Chapter 7: Lipids & Membranes Flashcards
where are lipids soluble
- in organic solvents
- sparingly in water
organis solvents: cholorform & methanol
list some lipid examples
- fats
- oils
- vitamins
- hormones
- non-protein membrane components
what are carboxylic acids w/ long chain hydrocarbon side groups?
fatty acids
fatty acids are rarely
free in nature
fatty acids occur as ________ ________ of various lipids
esterified components
about half of the fatty acid residues of plant animal lipids are
unsaturated
unsaturated lipids contain
double bonds
the most common fatty acids are of the
C16 & C18 species
saturated chains of fatty acids are packed ____ and form more…
tightly
rigid organized aggregates
aggreagte ex: membranes
unsaturated chains of fatty acids ________ and are packed in a ______ ______ way with greater potential for ________.
bend
less
ordered
motion
in unsaturated fatty acids the 1st double bond occurs between
C9 and C10
what rarely occurs in fatty acids
triple bonds
in unsaturated fatty acids the 2nd double bond occurs between
C12 and C13
fats and oils in plants and animals consist of mixtures of
triacylglycerols
Triacylglycerols are ______, water _______ substances
nonpolar
insoluble
triacylglycerols consist of fatty acid triesters of
glycerol
characteristics of triaclyglycerols
- energy reservoirs
- most abundant lipid
triacylglycerol are NOT components of
membranes
simple triacylglycerols contain
only 1 type of fatty acid
what type of triacylglycerol is most common in nature
mixed
what are major lipid components of biological membranes
glycerophospholipids
sphingolipids
glycerophospholipids are ________ molecules. Why?
amphiphilic
b/c of nonpolar aliphatic tails & polar phosphoryl head groups
on a glycerophospholipid saturated C16 and C18 fatty acids typically occur at the
C1 position
on a glycerophospholipid unsaturated fatty acids typically occur at the
C2 position
name this phospholipid head group
-H
phosphatidic acid
name this phospholipid head group
-CH2CH2NH3+
phosphatidylethanolamine
name this phospholipid head group
-CH2CH2N(CH3)3+
phosphatidylcholine
A C12 saturated fatty acid is named
lauric acid
A C14 saturated fatty acid is named
myristic acid
A C16 saturated fatty acid is named
palmitic acid
A C18 saturated fatty acid is named
stearic acid
A C16 fatty acid w/ 1 point of unsaturation is called
palmitoleic acid
A C18 fatty acid w/ 1 point of unsaturation is called
oleic acid
A C18 fatty acid w/ 2 points of unsaturation is called
linoleic acid
ether glycerophospholipids contain an _____ linkage at the _____ carbon of glycerol
ester
C1
give 2 examples of ether glycerophospholipids
- plasmalogens
- PAF
PAF: platelet activating factor
plasmalogens are ether glycerophospholipids in which the
alkyl chain is unsaturated
PAF is a ether glycerophospholipid in which the
alkyl chain is saturated
choline plasmalogens are found in
various tissues like heart muscle
PAF is a potent
biochemical signal molecule
PAF has a short ______ moiety at the ____ position that allows for….
acetate
C2
increased solubility
sphingolipids are derivatives of
sphingosine (C18 amino alcohols)
how is a ceramide formed
fatty acids joined to sphingosine through amide linkage
what is the most common sphingolipid
sphingomyelins
sphingomyelins are ceramides with either a
phosphocholine or phosphoethanolamine
sphingomyelins are found in
myelin sheaths
what is the simplest sphingoglycolipid
cerebrosides
cerebrosides are ceramides w/
1 or more sugars in β glycosidic linkage at the 1-OH group
what type of cerebroside is prevalent in neuronal cell membranes of the brain
galactocerebrosides
what type of cerebroside is prevalent in cell membranes of various other tissues
glucocerebrosides
what is the most complex group of sphingoglycolipid
ganglioside
gangliosides must include at least
1 sialic acid residue
what hereditary disease is a result of the unavailability to break down sphingoglycolipid
Tay-Sachs disease
which sphingoglycolipid is associated w/ tay-sachs disease?
Gm2
steroids are derivatives of a molecule containing
4 fused saturated rings
cholesterol is a
sterol lipid
what is the most common steroid in animals and the precursor for all other steroids in animals
cholesterol
examples of cholesterol precursors are
cortisol
testosterone
estradiol
progesterone
glycerophospholipids and sphingolipids play important roles as
chemical signals
the lifetimes of signals generated by glycerophospholipids and sphingolipids are usually
very short
what cleaves fatty acids from a glycerophospholipid
phospholipases A1 & A2
cleaving fatty acids from a glycerophospholipid produces
lysophospholipids
what hydrolyzes on either side of the phosphate in the polar head
phospholipases C & D
hydrolyzation by phospholipases C & D produces
various signaling molecules
what is a phosphorylated sphingosine
sphingosine-1-phosphate (S1P)
what are formed from amphiphilic molecules
micelles
In order to form micelles the ____ must be met
critical micelle concentration (CMC)
what is the critical micelle concentration
the # of amphiphilic molecules needed to form micelles
a higher CMC concentration indicates
smaller single hydrophobic tails
a lower CMC concentration indicates
larger double hydrophobic tails
liposomes are formed by
sonification of multilamellar vesicles to form unilamellar vesicles
what are 2 examples of clinically approved liposomal-based drugs
Daunoxome
Doxil
lipid bilayers are extremely impermeable to
polar and ionic substances
what is transverse diffusion?
rare event of lipid transfer across the bilayer
define transition temperature
temp. at which phospholipids undergo a phase change
lipids are _______ above to transition temp.
mobile (fluid-like)
lipids are ______ below the transition temp.
less mobile (gel-like)
the transition temp. of a lipid bilayer increases with
chain length & degree of saturation
longer tail = higher ….. = higher …..
hydrophobic interactions
transition temp
integral proteins are bound to membranes via
hydrophobic forces
peripheral proteins associate w/ the membrane by binding to
lipid head groups or integral proteins
peripheral proteins bind to lipid head groups/ integral proteins through
electrostatic interactions or hydrogen bonding
what are known as compounds that cannot be synthesized in sufficient quantities by an organism
vitamins
list fat soluble vitamins
A, D, E, K
vitamin A is also known as
retinol
vitamin A is generated by
enzymatic action in the liver from β carotene
abundant in carrots
vitamin A serves as the site of the primary photochemical reaction in
vision
vitamin D is abundant in
milk
how is vitamin D formed?
from cholesterol by the action of UV radiation
deficiency in vitamin D can lead to
rickets
what is the most active form of vitamin E
α-tocopherol
vitamin E is an
antioxidant
Vitamin K is an
important factor in the blood clotting process
