biomolecules lipid
TRANSCRIPT
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Lipids
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LIPIDSA broad group of naturally occurring molecules which
includes fats, waxes, sterols, fat-soluble vitamins,monoglycerides, diglycerides, phospholipids andothers.
Function as energy storage, as structural componentsof cell membranes and as important signaling
molecules.
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Classes of LipidsAll biological lipids are amphipathic (contain
polar and nonpolar in structure)
Fatty acidsTriacylglycerols
Phospholipids
SphingolipidsWaxes
Isoprene-based lipids (including steroids)
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Lipids Open chain:
long nonpolar tail with a polar head
OH
Oeg. A fatty acid
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1. Fatty acids Monocarboxyc acids contain HC chains of variable
lengths (12-20 C)
Important components of several types of lipidmolecules
Saturated (C-C) chains pack tightly and form morerigid, organized aggregates (i.e., membranes)
Unsaturated (C-C, C=C or more) chains bend and packin a less ordered way, with greater potential for motion
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Saturated Fatty acidsKnow the common names and structures for fatty
acids up to 20 carbons long
Saturated
Lauric acid
Myristic acid
Palmitic acid Stearic acid
Arachidic acid
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Saturated Fatty Acids
Lauric acid: a typical saturated fatty acidwith 12 carbons
in the chain(in salt form) Fatty acid: 12-20 carbons, even # carbons, no branching,
nonpolar carbon chain, polar COO-group (as anion).
CH3
CH2CH
2
CH2CH
2
CH2CH
2
CH2CH
2
CH2CH
2
C
O
O
Nonpolar hydrophobic tail
Polar hydrophilic head
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Unsaturated Fatty acids Palmitoleic acid (16:1) Oleic acid (18:1)
Linoleic acid (18:2)
-Linolenic acid (18:3)
-Linolenic acid (18:3)
Arachidonic acid (20:4)
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Unsaturated Fatty Acids The first double bond is usually at the ninth carbon. The
double bonds are not conjugated and are usuallycis.
CO
OCH
2CH2
C C
CH2
CH2
CH2
CH2
CH2
CH2
HH
CH2
CH2
CH2
CH2
CH3
Palmitoleic acid, salt form
Cis double bond results
in a bent chain and lower mp.
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2. TriacylglycerolsAlso called triglycerides
Esters of glycerol with three FA
No charge-neutral fatsA major energy source for many organisms
Why?
Most reduced form of carbon in nature
No solvation needed
Efficient packing
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TriacylglycerolsWhen all three alcohol groups of
glycerol form esters with fatty acids, atriacylglycerol (triglyceride) is formed.
CH2
CH
CH2
O
O
O C
O
CO
C
OR1
R2
R3
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Triacylglycerols
TAGs which are solids at room temperature are richin saturated acids and are called
TAGs which are liquids at room temperature arerich in unsaturated acids and are called
e.g. oil seeds include peanut, corn, safflower, palm, andsoybean.
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Triacylglycerols
Triacylglycerols store fatty acids as fats in animal bodies.
Fat provide insulation in low temperature (poorconductor of heat)
Before a fat can be oxidized, it must be hydrolyzed to the
Biologically this is done by lipases. Chemically base hydrolysis is called saponification.
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3. Phospholipids
Have hydrophobic and hydrophilic domains.
Structural components of membranes
Emulsifying agents
Suspended in water they spontaneously rearrange intoordered structures
Hydrophobic group to center
Hydrophilic group to water (Basis of membrane structure)
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Phospholipid molecules in aqueous
solution
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Glycerophospholipids
Essential components of cell membranes and arefound in small concentrations in other part of cells
Neural tissue (including brain) contain high amounts
of glycerophospholipids Involved in metabolism and cell signaling.
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Glycerophospholipids Examples:
Phosphatidyl(choline)
Phosphatidyl(ethanolamine)
Phosphatidyl(serine)
found in biological membranes
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4. SphingolipidsA class of lipids containing a backbone of sphingoid
bases, a set of aliphatic amino alcohols that includesphingosine.
Discovered in brain extracts in 1870
Play important roles in signal tranmission and cellrecognition.
