acid(butyric acid) with low .wt bad smell


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Fatty acidshysical and hemical properties

&"olubility: the (hydrophobic) non&polar hydrocarbon chainaccount for the poor solubility of &.'s in water.

9 Carbo-yl group is (Hydrophilic) polarand this account forthe slight solubility of short chain fatty acids in water.

9!he longer the fatty acids and fewer the double bonds, thelower is the solubility in water.

&'elting point: depends on chain length, the degree ofunsaturation.

- 5ouble bonds disrupt intermolecular pac/ing and there forelower melting temperature.

- "aturated F.$s are solidsat :.!emperature. whileunsaturated F.$s are li2uids.

- Fatty acids form micelles

& Fatty acids are )eakly acidic


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mono&carbo-yl

icacids


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9 4xposure of the lipid rich food to oxygen for long time ; may spoiland the lipid is said tobe 1ancid. 1ancidity results from the cleavage of double bondin unsaturated F. $ thatproduce aldehyde and carboxylic acid with low .wt ; bad smell


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In the unsaturated F. A

the cis configuration

double bond forces a kink

(bend) in the hydrocarbon

chain

Unsaturated chains bend

and pack in a less ordered

way, with greater potential

for motion

F.A with one or more kinks cannot

pack together as tightly as fully

saturated F.A and theirinteractions are weaker

So the unsaturated F.As take less

thermal energy to disorder these

poorly ordered arrays of

unsaturated F.As they haelower meltin oints


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Triglyceride

" li id F $ id d T i l l l


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Triacylglycerols: is a compound formed by esteri!cationof threefattyacids to glycerol. 'n acyl group is the group that remains after the


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5stersare carbo-ylic acidderivatives in which the >OH groupof the carbo-ylic acid has been

replaced with an >O1 group

:--O&H :--O-1

O O


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Triacylglycerol +Triglyceride ?4HO

lycerol ? 4 F.$s

$ simple Triacylglycerolhas three identical fatty acid

$ mi-edTriacylglycerolhas three fatty acids+but more than one

kind

$cyl group

CHOH&CHOH&CHOH

%0

%0

%0


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$ mi-ed Triacylglycerol has three fatty acids +butmore than one kind

cyl group

'ost naturally occurring triacylglycerolsare mi-ed ones

@o single triacylglycerolstructure ade2uately describes a

=

%=


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4 $cyl groups

Triacylglycerol


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Fatsandoils# are naturally occurring mixtures of triestersformed from thereaction between three fatty acid molecules and a glycerol(an alcohol)ith three hydro-yl groups).

Fats: are triacylglycerol mixtures that have a relatively highpercentage ofsaturated fatty acids. (Fats are solids).

Oils: are triacylglycerol mixtures that have a relatively highpercentage ofunsaturated fatty acids. (Oils are li2uids).

Alood cholesterol: all current dietary recommendationsstress reducing

saturated fat inta/e. +Autter to margarine or partially hydrogenatedvegetable oils rather than animal fats. owever, recent research suggestthat partially hydrogenated products as bad as saturated fats, oreven )orse, in raising blood cholesterol levels. hy? uringhydrogenation some of the unsaturated double bonds that are naturallypresent in the cis con!guration, are isomeri+ed to the trans con!guration.

$void both transfatty acid +partially hydrogenated vegetable oils likemargarine and

saturated fats +animal fats like butter.

Omega *: +poultry, eggs, avocado, nuts, cereals, whole grain bread, mostvegetable oils, linseed, pump/in seeds)

Omega 4: +linseeds, oily Fish, salmon, HaBel nuts, eggs, meat


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mono&carbo-yl

icacids


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Lo) level of HL Cholesterol predispose to coronary andperipheral arterial disease

LL Lo) ensity Lipids

HL Heavy ensity Lipids


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cis con!guration


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trans con!guration


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(hosphoacylglycerols: are triesters of glycerol in whichtwo


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(hosphatidylcholines: /nown as lecithins . !heen+yme lecithinasein the intestine hydroly+es most ofit when ta/en orally (egg yolk and soybeans). ithinthe body, it is prevalent in the cell membranes. 0t is

made by the liver@ thus are not essential nutrients.6n food industry: are used as emulsi!ersto promote

mixing of otherwise immiscible materials (found in#mayonnaise, ice cream, and custards).

