1. Types of lipids + FA Flashcards
1
Q
Lipids are characterized by their _______ sensation and ___________ properties when isolated
A
fatty sensation and lubricant properties
2
Q
solubility of lipids vs insolubility of lipids
A
- soluble in nonpolar organic solvents (hexane, chloroform, ether)
- insoluble in water
3
Q
3 major classes of lipids + what?
A
- simple lipids: FA esterified to alcohol
- compound lipids: conjugated to non-lipid moiety
- derived lipids: derived in living systems from simple or compound lipids
4
Q
structure of glycerol
A
3 carbon chain with OH on each carbon + H to fill all 4 of carbon’s bonds
5
Q
Triacylglyceride structure + type of bond?
A
3 FA esterified to glycerol
- ester linkage
6
Q
Are the R groups of FA in triacylglycerol the same?
A
no. short of long chain with carboxyl group at one end
7
Q
triglycerides account for ___% of extractable lipid material present in biological systems
A
90%
8
Q
difference between oil and fat?
A
- oil: liquid at room temp
- fat: solid at room temp
9
Q
Melting point: pure TG vs fats/lipids
A
- pure TG: sharp melting point
- fats: solid fat content decreases over a broad temperature range –> reflects mixture of TG
10
Q
short or long FA chain will melt faster?
A
short chain
11
Q
what are waxes?
A
FA esterified to a fatty alcohol (long chain alcohol)
12
Q
example of liquid and solid wax
A
- liquid: jojoba oil
- solid: beeswax
13
Q
Biosynthesis of wax: 2 steps + enzymes
A
- FA bound to Coenzyme A –> FA reductase catalyzes reduction of FA to fatty alcohol (carboxylic acid to alcohol)
- Fatty alcohol + FA bound to CoA (different than first one) –> Wax synthase –> makes wax ester
14
Q
waxes have limited application for food use –> 2 examples
A
- sealing agents (cheese)
- polishing agents (apples)
15
Q
Jojoba oil –> what? found where? used in what? + also considered as a potential _________ (because not __________ readily) food ingredient giving a __________
A
- liquid wax
- obtained from seeds of desert shrub native to southwestern US and norther Mexico
- cosmetics
- low calorie (bc not digested readily)
- fatty sensation
16
Q
True wax vs other compounds in wax category (examples)
A
true wax: FA esterified to a simple fatty alcohol
- other wax category: FA esterified to complex alcohols –> cholesterol and retinol
17
Q
Cholesterol and retinol –> present in what degree of quantity?
+ important bc they are ?
A
- mg and micrograms
- bc they are biologically active
18
Q
Cholesterol structure? vs cholesteryl ester (wax)
A
OH + 4 rings ish + alkyl chain
vs wax: R-C(double bond O)-O-4 rings ish + alkyl chain
19
Q
retinol structure? vs vitamin A ester (wax) structure
A
Retinol: hexane ish + alkyl chain with conjugated double bonds + OH
wax: hexane ish + alkyl chain + CH2O-C(double bond O)-R
20
Q
what are compound lipids?
A
A category of lipids made up of a simple lipid (generally TG) conjugated to a non-lipid molecule
21
Q
Compound lipids usually separated into 3 categories:
A
- Phospholipids
- Glycolipids/sphingolipids
- Lipoproteins
22
Q
What are phospholipids?
A
TG with one of FA replaced with phosphoric acid or phosphoric acid derivative
23
Q
When the non-lipid moiety is a phosphoric acid instead, the phospholipid is called ?
Structure?
A
phosphatidic acid
Glycerol + 2 FA + O-P(double bonded O)(-O minus)-OH
24
Q
Structure of
- phosphatidylethanolamine
- phosphatidylcholine
- phosphatidylserine
- phosphatidylinositol
A
Glycerol + 2 FA + O-P(double bonded O)(-O minus)-X
- ethanolamine: X = O-CH2-CH2-NH2
- choline: X = O-CH2-CH2-N+(CH2)3 –> emulsifier!
- serine: X = O-CH2-CH(NH2)-COOH
- inositol: hexane with OH on each carbone
25
Which type of phospholipid is lecithin? cephalin?
- lecithin: Phosphatidylcholine
- cephalin: ethanolamine
26
What is particular of phosphatidylinositols? (3)
- non-nitrogenous groups attached to phosphatidic acid
- cell membrane
- not useful for food commodity
27
Phospholipids comprise ____% of lipid material found in food systems
<5%
28
Phospholipids have excellent _____A____ properties bc have both ________ and _______ groups
- common source of commercial A?
A: emulsifying
- hydrophobic and hydrophilic
- soybean oil
29
Glyco and sphingolipids are associated with _________________ in both plants and animals
membrane lipids
30
Glyco and sphingolipids = important class of lipids for food scientist?
No! although very important biochemically
31
Which type of lipids have a structure that is rarely known?
protein-lipid complexes (lipoproteins)
32
Function of lipoproteins?
circulate in blood to carry lipids to tissues for metabolism or storage (+ vice versa)
33
2 types of lipoproteins? + important in relation to which disease?
