Module 2 Flashcards
are lipids homogenous or heterogenous?
heterogenous
what are the common building blocks of lipids?
they do not have any common building blocks
where do lipids occur frequently in?
nature
where can we find lipids in mammalian cell walls?
cholesterols
where can we find lipids in fungal cell walls?
ergosterol
in terms of chemistry, lipids are…
a mixed bag of compounds that share some properties based on the structural similarities, mainly a preponderance (abundance) of non-polar groups.
two main groups of lipids
hydrolysable lipids and fused-ring compounds
collective term for fixed oil, fats, and waxes
lipids
where are lipids soluble and insoluble in?
soluble in organic (non-polar) solvents and insoluble in water
due to the fact that lipids are not defined by a particular functional group…
they have a variety of structures and functions
why are lipids insoluble in water?
they contain many nonpolar C —– C and C —– H bonds and few polar bonds resulting in their water insolubility
what properties are lipids more related to each other?
physical properties
to the touch, lipids are…
greasy
lipids leave a
permanent oily stain on paper (Grease Spot Test)
which is lighter, lipids or water?
lipids
when pure, this is the color and taste of lipids
colorless and bland
causes the yellow color in fat
carotene (provitamin A)
what happens when lipids are heated strongly?
they undergo decomposition
what sort of vapors and flames do lipids produce once they are heated strongly?
acrid flammable vapors and they burn with a sooty flame
acrid flammable vapors from lipids can lead to
acrolein (propenal)
how do lipids serve within biological membranes?
as structural components (cholesterol)
lipids provide energy reserves, but in what predominant form?
triacylglycerols
both lipid and lipid derivatives serve as…
chemical messengers
aids in lipid solubilization
lipophilic bile acids
stored in adipose tissue
fat
what does fat serve as and where does it serve exactly?
as thermal insulator in the subcutaneous tissues and around certain organs (protection)
act as electrical insulators
nonpolar lipids
what does the act of electric insulation within nonpolar lipids allow?
they allow rapid propagation of depolarization waves along myelinated nerves
occur in both cell membrane and mitochondria
lipoproteins
what do lipoproteins do within our blood?
transport lipids
how are lipids important dietary constituents?
they have high energy value, contain fat soluble vitamins, and essential fatty acids
necessary fats that humans cannot synthesize and must be obtained through diets
essential fatty acids
what are essential fatty acids exactly?
long chain polyunsaturated acids
where are essential fatty acids derived from?
linolenic, linoleic, and oleic acids
in the classification of lipids based on alcohol component, lipids are…
esters
simple lipid; ester of fatty acid and
LMW monohydric alcohols
simple lipids are usually ___ at room temperature
liquid
most simple lipids are liquid in room temperature, except for…
solid vegetable oil (cocoa butter). solid in room temperature, and excellent as suppositories since they melt in human temperatures
fats/fixed oil; ester of fatty acid and
glycerol
fats/fixed oils are usually solid/semisiolids except for…
liquid animal fat (cod liver oil) which are excellent sources in oleo vitamins A and D
esters of three molecules of fatty acids plus one molecule of glycerol
triglycerides
where are triglycerides commonly found?
in adipose tissue, butterfat, lard, suet, fish oils, olive oil, corn oil
waxes; ester of fatty acids and
HMW polyhydric alcohol
examples of waxes
beeswax, (spermacetti) head oil of sperm whale and sperm whale vomit (ambergris), cerumen, carnauba oil, and lanolin
lipids that can be converted into smaller molecules by hydrolysis
hydrolyzable lipids
examples of hydrolyzable lipids
waxes, triacylglycerols, and phospholipids
cannot be cleaved into smaller molecules by aqueous hydrolysis
nonhydrolyzable lipids
examples of nonhydrolyzable lipds
steroids, fat-soluble vitamins, and eicosanoids
hydrolyzable lipids are derived from
fatty acids
fatty acids are…
long chained monocarboxylic acids (RCOOH) with C chains of 4-36 atoms
example of fatty acids
CH2(CH2)14COOH (palmitic acid)
naturally occurring fatty acids have an
even number of C atoms
have no double bonds in their long hydrocarbon chains. formula, suffix
saturated fatty acids
have 1 or more double bond (generally cis) in their long hydrocarbon chain. formula suffix
unsaturated fatty acids
formula for saturated fatty acids
CH3(CH2)nCOOH
formula for unsaturated fatty acids
CH3 (CH2-2#db)nCOOH
as the number of double bonds in the fatty acid increases,
the melting point decreases
simplified nomenclature of fatty acids
chain length:double bonds
carboxyl carbon of fatty acids
C1
specifies the lower-numbered C in the double bonds and helps find the position of any double bond
𐤃n
alternative nomenclature applied in human nutrition
omega-n nomenclature
named for linolenic acid because of the position of the first C-C in the nonpolar chain
omega-3 acid
fatty acid that humans require
omega-3 linolenic acid
fatty acids are precursors in the synthesis of
eicosapentaenoic acid (EPA) nad docosahexaenoic acid (DHA)
melting point of even numbered carbon fatty acids
increases with chain length and decreases according to unsaturation
contains three saturated fatty acids of 12 C or more and is solid at body temperature to below 0 C
triacylglycerol
18:2 fatty residues are…
liquid at body temperature to below 0 C
must be fluid at all environmental conditions
membrane lipids
which are more unsaturated: storage lipids or membrane lipids?
