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Phytochem > Lipids > Flashcards

Lipids Flashcards

1
Q

heterogenous group of compounds. They are compounds of long chain fatty acids and glycerol and higher monohydric alcohols.

A

Lipids

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2
Q

triglycerides (or currently referred to as triacylglycerols) because they are esters composed of three fatty acid units joined to glycerol, a trihydroxy alcohol.

A

Fats and oils

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3
Q

Functions of fats

A

They provide energy for living organisms, insulate body organs, and transport fat-soluble vitamins through the blood.

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4
Q

acylglycerols are solid generally if the fatty acids are saturated and liquid when unsaturated .

A

True

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5
Q

What do you do when both solid and liquid is present in an acylglycerol

A

both are present, cooling results in the deposition of the saturated portion e.g. stearin in cod liver oil.

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6
Q

all three OH groups on the glycerol molecule are esterified with the same fatty acid, the resulting ester is…..

A

simple triacylglycerol.

If they are different esterification it will be called “mixed triacglycerol”

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7
Q

The unsaturated acids is mostly linked to the secondary hydroxyl esp C18 olefinic acids

True/false

A

True

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8
Q

Triacylglycerides obtained from animals are fats, those obtained from plants are….?

A

Oils

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9
Q

What is the most abundant saturated fatty acid and what is the most abundant unsaturated

A

Palmitic avid - saturated

Oleic acid- unsaturated

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10
Q

May be applied to natural mixtures containing appreciable quantities of esters derived from higher monohydric alcohols of the methyl alcohol series combined with fatty acids.

A

Waxes

Egs. dodecyl alcohol , (C12H25OH), ceryl alcohol (C26H53OH) and myricyl alcohol (C30H61OH).

Sources
carnauba wax from plants and animal products include: spermaceti, beeswax and wool-fat.

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11
Q

What makes waxes different from fats

A

Waxes differ from fats by being saponified only by alcoholic alkali whereas fats are saponified by both aqueous and alcoholic alkali. Waxes also contain a considerable amount of free acids.

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12
Q

Esters of glycerophosphoric acids in which the 2 free hydroxyls of the glycerol are esterified with fatty acids and the 2 of the phosphoric acid is esterified to an alcohol (choline, serine glycerol etc

A

Lecithins

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13
Q

Where are lecithin found in animals

A

complex lipids in active tissues of the brain and liver.

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14
Q

Ways fats and oils are obtained from plants

A

American cotton seeds by delinting and castor or ground nut are decorticated .
•The oil may be obtained by cold or hot expression, centrifuging or solvent extraction. The crude oil may be refined for commercial use e.g. olive oil .

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15
Q

Why does castor oil require steaming in its extraction

A

inactivate lipase but also to detoxify toxin -ricin

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16
Q

acids which combine with glycerol in the naturally occurring fats and oils. These acids contain even number of carbon atoms linked together in long chains which are in general un-branched.

A

Fatty acids

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17
Q

Classification of fatty acids

A

a. Saturated fatty acids
•b. Unsaturated fatty acids
•c. Branched chain fatty acids, and
•d. Cyclic fatty acids.

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18
Q

What are saturated fatty acids and examples

A

contain only single bonds in their hydrocarbon chain.
•The general formula is:
–R — COOH

Most occurring fatty acids are palmitic(C16) and stratum acid (C18)

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19
Q

What characterizes unsaturated fatty acids

A

-one or more d-bonds

Cistrans isomer

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20
Q 
Oleic acid (C10), Ricinoleic (C18)
Linoleic acids
A

Examples of unsaturated fatty acids

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21
Q

Which type of unsaturated acid are considered beneficial to humans

A

Monounsaturated fatty acids

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22
Q

important dietary fats.
•They lower disease risk and found in foods such as: vegetable oils (such as olive, sunflower, soy, and corn), nuts, seeds, and fish

A

Omega-3, omega-6 and omega-9 fatty acids

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23
Q

What does the “omega 3 “ refer to

A

refers to the position of the final double bond which is three carbon atoms from the “omega” or tail end of the molecular chain.