phophatidylethanolamines, and

phosphatidylserines: Anown as cephalins. &ound inheartand liver tissues and in high concentrations inthe brain. !hey are important in blood clotting.

h h l l l


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"tearic acid+%0:8

Oleic acid+%0: %

(hosphatidylcholine

cholin,ethanolamine,orserine

attached tothe phosphategroup

phosphatidylcholines,phophatidylethanola

mines,

Headis polarHydrophilic

T)o tailsarenonpolarHydrophobic

hosphoacylglycerols


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%phingolipids# are ma3or constituents of cell membranes of thebody. !hey have structures based on the long-chain amino dialcohol

sphingosine. (derived from the amino dialcohol sphingosine).

'll lipids derived from sphingosine have

(1) a fatty acid connected to the OH group on the terminal carbon atom viaan ester linkage. 'lso have head and t)o tails.

&orsphingolipids, the fatty acid is one of the tails, and the

long carbon chain of sphingosineitself is the othertail.

!he additional component is the head, and it is phosphoric acid-choline group for particular model shown#

%&"phingomyelins: sphingolipds in which the esterifying group isphosphoric acidto which cholineis attached.

&ound in all cell membranes and are important structuralcomponents of the myelin sheaths , the protective and insulatingcoating that surrounds nerves.


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O

C@H$mide

Oeleased:

from @H

H fromOOH

sphingosine

sphingosine

"phingolpid general structure


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"phingomyelins

phosphoric acid-choline group

head

fatty acid ?

sphingosine

t)o tails

Tails

head


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Cerebrosidesand agliosides: some sphingosine-based membrane lipids have a small carbohydrate

as the head group.

&Cerebrosides, the simplest of suchcarbohydrates&containing lipids, usually have a

glucoseor galactoseas the carbohydrate unit. !hecerebrosides, occur primarily in the brain(


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"tearic acid+fatty acid

%0:8

'onosaccharide

alactose

sphingosine

erebroside "tructure


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Tryglicerides(hosphatidylinositol

(hosphatidylcholine(hosphatidic acid

(hosphatidylethanolamin

(hosphatidylserine

"phingomyelinCerebroside monoanglioside oligo

lycerophosphlipid


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y p p p(hosphatidylcholine

Fatty acids

Fatty acids Fatty acid

choline

choline

"phingomyelin lycolipid

"phingolipid lycolipid


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"teroids:

%& Cholesterol:

& Aile salts:

4& "teroid Hormones:

%& se- hormones:

& adrenocorticalhormones:


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"teroids: are lipids with structures based on afused&ring system involving three si-&

membered rings and one !ve&membered ring.!he fused-ring system of steroids, called a steroidnucleus. 1ings are labeled with letters $,A,C,and each carbon atom is labeled with a number.=umerous steroids have been isolated from plants,animals, and humanbeings. Location of doublebonds within the fused-ring system and thenatureand locationof substituents distinguishone steroid from another. ost steroids have an

o-ygen functional group ( O or >OH) atcarbon 4and some /inds of chain at carbon %


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$lkylside

chain

'ethyl

groupsC%8 C%4

Hydro-yl

groupat C4

'ethyl

groupsin the$lkylsidechain

% Ch l t l i h b d id


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%& Cholesterol: is the most abundant steroidin human body. !he name has


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Human blood plasma containsabout E8 mg of free cholesterol per%88 ml. and about %OH group oncarbon is considered the headof

the molecule, it is small polar headwith limited water solubility.steroidnucleus is the nonpolar part.


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Cholesterolis the starting material + (recursor for thesynthesis of numerous steroid hormones, vitamin , andbile salts. it regulatesthe Fuidity of the cell membrane. %o it

is essential to life,

0n human liver 1 gm is produced each day (bodyGs need).

igh blood cholesterol, high blood pressure and smo/ing are themaor risk factors for cardiovascular disease +C9.

igh blood cholesterol ---atherosclerosis (pla7ue in thearteries)---- hardening of the arteries that serve the heart-----reduced blood Fow to heart muscle -------and can lead toheart attack.

