b4 lipids lidia, kate c, nadege, nidah, athina, nikki

8/2/2019 B4 Lipids Lidia, Kate C, Nadege, Nidah, Athina, Nikki

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Chemistry Summer

Assignment : LipidsBy: Lidia Kim, Kate Cutting,

Nadege Assassi, Nidah Khakoo,

Athina Krimitzi and NikiRomanzi


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Objective B.4.1Compare the Composition of the

Three Types of Lipids Found in

the Human Body

By: Lidia Kim


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Background

Glycerol

Has 3 OH groups (tri-ol)

Fatty Acid

16-22 Carbons

A type of carboxyl acid

R-COOH

Phosphate Group


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Triglycerides

Composed of: 1 glycerol + 3 fatty acids If the 3 fatty acids are the same its a simple

triglyceride, if different then mixedtriglyceride.

Formed by the condensation reactionbetween propane-1,2,3-triol and longchain carboxylic acids.(ie. Glycerol andfatty acids :P)

Oils (polyunsaturated): two or more

double bonds Fats (saturated): No double bonds,

saturated (with H) carboxyl groups


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(saturated) (unsaturated)


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Phospholipids A back bone (glycerol) 2 fatty acids (hydrophobic)

Phosphate group (hydrophilic)amphipathic

Function: plasma

membrane, source of

cholinefor making

acetylcholine (nerve

chemical transmitter.)


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The phosphateis derived froman alcoholsuch ascholine or

ethanolamine.*

*Ex.lecithin contains choline as

the side chain.

O2 in the phosphate makethe region around themnegative (phosphate partof the molecule is polar).Polar molecules are

hydrophilic

The fatty acid

tails arenonpolar andhydrophobic


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Steroids Belong to groups of steroids called

sterols

Composed of: 3cyclohexane (6c)rings with one cyclopentane (5C)rings (No fatty acids)

Skeleton can change from

addition of side chains

Function: establish extent ofmembrane permeability in cellmembranes (hydrocarbonembedded in membrane with

fatty acids, and hydroxyl group onthe outside), manufactureshormones


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Objective B.4.2Outline the difference between

HDL and LDL cholesterol and

outline its importance.

By: Kate Cutting


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Lipoproteins Lipoproteins are composed of lipids

(fats) and proteins

Cholesterol is insoluble in water and

substances such as blood

This means Cholesterol molecules

cannot move around themselves in the

blood

Lipoproteins transport lipids and

cholesterol Protein is soluble in water and blood

so they form an outer layer aroundthe cholesterol with the lipid parttowards the cholesterol


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HDL Cholesterol HDL (High Density Lipoprotein) Cholesterol is GOOD

Cholesterol

Has less lipid so it can transport more cholesterol awayfrom the arteries and to the liver where it is broken down

Is more dense than LDL because it contains higherproportion of protein

Can eliminate LDL Cholesterol


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LDL Cholesterol Carry cholesterol to build and repair

damaged tissue so a little bit is not bad

LDL (Low Density Lipoprotein)

Cholesterol is BAD Cholesterol

Transports cholesterol to arteriesstarting the formation of plaque and

blocking blood pathway

Less dense than than HDL due to a

lower proportion of proteins HDL is 45-50% protein, LDL is

25% protein


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Increased levels of

LDL cholesterol is

associated with

atherosclerosis Leads to heart

attack, stroke,

etc.


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Objective B.4.3Describe the difference in

structure between saturated and

unsaturated fatty acids.

By: Nadege Assassi


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Unsaturated Fats Have C=C bonds Monounsaturated vs. Polyunsaturated

Mono: 1 C=C bond

Poly: multiple C=C bonds

C=C bonds create bends in the molecules This minimizes flexibility of the fatty acids, preventing themolecules from aligning closely

Create less dense molecules, making them more reactive andable to break down more easily

Relatively low density means less intermolecular forces andlower melting points

Liquid at room temperature

Less single bondsmolecules packing less denselylesscollisionsless van der waals forceslower melting point


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Saturated Fats Have no C=C bonds

All single C-C or C-H bonds

Not very reactive

Greater intermolecular bonds

More van der Waals forces can occur whensaturated chains lie alongside one another, becausecontact surface area is maximized

High melting points due to greater

intermolecular bonds Solid at room temperature


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As length of fat increases, there are more van derwaals forces acting on the molecule, so melting point

increases

Because saturated fats can stack neatly on top of each

other, a saturated fat has a higher melting point than

and unsaturated fat of the same length

H2 and a Nickel(Ni) or Platinum(Pt) catalyst can be

used to hydrogenate unsaturated fats, making them

solid at room temperature

Fats in General


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Objective B.4.4Compare the structures of the

two essential fatty acids, linoleic

(omega-6 fatty acid) andlinolenic (omega-3 fatty acid)

and state their importance.