- High density lipoproteins and low density lipoprotein
- heart disease
34
Lipoproteins typically found in high levels in what food?
eggs
35
HDL vs LDL:
- good or bad?
- accounts for what fraction of all blood circulating cholesterol
- function
- higher levels = ?
HDL:
- good
- 1/3
- protective mechanism from dev. of heart disease by carrying away cholesterol from vessel walls and plaque to liver for disposal
- reduce risk of heart attack
LDL:
- bad
- N/A
- transports substances vital to cell function and development
- can accumulate in blood vessel walls --> blocks arteries + unstable plaque build-up = prone to rupture and formation of blood clots --> levels of LDL related to risk of heart attack and stroke
36
what are derived lipids?
+ 3 examples
- constituents derived from simple or compound lipid categories and that still retain their hydrophobic character
- FA, fatty alcohols, hydrocarbons and oxygenated derivatives thereof
37
Are derived lipids found in food systems?
Yes! and can play major roles in terms of functionality
38
Describe derived lipids fatty acids
Short to long chain aliphatic hydrocarbons with carboxyl group at one end
39
short chain FA (important as ________ compounds (______ or _____) + released by ________ + examples) vs longer-chain free fatty acid (flavour? + > C ___?)
- hint: give flavour? why or why not? at low of high concentration?
Short chain:
- important as flavour compounds
- can be released by lipolysis and can contribute to good (low concentration) or bad flavour (high concentration)
- ex.: butyric acid (C4), caproic acid (C6), caprylic acid (C8) (cheese/rancid flavour)
Longer chain:
- no flavour per se (bc no receptors on tongue) but gives soapy flavour in presence of mineral salts
- > C12
40
Presence of FFA can _______ the smoke point of edible oils when used for ________
lower, frying
41
Fatty alcohols made of (2)
- short or long chain = major contributor to flavour?
- more complex derived alcohols are often _____________ (ex.: ?)
higher alcohols (>C6) and sterols CH3-(CH2)n-CH2-OH
- short
- biologically active --> cholesterol
42
Examples of hydrocarbons and oxygenated derivatives thereof (4)
- short and long chain aliphatic hydrocarbons
- carotenoids
- xanthophylls
- terpenes
43
straight chain saturated hydrocarbons vs diverse unsaturated hydrocarbons
- in terms of flavour/reaction
- straight-chain --> of little note from flavour or reaction viewpoint
- diverse --> more of interest --> specifically terpenes build from isoprene units
44
How many carbons in isoprene units?
5 carbon
45
Terpenes build from what units?
- found in what? what properties?
- what are main constituents of essential oils? (2 types of terpenes)
- isoprene units
- found in fragrant oils obtained from leaves, flowers and fruits --> antimicrobial properties
- monoterpenes and sesquiterpenes
46
Number of isoprene units?
- Monoterpene
- sesquiterpenes
- diterpenes
- sesterterpenes
- triterpenes
- Monoterpene: 2
- sesquiterpenes: 3
- diterpenes: 4
- sesterterpenes: 5
- triterpenes: 6
47
_________ is the analytical property used as the basis for lipids' facile separation from _________ and carbs
- water insolubility
- proteins and carbs
48
primarily ________ are deposited in some animal tissues and organs of some plants
Triglycerides
49
lipid content in storage tissues can rise to ____-____% or higher
- what natural source has higher? how much?
15-20%
- soybean--> 40% lipid
50
nutritive and physiological important of lipids based on (2)
- role as fuel molecules (9kcal/g or 37 kJ/g for TG)
- source of essential fatty acids and vitamins
51
Lipid properties that are indispensable in food handling: pleasant _______ or _______ mouthfeel and ability to ________ many taste and aroma constituents of food
- oily or creamy
- solubilize
52
Bulk of lipid components in food systems are (2) + % of each
- fats and oils from simple lipid class --> 95-96%
- phospholipid from compound lipid class --> 4-5%
53
The composition and distribution of the (__________) _____ ____ on the ___________ backbone are major contributor to the overall properties of fats and oils extracted from biological systems
esterified fatty acid makeup + glycerol backbone
54
Are fatty acids generally found in their free form in living biological systems?
no! they are largely combined in the form of TG
55
How to make TG? in the lab (reaction formula)
1 glycerol + 3 FA + sodium hydroxide (catalyst) --> TG + 3 H2O
56
When counting carbons for a FA attached to the glycerol, which C is the first one?
the carbon double bonded to an oxygen
57
Saturated FA found in nature tend to be ______-numbered due to the mechanism of __________
vs sat FA with ______-numbered carbon --> found in very ____ amounts --> 2 examples
even-numbered
biosynthesis
- odd-numbered
- low
- pentadecanoic acid (15C) in milk --> around 1% of milk fat)
- heptadecanoic acid (17C) --> also in milk and plant oils --> around 0.6% of fat
58
are short or long chained saturated FA liquid vs solid at room temp?
short = liquid
long = solid
59
why does solubility of FA in water decrease with increasing chain length?