1educe eating animal products (meat, dairy products andfats) eatmore fruitsand vegetables(contains nocholesterol).


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$lkylside

chain

'ethyl

groupsC%8 C%4

Hydro-yl

groupat C4

'ethyl

groupsin the$lkylsidechain

OH group (olar head

steroid nucleus@onpolar part


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& Aile salts: are emulsifying agents that ma/e

dietary lipidssoluble in the a2ueousenvironmentof the digestive tract. 5uringdigestion, bile salts are released into theintestine from the gallbladder, emulsifying(solubiliBing) fatsand oils.

The t)o principle bile salts are#

a. sodium glycocholate (contains glycine) and

b. sodium taurocholate (contains taurine asmodi"ed amino acid).


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4& "teroid Hormones:

ormones# chemical messengers produced by ductless glands. !heyserve as a means of communication between various tissues. =ot allhormones are steroids. Cholesterolis the starting material for the

production of all steroid hormones.lasses # %& se- hormones:

a. 5strogens: the female se- hormones:(in the ovaries).:esponsible for the development of#

&female secondary se- characteristics at the onset of pubertyand for &&regulation of the menstrual cycle. !hey also

&stimulate the development of the mammary glands duringpregnancy

&induce estrus +heat in animal.

b. $ndrogens: the male se- hormones# (testes). romote thedevelopment of secondary male characteristics. !hey alsopromote muscle gro)th.

c. (rogestins: the pregnancy hormones: +ovariesandplacenta.(repare the lining of the uterus for implantation of the fertiliBedovum. !hey also suppress ovulation.

& adrenocortical hormones:

The follo)ing gives the structure of primary hormone in each


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The follo)ing gives the structure of primary hormone in eachof the 4 se- hormones

"ynthetic progestin

(revents ovulation

3

3

6nterferes )ith gestation of a

fertiliBedegg and terminates a

GG

GG

$ synthetic tissue

build steroid


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& $drenocortical hormones:

a. 'ineralocorticoids: control the balance of @a? and/? ions in cells. (

(aldosterol)

b. lucocorticoids: +in adrenal glands

control glucose metabolism and

counteract inammation. +cortisolor hydrocortisol.

rheumatoid arthritis

#sed to control

ntrol the balance of

control glucose


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inammatoryiseases: rheumatoidarthritis

"ynthetic

? and /? ions in cellsmetabolismand counteractinammation

ineralocorticoids lucocorticoids Cortisone (rednisolone$nti&inammatio

Linoleic +omega* and linolenic acids +Omega4


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4icosanoids# derivetives of polyunsaturated 8&carbonfatty acids. $rachidonic acid, 8:; fatty acid is the precursor

of most eicosanoids. (roduced by many cells.!he name isderived from reek wordekos, It)entyJ. 6t is hormone likeeHective at e-tremely lo) concentrations locally.

!he physiological eHects of eicosanoids:

%& The inammatory response, +to tissue damage.

& The production of pain and fever.4& The regulation of blood pressure .

;& The induction of blood clotting.

E& The control of reproduction functions, such as induction oflabor.

*& The regulation of the sleepK)ake cycle.

Linoleic+omega* and linolenic acids +Omega4+%0are needed for the synthesis of other longer&chainpoly&unsaturated acids, including:%&$rachidonic acid +8, the maor precursor ofeicosanoids, +hormon like help regulate blood presure,clotting, and produce pain and fever.

#nsaturated F.$


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There are 4 principle types of eicosanoids:

%& (rostaglandins: raising body temp., inhibit gastric 3uice,relaxing smooth muscle, intensify pain, enhanceinammatory response.

$spirin: inactivateenByme needed forprostaglandinsynthesis.

& Thrombo-anes: (roduced by platelets)-formation of blood clots and

-promotes platelets aggregation.

4& leukotrins: +in AC".

&6nammatoryand hyper sensitivity +allergyresponses are associated with elevated leukotriens.


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$rachidonic acid, 8:;fatty acid

is the precursorof mosteicosanoids


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%& (lasma membranes: all cells are surrounded by plasma membrane that con"nes theircontents. 08Dof the mass of a plasma membrane is lipid material.