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24
Q

Benefits of omega 3

A

Hearth health

Etc etc

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25
Q

What is the most common omega-6 fat

A

Linoleic acid which can be converted into longer omega-6 fats such as arachidonic acid (ARA).

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26
Q

an omega-6 fatty acid found in certain oils, such as evening primrose oil and borage oil.

A

Gamma linolenic acid (GLA)

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27
Q

What is the function of GLA

A

When consumed, it is converted to another fatty acid, dihomo-gamma-linolenic acid (DGLA). When used in a high dose as GLA supplements they reduced symptoms of rheumatoid arthritis.

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28
Q

Which Omega is monosaturated and which is poly saturated

A

Mono- Omega 9

Poly-omega 3

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29
Q

Example of Omega 9

A

Oleochemicals acid and most monosaturates

30
Q

Health benefits of Omega 9

A

high-monounsaturated fat diets could reduce plasma triglycerides by 19% and “bad” very-low-density-lipoprotein (VLDL) cholesterol by 22% in patients.
mlkm

31
Q

straight-chain polyunsaturated fatty acids (PUFAs) of 20 carbon units in length that have been metabolized or otherwise converted to oxygen-containing products.

A

Eicosanoids

32
Q

As chain length and degree of saturation of solvent increases, what happens to solubility of fats

A

It decreases

33
Q

Saturated and unsaturated which is solid at room temperature

A

Saturated fatty acids are solid at room temperature, while unsaturated fatty acids are liquid.

34
Q

What causes the yellow color of butter since fats and oils are colourless

A

The yellow colour of butter is due to carotene pigment; the taste of butter comes from two compounds—diacetyl and 3-hydroxy-2-butanone—produced by bacteria in the ripening cream from which the butter is made.

35
Q

What reduces the melting points of fatty acids

A

Short chain or unsaturation( since they are liquids)

36
Q

What increases viscosity and what decreases it

A

Increasing the degree of unsaturation, the viscosity decreases and when the length of the chain increases the fatty acids components also increases the viscosity.

37
Q

What increases refractive index

A

Increasing the degree of unsaturation and length of chain

38
Q

What happens when fats are treated with mineral acids, the alkalis or fat enzyme lipase or hydrolases

A

Hydrolysis which yields glycerol and fatty acid constituents

39
Q

Hydrolysis by alkalis, such as NaOH or KOH leads to the formation ….

A

sodium or potassium salts of fatty acids. The salts are known as soaps and process of its formation is saponification.

40
Q

Between KOH and NaOh what makes soap soft or hard

A

KOH makes soft soap while NaOH makes hard soap.

41
Q

What are rancid oils or fats

A

Oils and fats on long storage in contact with heat, light, air and moisture

42
Q

What chemical changes result in rancididty

A

i) Enzymatic hydrolysis,
•(ii) Air oxidation of unsaturated fatty acids, and
•(iii) β- oxidation of saturated fatty acids.
–Hydrolysis of fats is caused by enzyme lipase which is produced by microorganisms present

43
Q

What enzyme causes hydrolysis if fat to rancid

A

Lipase

44
Q

How can oils be converted into solid fats (glycerides of saturated fatty acids)

A

Oils containing unsaturated fatty acids can be hydrogenated in presence of high temperature, pressure and finely divided nickel.

45
Q

What happens when excess of hydrogen is passed through oils under pressure and in presence of copper-chromium catalyst

And what is hydrogenolysis

A

Oils and fats are converted into glycerol and a long chain aliphatic alcohol

The splitting of fat by hydrogen is known as hydrogenolysis.

46
Q

What happens when unsaturated fat is treated with halogens like iodine

A

they take up iodine or other halogens at their double bond site.