membrane lipids
(monoethenoid, monoenoic) acids containing double bond
monounsaturated
(polyethenoid, polyenoic) acids containing two or more double bonds
polyunsaturated
derived from eicosa- (20 carbon) polyenoic fatty acids
eicosanoids
eicosanoids are major precursors of
arachidonic acid
examples of eicosanoids are
prostanoids, leukotrienes (LTs), lipoxins (LXs)
part of a family of biologically active lipids derived from the twenty-carbon essential fatty acids or eicosanoids
prostanoids
prostanoids relates to the products of the…
cyclooxygenase pathway (COX)
central structural element of prostanoids
prostanoic acid
three main groups of prostanoids
prostaglandins (PGs), prostacyclins (PGIs), thromboxanes (TXs)
behave as lipids but mainly act as local hormones
prostaglandins
where are prostaglandins synthesized from in order to cyclopentane ring?
eicosanoic polyunsaturated fatty acids (arachidonic acid)
numbers are based on the double bond in the side chain of a prostaglandin
PG1, PG2, and PG3
what does the letter component identifies in the nomenclature of prostaglandins?
the functional groups of the cyclopentane ring
prostaglandins with a PGE component have which functional group within its cyclopentane ring?
keto group in 9 position
prostaglandins with a PGF component have which functional group within its cyclopentane ring?
hydroxyl group in 9 position
(review) keto functional groups have what formula?
R-(C=O)-R
cyclopentane ring interrupted with an oxygen atom
thromboxanes
two major thromboxanes?
thromboxane A2 and thromboxane B2
what role does thromboxane have?
clot formation (thrombosis) and is inhibited by blood thinners
what inhibits thromboxanes (and thrombosis in general)
blood thinners and anti thrombotics (clopidogrel, aspirin)
how are leukotrienes and lipoxins formed?
via the lipooxygenase pathway (LOX)
how many conjugated double bonds do leukotrienes and lipoxins have respectively?
three leukotrienes and four lipoxins
a proinflammatory agent and causes bronchoconstriction, and thus plays a part in asthma
leukotrienes
common leukotriene inhibitors
zyflo (zleuton), accolate (zarfirlukast), singulair (montelukast)
(LTIs) zyflo
zileuton
(LTIs) accolate
zarfirlukast
(LTIs) singulair
montelukast
esters formed from a fatty acid and a high molecular weight alcohol
waxes
general structure of waxes
R-(C=O)-OR
isolated from the heads of sperm whales
spermaceti wax
scientific name of spermaceti wax
physeter macrophalus
major component found in the head oil of sperm whales
cetyl palmitate
synthetic version of spermaceti wax and can be used in cold cream or petrolatum rose ointment
cetyl ester wax
what can waxes form on bird’s feathers, cheep’s wool, and make up beeswax (yellow wax)
protective coatings
what will happen to beeswax once you bleach it?
it turns into white wax
scientific name of beeswax
myricyl palmitate
like other esters, waxes are hydrolyzed with water in the presence of an acid or base to…
re-form the carboxylic acid and alcohol they came from (hence the term hydrolyzable lipids)
three esters formed from glycerol and three molecules of fatty acids. they are also the main storage forms of fatty acids
triacylglycerols (triglycerides)
triacylglycerols that have three identical fatty acid side chains
simple triacylglycerols
examples of simple triaclyglycerols
tristearin
triacylglycerols that have two or three different fatty acids
mixed triacylglycerols
examples of mixed triacylglycerols
oleopalmitostearin
contain only saturated fatty acids, make up most animal fat, and are solids at room temperature
saturated triacylglycerols
do saturated triacylglycerols contain double bonds?
no
contain at least one unsaturated fatty acid, make up most vegetable oils, and are liquids at room temperature
9like cooking oil and solid cocoa butter)
unsaturated triacylglycerols
have 1 C=C bond
monounsaturated triacylglycerols
have many C=C bonds
polyunsaturated triacylglycerols
the increase of the number of double bonds in the fatty acid chain affects the melting point in the triacylglycerol in what way?
decreases its melting point
fats have ____ melting points and they are _____ at room temperature
higher, solid
where are fats derived from and how many double bonds do they have?