0t is a lipid bilayer made up of various phospholipids(phosphoacylglycerolsandsphingolipids). !he nonpolar tails of the lipids are in the middle and the polar heads areon the outside surface. ost lipid molecules in it contain at least one unsaturated fattyacid. !his ma/es kinksin their carbon chains, prevent tight packing of fatty acid chains.(becomes li2uid like) allowing numerous types of biochemicals to pass into and out of acell.

a. Cholesterolregulate membrane Fuidity, "ts between the fatty acid chains restrictingmovements of &.' and ma/ing the membrane more rigid. hile cholesterol adds "rmness andintegrity to the plasma membrane and prevents it from becoming overly Fuid, it also helpsmaintain its Fuidity.

't the high concentrations it is found in our cellIs plasma membranes (close to DB percent,molecule for molecule) cholesterol helps separate the phospholipids so that the fatty acidchains canIt come together and cyrstalli+e.

!herefore, cholesterol helps prevent extremes-- whether too Fuid, or too "rm-- in theconsistency of the cell membrane

b. (roteinsare also components of lipid bilayers, moving substances such as nutrientsandelectrolytesacross the membrane, and also act as receptorsthat bind hormonesandneurotransmitters.

(lasma membranes

kinksin their carbon chains, prevent tightpacking of fattyacidchains.(b li id lik )


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(roteins(roteins

(roteins

(roteins

Cholesterol

moving substancessuch as

nutrientsandelectrolytes

across the membrane

Cholesterol: restrictmovements of &.' and ma/ing

the membrane more rigid

(becomes li2uid like)

lipid bilayer


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/ink


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/ink

/ink

9itamins


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9itamins


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4 active forms in the bod%& retinol& retinal4& retinoic acid;& plant beta&carotene

converted in liver to vit $


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6n 1etinaFunctions of vitamin $% 9isual cycle: 1hodopsin (visual


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6n 1etina

$ll trans retinol

$ll trans retinal

%%&cis retinal

1hodopsin

$ll trans retinal

%& 9isual cycle: 1hodopsin (visualpigment of the rod cells of the retina)consists of#(%%&cis retinal J protein opsin).

hen :hodopsinexposed to light, aseries of photochemical isomeri+ationoccurs, which results in the release of alltrans retinal and opsin.!his causes nerve impulse transmittedby optic nerve to the brain.

:egeneration of :hodopsin#!rans retinal,after being released from :hodopsin, isisomeri+ed to 11-cis retinal, whichspontaneously combines with opsin toform :hodopsin, thus completing thecycle.

& ro)th: 'nimals deprived of vitamin', lose their apetite, their bone growth isslow, their nervous system growth isaHected leading to =% damage.4& 1eproduction: 1etinol and retinalare essential for reproduction, thus,animals given vitamin $only as retinoic

9itamin$ and vision-11-cis retinal is acomponent ofthe visual pigment,rhodopsin.

-

opsin

opsin

5-posed

to light

5rgocalciferol +vit M

lates: Ca? (hosphorous metabolism


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$ctive form of +9it 4%,E&dihydro-ycholecalciferol(romote Ca M phosphorous$bsorption in the intestine

MCholecalciferol +vit4

1ickets:$bnormal boneformation,resulting in skeletaldeformities,muscle pain,enlarged liver andspleen

Cholecalciferol +vit 4


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ha&tocopherol is the most biologically active of other forms of 9itamin

Other forms are: beta, gamma, delta,

. $lso protects vitamin $fromo-idation The most

important locationOf vit 5 is the lung

@e)born have sterile intestinet it f th ilk l


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9itamin / forms:%& in plants: phyllo2uinone

9it /% & in bacteria:

mena2uinone9it / 4& for therapy: synthetic:

menadione

"ource:is dietand intestinalbacteria.

$ntibiotic treatment maylead to hypoprothrombinemia

in malnourished persons

gets it from the milk only

Thrombin

Fibrinogen

Fibrin

rothrombin


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(h h li id


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"torage lipids

Triglyceride

'embrane lipids

"phingolipids

(hospholipids


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%torage lipids embrane lipids hospholipids >lycolipids

%phingolipids


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presentation1 lipids

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