LIPIDS Flashcards
Collective term for fixed oil, fats and waxes.
LIPIDS
are biomolecules that are insoluble in water but readily soluble in organic solvents, such as chloroform or acetone
LIPIDS
lipids are classified by their ____
miscibility/immiscibility in water
lipids do not have any common ____
building blocks
Lipids are not defined by a particular functional group, thus they have a ____ of structures and functions.
variety
Lipids contain many ____ C—C and C—H bonds and few polar bonds resulting in their water insolubility.
nonpolar
Are heterogeneous group of compounds (fats, oils, steroids, waxes and related compounds), that are related more by their physical than by their chemical properties.
Lipids
Properties of Lipids
____ to touch, leaves a permanent oily stain on paper;
greasy
Properties of Lipids
____ than water
lighter
Properties of Lipids
When ____, colorless with bland odor and taste;
pure
Properties of Lipids
____ color in fat is due to carotene
yellow
Properties of Lipids
Yellow color in fat is due to
carotene
provitamin A
Properties of Lipids
When ____ strongly, undergoes decomposition forming acrid flammable vapors
heated
Properties of Lipids
whenignited, they burn with a ____ flame.
sooty
- test conducted for lipids
- leaves a permament oily stain on paper
grease spot test
acrid flammable vapors is called
acrolein (propenal)
egg yolk contains, an emulsifying agent
lecitin
lipid soluble vitamins
A D E K
Major Roles of Biological Lipids
They serve as ____ of biological membranes.
structural components
Major Roles of Biological Lipids
They provide energy reserves, predominantly in the form of ____.
triacylglycerols
Major Roles of Biological Lipids
Both lipids and lipid derivatives serve as ____.
chemical messengers
Major Roles of Biological Lipids
____ aid in lipid solubilization.
lipophilic bile acids
Biomedical Importance
Fats are stored in ____
adipose tissue
Biomedical Importance
Fat stored in adipose tissue serves as ____ in the subcutaneous tissues and around certain organs
thermal insulator
Biomedical Importance
Nonpolar lipids act as ____, allowing rapid propagation of depolarization waves along myelinated nerves;
electrical insulator
Biomedical Importance
Lipoproteins occur in both ____ and ____, and also serve to transport lipid in the blood.
cell membrane & mitochondria
Biomedical Importance
stored in adipose tissue serves as thermal insulator in the subcutaneous tissues and around certain organs;
fats
Biomedical Importance
act as electrical insulator, allowing rapid propagation of depolarization waves along myelinated nerves;
nonpolar lipids
Biomedical Importance
occur in both cell membrane and mitochondria, and also serve to transport lipid in the blood.
lipoproteins
- Important dietary constituents
- High energy value
- Contains fat-soluble vitamins and essential fatty acids
lipids
- Are necessary fats that humans cannot synthesize, and must be obtained through diet.
- Are long-chain polyunsaturated fatty acids derived from linolenic, linoleic, and oleic acids.
essential fatty acids
Classification of Based on the “alcohol component”
Ester of fatty acid and low MW monohydric alcohol
simple lipid
Classification of Based on the “alcohol component”
- esters of three molecules of fatty acids plus one molecule of glycerol.
- Found in adipose tissue, butterfat, lard, suet, fish oils, olive oil, corn oil
triglycerides
Classification of Based on the “alcohol component”
ester of fatty acid and glycerol
fats/fixed oil
Classification of Based on the “alcohol component”
ester of fatty acid and high MW polyhydric alcohol
waxes
Classification of Based on the “alcohol component”
butterfat, lard, suet, fish oils, olive oil, corn oil
triglycerides
Classification of Based on the “alcohol component”
beeswax, head oil of sperm whale, cerumen, carnauba oil, and lanolin
waxes
the only vegetable oil that is solid at room temp
cocoa butter
____ can be converted into smaller molecules by hydrolysis
hydrolyzable lipids
- cannot be cleaved into smaller molecules by aqueous hydrolysis
- resistant to hydrolysis
Nonhydrolyzable lipids
head oil of sperm whale contains
spermaciti
expensive oil coming from the sperm whale
ambergris
Hydrolyzable lipids are derived from
fatty acids
Fatty acids are ____ with long C chains of 4-36 (even number) C atoms.