they are derived from fatty acids with few double bonds
examples of fats
lard and tallow (animal fats)
examples of fats
lard and tallow (animal fats)
oils have ____ melting points and they are _____ at room temperature
lower, liquids
where are oils derived from and how many double bonds do they have?
they are derived from fatty acids and have a larger number of double bonds
used to build cell membranes, insulate the body, and store energy for later use
fats
how much should a person’s caloric intake come from lipids?
no more than 20-35%
what is linked to heart disease?
saturated tiacylglycerols
stimulate cholesterol synthesis, which can lead to cholesterol paques building up inside arteries
saturated fats
lowers the risl of heart disease by decreasing the level of cholesterol in the blood
unsaturated triacylglycerols
where are triglycerols formed from wherein they are very helpful in lowering the risk of heart attack
omega-3 fatty acids
what happens if the double bond of the unsaturated triacylglycerol is trans?
the beneficial effect is lost
primarily synthesized instead of naturally occurring, act like saturated fats, and increase the cholesterol levels in the blood
trans fats
what can hydrolyze triacylglycerols?
acid, bases, or enzymes (in the body)
where do humans store triacylglycerols?
in adipose cells below the surface of the skin, in the breast area, and surrounding internal organs
what is the relation of adipose cells to its weight?
adipose cell numbers are constant, they may swell or shrink but do not change in numbers
what to do in order to metabolize triaclyglycerols for energy?
the esters are hydrolyzed by enzymes called lipases
what does complete metabolism of a triacylglycerol yield?
CO2, H2O, and a great deal of energy
esters of fatty acid, alcohol, and another compound
compound lipid
makes up phospholipids
fatty acid and alcohol plus a phosphoric acid reside (phosphate)
frequently have nitrogen containing bases and other substituents such as
glycerophospholipids and sphingophospholipids
alcohols of glycerophospholipids
glycerol
alcohols of sphingophospholipids
sphingosine
fatty acid and sphingosine plus carbohydrate
glycolipids (glycosphingolipids)
other complex lipids
sulfolipids and aminolipids
lipoprotein
what atom does phospholipids contains
P atom (phosphorous)
two common types of phospholipids
phosphoacylglycerols and sphingomyelins
phospholipids are main constituents of…
our plasma membrane
where are phospholipids derived from?
phosphatidic acid
how is phosphate esterified?
with the -OH of a suitable alcohol
intermediate in the synthesis of triacylglycerols
phosphatidic acid
main component of most cell membranes
phosphoacylglycerols
structurally, they resemble a ____ except the third fatty acid has been replaced with a ______
triacylglycerol, a phosphodiester bonded to an alcohol
main types of phosphoacylglycerols is
cephalin (phosphatidylethanolamine) and lecithin (phosphatidylcholine)
most abundant phospholipids of the cell membrane and represent a large proportion of the body’s store of choline
phosphoaclyglycerol containing choline (lecithins -. egg yolk)
supplement that lecithins are used as
lipid lowering
important in nervous transmission and as a store of labile methyl group
choline
what is the form of choline in nervous transmissions and storage of labile methyl groups?
acetylcholine
effective surface-active agent
dipalmitoyl lecithin
what is dipalmitoyl lecithin a major constituent of due to the surface tension of the inner surfaces of the lungs?
surfactant preventing adherence
absence of dipalmitoyl lecithin can lead to
respiratory distress syndrome
precursor of second messenger
phosphatidylinositol (IPC)
what is inositol present as a sterioisomer?
myoinositol
important constituent of cell membrane phospholipids
phosphatidylinositol 4,5-biphosphate
what can phosphatidylinositol be cleaved into?
diacylglycerol and inositol triphosphate (internal signals or second emssenger)
bisphosphatidyl glycerol
cardiolipin
what is cardiolipin an important component of and what percent of lipids does it constitute?
the inner mitochondrial membrane and 20% of the total lipid
cardiolipins serves as an _____ and stabilizes the activity of ___________ important to the electron transport chain
insulator, protein complexes
intermediates in the metabolism of phosphoglycerols
lysphospholipids
what is the importance of lysphospholipids to phospholipids?
metabolism and interconversion (lysphosphatidylcholine)
where can you find lysphospholipids?
oxidized lipoproteins and can promote atherosclerosis
instead of a glycerol backbone, sphingomyelins contain
a sphingosine backbone instead
do sphingomyelins contain an ester?
no, their single fatty acid is bonded to the backbone by an amide bond
10% of the phospholipids of the brain and muscle
plasmalogens
what do plasmalogens resemble?
phosphatidylethanolamine (ether linked)
alkyl radicals in phosphatidylethanolamine is
and unsaturated alcohol
may be substituted for ethanolamine
choline, serine, or inositol
found in large quantities in brain and nerve tissues
sphingomyelins
what does sphingomyelins yield?
