Qualitative Reactions of Lipids Flashcards by Franchez Cassandra Escander

are biomolecules that are structurally poorer in oxygen but made up of carbon,
hydrogen and oxygen like carbohydrates.

lipids

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groups of structurally different molecules that
are amphipathic in nature of which the majority is hydrophobic, however each molecule contains a
polar region

lipids

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A molecule with both a polar and non-polar parts

amphiphatic

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strongly determines the structures these
molecules assume in nature.

what part of lipid

hydrophobic

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functions of lipids

structure
energy
energy storage
signaling (steroids and eicosanoids)

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The
bulk of the mass of lipid molecules in a mammalian system are those found structurally in

cellular membranes
triacyglycerides
cholesterol ethers

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are a major component of cellular membranes and can be divided into classes based on their
headgroup and further into species based on the acyl group composition

phospholipids

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Based on the structure of lipid’s backbone, they are divided into two groups;

complex lipids
simple lipids

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are esters of fatty acids.

complex lipids

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example of complex lipids

acylglycerides, phospholipids, sphingolipids and waxes, fatty acids

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complex lipids are e covalently joined via an
ester linkage to (3)

trihydroxy alcohol
glycerol
or its derivative

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s are the major component of most foods, typically making up more than 95 to 99% of
the total lipids present

trigylceride
triacylglycerols

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are mostly solid at room temperature and could raise the
level of bad cholesterol (Low density lipoprotein or LDL) which may pose potential health
consequences.

saturated lipids

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r, are either monounsaturated or polyunsaturated
which are both liquid at room temperature, but only the polyunsaturated lipids remain liquid even
when chilled

unsaturated lipids

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remain liquid even
when chilled

polyunsaturated lipids

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are considered most desirable as they help increase the good
cholesterol (High density lipoproteins or HDL) in our body

monounsaturated fats

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on the other
hand, could lower the overall cholesterol level, but they also reduce the good cholesterol (HDL).

polyunsaturated fats

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samples used (7)

olive oil
vegetable oil
canola oil
butter
milk
starch soln

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what are prepared before lab? (3)

10% Ethanol solution of KOH
0.4% of Bromine water
Sudan IV (0.1%)

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how is 10% ethanol solutio nof KOH prepared?

Weigh 10 g of KOH. Dissolve in 50 ml of ethanol and make the
volume to 100 ml.

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how is 0.4% bromine water prepared?

Measure 0.4 ml of bromine and add 99.6 ml of water

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how is Sudan IV (0.1%) prepared?

Weigh 100 mg of Sudan IV and dissolve in 100 ml of water

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Equipment used for paper spot test

Whatman no.1 Filter paper

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If the spot on the paper assumes a translucent appearance, that means the sample under
test is a ___

fat or oil

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positive on spot test is

spot on the paper

solubility test reagents (9)

water dilute acetic acid dilute KOH ethanol benzene ether acetone chloroform carbon tetrachloride

for water, which of the samples are insoluble?

all

for dilute acetic acid, which is soluble for the samples?

partially soluble for milk

for dilute KOH, which is soluble for the samples?

milk (partially soluble) and starch solution

for Ethanol, which samples are soluble?

Olive Oil (PS) Vegetable Oil (PS) Canola Oil (PS) Butter (PS) Milk (PS)

for Benzene, which samples are soluble?

OO VO CO B

for Ether, which samples are soluble?

OO VO CO B

for acetone, which samples are soluble

OO VO CO B M(PS)

for Chloroform, which is soluble?

OO VO CO B M (SS)

for Carbon tetrachloride, which samples are soluble

OO VO CO B

classification of lipids based on composition

simple lipids complex lipids derived lipids

examples of simple lipids

fats, waves

examples of complex lipids

phospholipids non-phosphorylated lipids lipoproteins sulfolipids

examples of derived lipids

isoprenoids fat-soluble vitamins steroids ketone bodies fatty acids

lipids based on function

storage structure signals, cofactor, and pigments

lipids for storage

fats, oils

lipids for structure

phospholipids non-phosphorylated lpids

lipids as signals, cofactor, and pigments

phosphatylinositol elcosanoids steroid hormones fat soluble vitamins

how many drops of sample on paper spot test

2 drops

when brought in contact with a substance like paper, penetrate through it, creating a transluscent spot

lipids

are lipids non-volatile?

yes

does not absorb enough heat to vaporize

spot of grease

when liquid is inside the sheet of paper, it diffracts light causing what phenomenon

translucent

how much solvent for the solubility test

5mL

how many drops of sample for solubility test

2-3 drops

Take ___ ml of distilled water, add a ____drops of emulsifier (bile salt) and the same amount of sample in a test tube.