carboxylic acids (RCOOH)
Naturally occurring fatty acids have an ____ number of C atoms.
even
have no double bonds in their long hydrocarbon chains.
saturated fatty acids
have 1 or more double bonds (generally cis) in their long hydrocarbon chains.
unsaturated fatty acids
As the number of double bonds in the fatty acid increases, the melting point ____.
decreases
nomenclature used in unsaturated fatty acids
omega nomenclature
can act as hormones
prostaglandins
melting point of stearic acid
71C
melting point of oleic acid
16C
chemical formula of saturated fatty acids
CnH2nO2
chemical formula of unsaturated fatty acids
CnH2n - (2 no. of db) O2
unsaturated fatty acids with 1 double bond
monounsaturated
unsaturated fatty acids with more than 1 double bond
polyunsaturated
simplified nomenclature
chain length : double bonds
NOMENCLATURE
carboxyl (COOH) carbon will be labeled as
C1
NOMENCLATURE
suffix - unsaturated
enoic acid
NOMENCLATURE
the terminal CH3 is called
omega carbon
Humans require which fatty acid
essential fatty acid
omega-3 linolenic acid
Precursor in the synthesis of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)
omega-3
linolenic acid
PHYSICAL and PHYSIOLOGIC PROPERTIES OF FATTY ACIDS
____ of even numbered carbon fatty acids:
* increases with chain length
* decreases according to unsaturation
melting point
PHYSICAL and PHYSIOLOGIC PROPERTIES OF FATTY ACIDS
containing three saturated fatty acids of 12 C or more is solid at body temperature
▫ 18:2 fatty residues are liquid at body temperature to below 0°C
triacylglycerol
PHYSICAL and PHYSIOLOGIC PROPERTIES OF FATTY ACIDS
must be fluid at all environmental conditions
▫ More unsaturated than storage lipids
membrane lipids
- Derived from eicosa- (20 carbon) polyenoic fatty acids
- Arachidonic acid is the major precursors
eicosanoids
- Are part of a family of biologically active lipids derived from the** twenty-carbon** essential fatty acids or eicosanoids;
- Relates to the products of the cyclooxygenase pathway
- Prostanoic acid as the central structural element
-
Three main groups
▫ Prostaglandins (PGs)
▫ Prostacyclins (PGIs)
▫ Thromboxanes (TXs)
prostanoids
central structural element of prostanoids
prostanoic acid
- behave like lipids but acts as local hormones
- Synthesized from eicosanoic polyunsaturated fatty acids (arachidonic acid) to form cyclopentane ring
- PG1, PG2, and PG3– numbers are based on the double bonds in the side chain
- The letter component identifies the functional groups of the cyclopentane ring
prostaglandins
prostaglandin with keto group in 9th position
PGE
prostaglandin with hydroxyl group in 9th position
PGF
- Cyclopentane ring interrupted with an oxygen atom;
- Its role is in clot formation (thrombosis)
thromboxanes
two major thromboxanes
A2 & B2
- Formed via the lipooxygenase pathway
- Has three (leukotrienes) to four (lipoxins) conjugated double bonds
LEUKOTRIENES & LIPOXINS
a proinflammatory agents and causes bronchoconstriction, thus play a part in asthma
leukotrienes
are esters formed from a fatty acid and a high molecular weight alcohol.
waxes
scientific name of sperm whale
physeter macrocephalus
major component of spermaceti wax
cetyl palmitate
synthetic form of cetyl palmitate
cetyl ester wax
Because of their long nonpolar C chains, waxes are very ____
hydrophobic