By: Nadege Assassi


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Essential Fatty Acids Ingredients that the body needs to grow and develop healthily, but

cannot produce on its own Must enter the body through diet

Roles of EFAs

Hormone synthesis

Intercellular communication

Blood Clotting

Produce prostoglandins (maintain homeostasis)

Insulin Sensitivity

Lack of EFAs results in:

Heart Attack

Cancers

Insulin Resistance/Diabetes

Asthma

Schizophrenia/Alzheimers

Obesity Arthritis


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Linoleic Acid (Omega-6 Fatty Acid) C18H32O2

Omega: how many C from end lies the C=C bond Polyunsaturated carboxylic acid that cannot be produced by the

body

Has multiple C=C bond

18-Carbon chain

Colorless and liquid at room temperature Found in oils

2 cis double bonds

C-6 (hence, Omega-6) and C-9

Found in seeds and vegetable oils

Essential to skin cell repair and reduces body fat

Lack of Omega-6 Results:

Dry hair

Hair loss

Poor wound healing


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Linolenic Acid (Omega-3 Fatty Acid) C18H30O2

Polyunsaturated carboxylic acid that cannot be produced bythe body

Has multiple C=C bonds

18-Carbon chain

Also found in oils

3 cis double bonds C-3 (hence omega-3), C-6, and C-9

Found in thylakoid membranes of green leaves

Shown to be essential in thwarting cardiovascular problemsand lowering blood cholesterol

Prevents clotting and decreases inflammation Lack of Linolenic Acid Results in:

Vision and Nerve Problems Depression Poor Circulation

Arthritis


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Linolenic Acid

Linoleic Acid


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Objective B.4.5Define the term iodine numberand

calculate the number of C=C

double bonds in an unsaturated

fat-oil using addition reactions.


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Iodine Number

Iodine number: mass of I2 (in g) for particular reaction

I2 number used to identify number of unsaturated C=Cdouble bonds

Higher I2 number means more unsaturated bonds

I2 Number Calculation: I2 solution used in reaction is yellow brownish

Precise mass of solution added to 100g lipid solution

Solution becomes colorless

Mass of iodine required is iodine number Number of moles of I2 reacting with one mole of fat/oil

indicates number of double bonds present in fat/oil


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Iodine Number Worked Example

Linoleic acid has the formula C18H32O2. Determine theiodine number of linoleic acid.

Linoleic acid can also be written C17H31COOH.

A saturated fat formula is CnH

2n+1COOH. The difference

in C:H in linoleci is 2n-3: 4 less H atoms.

2Hs are lost for each double bond so 2 double bonds.

So 2 mol of I2 will react with 1 mol of the fatty acid (1 I2reacts with 1 double bond).

M of linoleic acid = 280 gmol-1 and M of I2 =254 gmol-1

So 280 g of lipid reacts with 508 g I2

So 100 g reacts with 508 x 100 / 280 = 181 g

Iodine number = 181


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Iodine Number now you try

1. Determine the mass of I2 that can add to 100 g linolenicacid.

1. A sample of fat containing 0.02 moles fatty acid wasfound to react with 10.16 g of iodine. Determine thenumber of carbon-carbon double bonds present in thefatty acid.


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Objective B.4.6Describe the condensation of

glycerol and three fatty acids

molecules to make a triglyceride.


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Fats

Two classes of molecules.

Saturated fatty acids.

No double bonds between carbons in molecule.

Hydrogen molecules saturate carbons in place ofdouble bonds.

Unsaturated fatty acids.

One to three double bonds between carbons per

molecule. Lower melting point.


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Triglycerides

Three fatty acids combinewith a glycerol backbone

to create a triglyceride. One bond forms at a time

by condensation betweenCOO- on the fatty acids

and theOH on theglycerol.

Glycerols IUPAC name is

propane-1,2,3-triol.


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Ester Linkage

Ester linkage bondbetween a hydroxyl and

carboxylic acid. A condensation reaction

occurs to combine thetwo molecules with the

loss of a water molecule. This type of condensation

is called esterification.

Result is a triglyceride.


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Hydration

The reverse reaction will require water and will producethe fatty acid and glycerol monomers.