5 mL 2-3 drops 2-3 drops sample

lipid is dispersed in a form of ___ i.e. fats

micelles

This is brought about as a result of the lowering of the surface tension between fat and water.

micelles

The bile salts or other substances that bring about emulsification are referred to as

emulsifiers

yellowish brown or green fluid produced in the liver and stored in gallbladder

bile

acts like soaps and other emulsifiers; they contain both polar and nonpolar region, helping to break fats in foods into smaller pieces, allowing them to be hydrolyzed more easily

bile salts

lowers the surface tension of oil with water

bile salts

this test involves mixing a lipid sample with water and an emulsifying agent (bile salt). If an emulsion form (a milk appearance), it is positive for the presence of lipids. This test specifically confirms that a sample lipid contains oil due to their ability to form emulsion when mixed with water.

emulsification test

– this test is a color reaction test that shows the presence of lipids. When a lipid sample is mixed with Sudan IV stain, a positive indication of red coloration appears. With the help of a microscope, oil droplets that are stained prove that the stain is very specific for lipids.

sudan IV test

This test is used to identify between saturated and unsaturated lipids. Unsaturated lipids react with bromine water having decolorization of bromine (due to presence of carbon-carbon double bonds).

bromine test

sudan IV test Take a few ml of ___water in a test tube and add a drop or two of the sample to it. Place a small drop of this emulsion on a micro slide and add to it a little bit ___ ___ stain, mix and put a cover glass

distilled Sudan IV

positives for sudan IV test

all except starch solution and milk

positives for emulsification test

all except starch solution (can but need bile salt)

. Take a few ml of ___ in a test tube and add a few drops of sample to it bromine test

ethanol

. To this add a few drops of ___% ___water drop by drop. bromine test

0.4 bromine

The intensity of the colour developed corresponds to the degree of

unsaturation

If the same test is performed with _______ no colour will be developed, as it is a saturated aci

aceticacid

Take ___ ml of chloroform in a test tube and dissolve a pinch of the sample in it Liebermann-Buchard test

2 mL

To this add at first ___ drops of ____ ____and then a drop or two of concentrated ___from the sides of the test tube.

8-10 drops acetic anhydride h2so4

which uses acetic anhydride and sulfuric acid as reagents, that gives a characteristic green color in the presence of cholesterol

Lieberman-Buchard test

This color is due to the –OH group of cholesterol and the unsaturation found in the adjacent fused ring.

green color

liebermann buchard test will be positive in what

butter

Refers to both true and fat-like substances. These are biomolecules that are insoluble in water but are soluble in organic solvents.

lipid

The ___ insolubility is due to the fact that the polar portion of their molecule is much smaller than the non-polar portion.

water

Important function of lipids is t the

storage of energy in form of body pfat

one of the building blocks of lipids,

fatty acids

which part of the lipid bilayer is hydrophilic

polar head

which part of lipid bilayer is hydrophobic

nonpolar tails

Helps us determine the presence or absence of lipid, depending upon the color change.

qualitative analysis of lipid

The qualitative analysis of lipid is an analytical method that detects lipids by the characteristic change in sample’s color.

qualitative analysis of lipid

lipid test

paper spot test solubility test emulsification test sudan IV test bromine test liebermann-buchard test

A preliminary test for the lipids, which is characterized by a translucent and greasy spot.

paper spot test

The ___ will not wet the filter paper, unlike water.

lipid

The lipids will form a ___ ue to their greasy texture, and penetrate the filter paper.

greasy/transparent spot

Confirms the presence of fats in the given sample.

paper spot test

* Like water, the lipids soak into the paper fibers, but the ___ spot evaporates much slowly than water

lipid

forces that hold the lipid molecules together are stronger/weaker than those in water molecules)

stronger

What property of lipids is detected by paper spot test?

Lipids are oily or greasy nonpolar molecules

It is the preliminary test that detects the presence of all lipids.

solubility

detects lipid solubility in various solvents to check whether it is miscible of immiscible in polar or non-polar solvents.

solubility test

Lipids are readily miscible in ___ solvents

non polar

is the property of two substances to completely mix to form a homogenous solution.

miscibility

s the property of two substances that do not completely mix to form solution.

immiscibility

VO solubility test on water methylene chloride ether toluene

water - methylene chloride + ether + toluene +

lecithin test on solublity water methylene chloride ether toluene

w - slightly mixed mc - + e + toluene +

test is used to detect the presence of lipid in a solution. The principle of lipid binding and solubility in non-polar compounds underpins this test.

Sudan IV test

is used to detect the presence of lipids. It is a procedure that uses emulsifying agents to stabilize a water-oil emulsion.

emuslification trest

mulsify lipids, causing them to appear as tiny droplets suspended in the solution.

emulsifying agents

It is a qualitative test used to detect the unsaturated fatty acids or double bond in a lipid sample.

bromine water test

are found in the structure of unsaturated fatty acids

double bonds

If no change in color---it is a __ bromine test

saturated lipid

If it becomes colorless--- it is ___ lipid bromine test

unsaturated

To detect the presence of cholesterol.

liebermann buchard test

reacts with the strong concentrated acid, i.e. sulphuric acid and acetic anhydride.

cholesterol

act as a dehydrating and oxidizing agent in Liebermann Buchard test

Sulfuric acid acetic anhydride

indicates cholesterol in a sample by giving bluish-green colour to the solution. what result

positive test

It is a chemical test used to the presence of amino acids, peptides, and proteins

ninhydrin test

This test involves the addition of ninhydrin reagent to the test sample that results in the formation of deep blue color, often termed as Ruhemann’s purple.

ninhydrin test

deep blue color formation in ninhydrin test

Ruhemann's purple

: ___ and ___reaction products positively identify free amino groups on amino acids and proteins.

blue purple yellow