fatty acid, phosphoric acid, choline, and a complex amino alcohol, sphingosine
what coating that surrounds nerve cells is rich in sphingomyelins?
myelin sheath
sphingosine plus amino acid
ceramide
where are ceramides often found in?
glycosphingolipids
distributed in every tissue of the body (nervous tissues and plasma membrane)
glycolpids
major glycolipids in animal tissues
glycosphingolipids
glycosphingolipids are composed of
ceramide + sugar
major sphingolipid of brain and other nervous tissue
galactosylceramide
complex glycosphingolipids derived from glucosylceramide that contain in addition one of more molecules of sialic acid
gangliosides
principal sialic acid found in human tisses
neuraminic acid
abbreviation of gangliosides and is the simplest in tissues
Gm3
simple and compound lipid upon hydrolysis
derived lipid
non hydrolyzable lipid that is a group of lipids whose carbon skeletons contain several infused rings
steroids
the most prominent steroid and found in almost all body tissues
cholesterol
where is cholesterol commonly synthesized ?
in the liver
a molecule that is synthesized in one part of an organism, which then elicits a response at a different site
hormone
two important classes of steroid hormones
sex hormones and adrenal cortical steroids
female sex hormones
estrogens and progestins
male sex hormones
androgens
control development of secondary sex characteristics, regulate the menstrual cycle, and are made in the ovaries
estradiol and estrone
“pregnancy hormone” and is responsible for the preparation of the uterus for implantation of fertilized egg
progesterone
androgens made in the testes
testosterone and androsterone
synthetic androgen analogues that promote muscle growth
anabolic steroids
compared to testosterone, anabolic steroids are
more stable, so they are not metabolized as quickly
examples of adrenal cortical steroids are
aldosterone, cortisone, cortisol
regulates blood pressure and volume by controlling the concentration of Na+ and K+ in body fluids
aldosterone
serve as anti-inflammatory agents, which also regulate carbohydrate metabolism
cortisone and cortisol
side effects of prolonged use of steroids
like bone loss and high blood pressure
a synthetic alternative and has similar anti-inflammatory properties
prednisone
precursor of vitamin D2 and occurs in plants/yeast
ergosterol
derivative of ergosterol via UV light
viosterol -> ergocalciferol
what does egosterol require when irradiated with UV light?
antirachitic properties
all eicosanoids are very potent compounds, which are not stored in cells, but rather…
synthesized in response to external stimulus
unlike hormones, eicosanoids are ____, performing their function in the environment which they are synthesized
local mediators
carboxylic acids that contain a five-membered ring and have a wide range of biological activitiyes
prostaglandins
prostaglandins are responsible for…
inflammation
relieve pain and inflammation by blocking the synthesis of these molecules
aspirin and ibuprofen
other effects of prostaglandins
decrease gastric secretions, inhibit blood platelet aggregation, stimulate uterine contractions, and relax smooth muscles
two different cyclooxygenase enzymes responsible for prostaglandin synthesis
COX-1 and COX-2
involved in the usual production of prostaglandins
COX-1
responsible for additional prostaglandins in inflammatory diseases like arthrisis
COX-2
inactivates bot COX-1 and -2 but increase risks for stomach ulcer formation
NSAIDS like aspirin and ibuprofen
affect only the COX-2 enzyme without affecting gastric secretions
vioxx, bextra, and celebrex
helpful to reduce chronic inflammation
inhaled steroids
molecules that contribute to the asthmatic response by constricting smooth muscles of the lungs
leukotrienes
how do asthma drugs act?
by blocking the synthesis of leukotriene C4 which treat the disease instead of just the inflammation symptoms
not steroids but synthesized like cholesterol
polyprenoids
participates in respiratory chain in mitochondrion
ubiquinone
takes part in glycoprotein synthesis by transferring carbohydrate residues to asparagine residues of polypeptide
dolichol
rubber, camphor, fat soluble vitamin and B-carotene (provitamin A)
isoprenoid
basic unit of isoprenoid
isoprene (C5H8)
process where lipids are exposed to oxygen wherein a chain reaction providing a continuous supply of free radicals
auto-oxidation
effects of peroxidation
-rancidity/deterioration of food
-damage of tissue
catalyzed in vivo by heme compounds and by lipoxygenases (platelets leukocytes)
peroxidation
product of auto-oxidation that is formed from cholesterols
oxysterols
product of auto-oxidation that is formed from prostanoids
isoprostanes
control and reduce lipid peroxidation
antioxidants
antioxidants for food
propyl gallate, BHA, BHT
naturally occuring antioxidants
vitamin e, vitamin c, urate, beta-carotene
reduce the rate of chain initiation
preventive antioxidants
interfere with chain propagation
chain-breaking antioxidants