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Objective B.4.7Describe the enzyme-catalysed

hydrolysis of triglycerides during

digestion.

By: Nidah Khakoo

Q i k f h


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Quick Refresher:

What are triglycerides?

Fats and oils are known as triglycerides

Formed from glycerol and fatty acids

Difference between fats and oils?

Fats contain saturated fatty acidgroups

NO C=C double bonds

Oils contain at least one C=C bond The C=C bonds give that kinked

shape.


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Hydrolysis of Fats

1. Triglyceride is hydrolyzed by lipases.

2. Glycerol and fatty acids are broken down to

produce CARBON DIOXIDE, WATER, andENERGY.

3. Fats are in a less oxidized form then

carbohydrates so weight for weight produce

MORE energy


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Hydrolysis of Fats

Naturally occurring fats and oils are also known as esters.

In an esterification reaction, there is an interaction of a

carboxylic acid and an alcohol, aided by a catalyst.

The REVERSE of an esterification reaction is known as

hydrolysis.

This is the addition of water to the ester link, breaking

apart the ester into monoglycerides and diglycerides.

Requires the presence of a catalyst.


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Objective B.4.8Explain the higher energy

value of fats as compared to

carbohydrates

By: Athina Krimitzi


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Gram for gram, fats provide more

energy than carbohydrates.

Fats require more oxidation to

become CO2 and H2O than docarbohydrates.

carbohydrates already have one oxygen for

every carbon atom

each carbon atom in a carbohydrate needsonly one more oxygen

every carbon atom in a fat molecule needs

two oxygens


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The oxidation of fats takes

longer, but it also gives off

more energy.

When you weigh acarbohydrate, more oxygen is

included in that weight. When

you weigh a fat, you get more

carbon atoms per gram and

therefore, gram for gram, the

fats will give even more energy

(over twice as much) than will

the carbohydrates.


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Carbohydrates

C6H12O6 + 6O26CO2 + 6H2O

CH2O + O2CO2 + H2O

Fats 83O2 + C58H112O658CO2 + 56H2O

Examples


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Objective B.4.9Describe the important roles oflipids in the body and thenegative effects that they can

have on health.

By: Nicole Romanzi


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LipidsImportant roles are:

Energy storage as triacylglycerols Insulation and protection of organs

Steriod hormones

Structural component of cellmembranes

Omega-3-poly unsaturated fatty acidsreduce the risk of heart disease

Poly-unsaturated fats may lower LDLcholesterol

Negative effects: Increased risk of heart disease fromincreased levels of LDL cholesterol andtrans fatty acids

Obesity


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Energy Storage and Insulation

Lipids break down slower thancarbohydrates

So they cant be used as fast energy

like glycogen can.

Lipids are more efficient energy stores,

and a good thermal insulator

Also protects organs from being

harmed when a person jumps or fallsor similar exercises


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Benefits of Fats Omega-3 poly-unsaturated

fatty acids

Proven to reduce the risk

of heart disease

Poly-unsaturated fats

May lower the levels of

LDL cholesterol


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Hormones and Membranes Some lipids are steroid hormones

i.e.: almost all steroids, most

notably estrogen, testosterone,

and adrenaline

All are able to pass through the

cell membrane and are fat-

soluble

Some are also precursors tosome vitamins, Like Vitamin D

Membranes Lipids are a large part of the

semi-permeable cell

membranes lipid bilayer. Most

of the structure of the bilayer is

made of lipids.


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NEGATIVE EFFECTS Increased risk of heart disease fromelevated levels of LDL cholesterol and

trans fatty acids

The major source of low-densitylipoproteins (LDLs) is saturated

fats i.e.: lauric acid (C12), myristic

acid (C14), and palmitic acid (C16)

Obesity

Lipids are fats. If a personconsumes too many fats withoutburning them off, they getoverweight and eventually obese.


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References

http://www.vaxa.com/linoleic-acid.cfm

http://ak47boyz90.files.wordpress.com/2009/07/picture

7.png?w=491&h=321

http://www.heart.org/HEARTORG/GettingHealthy/FatsA

ndOils/Fats101/Saturated-Fats_UCM_301110_Article.jsp

http://www.umass.edu/nibble/infofile/unsatfat.html

http://webcache.googleusercontent.com/search?q=cache:

WXGZeCkSZvEJ:dl.clackamas.edu/ch106-

06/hydrolys.htm+hydrolysis+of+fats&cd=1&hl=en&ct=cln

k&gl=us
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b4 lipids lidia, kate c, nadege, nidah, athina, nikki

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