because increase of hydrophobicity
60
______ form of FA (_____) is water soluble and has strong surface tension-reducing properties
salt form of FA (soap)
61
how many carbons? + Systematic name
butyric acid
palmitic acid
stearic acid
butyric acid: C4: butanoic acid
palmitic acid: C16: hexadecanoic acid
stearic acid: C18: octadecanoic acid
62
how many carbons? + Systematic name
caproic acid
lauric acid
arachidic acid
caproid acid C6: hexanoic acid
lauric acid: C12: dodecanoic acid
arachidic acid: C20: eicosanoic acid
63
how many carbons? + Systematic name
- myristic acid
- capric acid
- caprylic acid
- myristic acid: C14: tetradecanoic acid
- capric acid: C10: decanoic acid
- caprylic acid: C8: octanoic acid
64
increase number of carbon = _______ melting point --> linear?
increase
- not linear!
65
unsaturated FA have ______ melting points than sat. counterpart at same chain length
lower melting points
66
Unsat FA are more or less reactive than sat? Why/what?
more reactive!
pentadiene system are highly reactive! --> where oxidation begins
67
3 most common unsaturated fatty acids? which are more common than the other one?
- oleic acid --> 18:1 (9) --> 34%
- linoleic acid --> 18:2 (9,12) --> 34%
- linolenic acid --> 18:3 (9, 12, 15) --> 5%
68
oleic acid vs elaidic acid
- both 18 carbon + 1 double bond
- oleic: cis
- elaidic: trans
69
Cis or trans has lower melting point?
cis has lower melting point --> packs less tightly
vs trans (margarine): high melting point
70
conversion of cis to trans has major effect on ______________ + on its _________ in the human body
melting point + metabolism in human body
71
what can also affect physical properties of monounsat fat besides cis/trans configuration?
positional isomerism
72
systematic name for C18:3 (9,12,15)
octadeca 9,12,15-trienoic acid
73
IUPAC naming vs biochemical nomenclature --> start counting double bonds from which end?
- IUPAC: from carboxylic end
- biochemical: from CH3 end (omega carbon)
74
omega nomenclature based on the assumption that all natural FA are in _____ form and double bonds are always ___________
cis form
unconjugated
75
C(??): (?) + omega (?)
- eicosapentaenoic acid
- docosahexaenoic acid
- arachidonic acid
- eicosapentaenoic acid--> C20:5 omega-3
- docosahexaenoic acid --> C22:6 omega 3
- arachidonic acid --> C20:4 omega 6
76
3 family groups exist for omega families? what type?
- with exceptions: these are part of which families:
- erucic acid (20:1) in mustard family of seeds
- arachidonic acid (20:4)
- C20-C22 FA with 5-6 double bonds in fish lipids
- omega 3 (linolenic type)
- omega 6 (linoleic type)
- omega 9 (oleic type)
- erucic acid --> omega 9
- arachidonic acid --> omega 6
- C20-C22 FA with 5-6 double bond --> omega 3
77
Natural state of most FA = __________ double bonds (separated by a __________ group)
unconjugated
- by a methylene group
78
thermodynamically speaking, is conjugated or unconjugated form more stable? which is more susceptible to autoxidation?
- conjugated form more stable
- conjugated is more susceptible to autoxidation
79
linolenic acid = relatively reactive and unstable and is readily converted into a __________ (what?)
- mixed bonding system
- having conjugated/unconjugated elements
80
Formation of active methylene group --> positioned where?
between conjugated and unconjugated double bonds
81
Conjugated linoleic acid (CLA) found in (2) are of special interest bc attributed to have an _______ effect
- most common = cis__ and trans__ isomer
- found in milk and meat
- anticarcinogenic effect
- cis9 and trans11
82
Why does 18:1 (2) and 18:1 (9) have such different melting points (51°C vs 13.4°C respectively)?
because the degree of the bend form by the double bond will modify the melting point!
- bigger the bend/angle, smaller the melting point will be
83
Crystalline lattice of FA stabilized by (?) along the acyl residues
hydrophobic interactions
84
Which FA can't be packed into crystalline lattice?
- unsaturated
- odd-numbered
85
Melting point of FA decreases with an increasing number of ____________ ___-double bonds
isolated cis-double bonds
86
4 types of less common FA
- branched chain FA --> have a hydrocarbon branch in the chain
- Hydroxy acids --> contain hydroxyl group in FA, present in oil of castor bean trees
- Cyclic FA --> contain a cyclic group in chain
- Acetylenic FA --> contain triple bond --> useful as antifungal
87
Malvalic acid = rare FA --> which category of less common FA?
- found in what?
- contains what?
- causes what? (2)
- branched chain FA
- found in cottonseed oil (1-3%)
- contains cyclopropene ring
- causes egg color problem in chicken eggs + pasty and rubbery yolks
88
Ricinoleic acid --> which category of less common FA?
- makes about ___% of FA in _______ oil
- can serve as an indicator for presence of this oil in ________ oil
- very ________ side chain = useful in industrial processes
- hydroxy FA
- 80% in castor oil
- edible oil
- very reactive side chain