47
Q

What is iodine number of fats

A

Iodine number is the mass of iodine in gm that is consumed by 100 gm of the fat or wax. They are often used to determine the amount of unsaturation in fats, oils and waxes.

48
Q

What is acid value and formula

A

The acid value is the number of mg of potassium hydroxide required to neutralize the free acid in 1 g of the substance.
= acid x 5.61/ weight of substance

49
Q

Sap value formula

A

Sap value = (b-a)x factor of acidx 28.05/ weight

50
Q

What is sap value used to measure

A

measure of the average molecular weight (or chain length) of all the fatty acids present

51
Q

Why do long chain acids have low sap value to short chain

A

because they have a relatively fewer number of carboxylic functional groups per unit mass of the fat as compared to short chain fatty acids

52
Q

What is ester value

A

the difference between the saponification value and acid value gives the ester value:

53
Q

Why do micelles(oil droplets) repel each other

A

because of their charged surfaces and do not coalesce

54
Q

substances frequently found dissolved in fats and oils which cannot be saponified by the caustic alkalis but are soluble in the ordinary fat solvents and are extractable into ether.

A

Unsaponifiable matter

55
Q

Examples of unsaponifiable matter

A

higher aliphatic alcohols, sterols, pigments, and hydrocarbons.

56
Q

What is hydroxyl value

A

the number of milligrams of potassium hydroxide required to neutralize the acetic acid

measure of the content of free hydroxyl groups in a chemical substance,

57
Q

an oil that hardens to a tough, solid film on exposure to air. The oil hardens through a chemical reaction in which the components polymerize by the action of oxygen.

A

Drying oil

58
Q

What is the iodine number an oil should have before it becomes drying oil

A

> 130

59
Q

What are drying oils used for

A

They are a key component of oil paint and some varnishes. Some examples include: linseed oil, tung oil , walnut, poppy seedy

60
Q

What is a semi drying oil

A

A semi-drying oil is one which partially hardens when it is exposed to air. This oil has an iodine number of 115-130. Corn oil, Cottonseed oil, Sesame oil and Grape seed oil.

61
Q

Examples of non drying oil

A 
Almond
Cocoa butter
Coconut oil
Mineral oil
Olive oil
Peanut oil
62
Q

What is acrolein test

A

Aim:to detect fat or glycerol

Reagent: potassium bisulphate (KHSO4)

+ test: glycerol portion of the molecule is dehydrated to form an unsaturated aldehyde, acrolein that has a pungent irritating odour

63
Q

highly toxic fats that can cause insulin resistance, inflammation and significantly raise the risk of serious diseases like heart disease.

A

Trans fats

64
Q

It is formed transiently as intermediates in the biosynthesis of glycerophospholipids.

A

Diacylglycerols

65
Q

What is iodine value

High iodine value in unsaturated fats mean?

A

iodine adsorption value or iodine number or iodine index) is the mass of iodine in grams that is consumed by 100 grams of a chemical substance.

higher the iodine number, the more C=C bonds are present in the fat. Or high unsaturation

66
Q

Family if arachis oil and use

A

Leguminosae

laxative and given as an enema. May be used to adulterate other fixed oils e.g. olive oil

67
Q

Elaeis guineensis OG the family (Arecaceae).

A

Palm kernel oil

68
Q

What makes palm kernel different from palm oil

A

It differs chemically from palm oil in containing a high proportion (50%) of the triglycerides of lauric acid, a saturated, medium chain length fatty acid .

69
Q

What is Fractionated Palm Kernel Oil BP

A

palm oil which has undergone selective solvent fractionation and hydrogenation. It is a white, brittle solid, odourless or almost so, with m.p. 31–36°C making it suitable for use as a suppository base.

70
Q

Which oil has antibiotic resistant to Staph. aureus strains

A

Linseed oil

71
Q

Why is lalonin not a true fat

A

lanolin lacks glycerides (glycerol esters), it is not a true fat. Lanolin primarily consists of sterol esters.

Phytochem (9 decks)

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