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Sphingolipids These lipids are based on _____________, are found in plants
and animals, and are common in the nervous system.
CH CH CH2 CH3
CH OH
CH NH2
CH2OH
12
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TYPES OF SPHINGOLIPIDSCeramides:
Produce in mammalian cells and in plants
Most simple sphingolipids The other sphingolipids are derivaties of ceramides
such as glycolipids.
Glycolipids are large group of sphingolipids because
they contain one or more molecules of sugar.
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Glycolipids
are lipidswith a carbohydrateattached. Their role is to
provide energyand also serve as markersfor cellularrecognition
Frequently a glucose or galactose is bound to theprimary alcohol of a ceramide. The compound is called
a cerebroside. The carbohydrates are found on the outer surface of all
eukaryoticcell membranes.
They extend from the phospholipid bilayer into the
aqueous environment outside the cell where it acts as arecognition site for specific chemicals as well as helpingto maintain the stability of the membrane and attachingcells to one another to form tissues.
http://en.wikipedia.org/wiki/Lipidshttp://en.wikipedia.org/wiki/Carbohydratehttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Genetic_markerhttp://en.wikipedia.org/wiki/Cell_(biology)http://en.wikipedia.org/wiki/Eukaryotichttp://en.wikipedia.org/wiki/Biological_tissuehttp://en.wikipedia.org/wiki/Biological_tissuehttp://en.wikipedia.org/wiki/Eukaryotichttp://en.wikipedia.org/wiki/Cell_(biology)http://en.wikipedia.org/wiki/Genetic_markerhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Carbohydratehttp://en.wikipedia.org/wiki/Lipids -
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The carbohydrate structure of the glycolipid is
controlled by the glycosyltransferases that add thelipids and glycosylhydrolases that modify the glycanafter addition.
Sphingolipidosescan be associated with defects in
metabolism.
l l
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Glycolipids
O
CH2OH
HH
OHH
OH
OH
HH
OCH CH CH2 CH3CH
OHCHNH
CH2 12
C O
R1 A cerebroside
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5. Waxes
Esters of long-chain alcohols with long-chain fatty acids
Highly insolubleAnimal skin and fur are wax-coated
Leaves of many plantsBird feathers
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Wax EstersWaxes are typically esters of fatty acids and fatty
alcohols. They protect the skin of plants and fur of
animal
Examples of waxes include carnuba, from the leavesof the Brasilian wax palm, and beeswax.
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6. Isoprenoids The five-carbon unit that constitutes the basic building block
of isoprenoids is a hydrocarboncalled isoprene
CH2C
CH3
CH CH2CH
2C
CH3
CH2CH
2O P
O
OP
O
O
OOisoprene unit isopentenyl-pyrophosphate
http://www.britannica.com/EBchecked/topic/278321/hydrocarbonhttp://www.britannica.com/EBchecked/topic/296480/isoprenehttp://www.britannica.com/EBchecked/topic/296480/isoprenehttp://www.britannica.com/EBchecked/topic/278321/hydrocarbon -
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Isoprenoids two or more units of hydrocarbons, with each unit
consisting of five carbonatoms arranged in a specificpattern
Plant terpenoids used for their aromatic qualities
Play role in traditional herbs remedies and underinvestigations for antibacterial, antineoplastic and
pharmaceutical functions. pigmentsand fragrances tovitaminsand precursors of
sex hormones
http://www.britannica.com/EBchecked/topic/278321/hydrocarbonhttp://www.britannica.com/EBchecked/topic/94732/carbon-Chttp://www.britannica.com/EBchecked/topic/460189/pigmenthttp://www.britannica.com/EBchecked/topic/630930/vitaminhttp://www.britannica.com/EBchecked/topic/536988/sex-hormonehttp://www.britannica.com/EBchecked/topic/536988/sex-hormonehttp://www.britannica.com/EBchecked/topic/630930/vitaminhttp://www.britannica.com/EBchecked/topic/460189/pigmenthttp://www.britannica.com/EBchecked/topic/94732/carbon-Chttp://www.britannica.com/EBchecked/topic/278321/hydrocarbon -
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Terpenes
Large and diverse class of organiccompounds produced by variety of plants,particularly connifer
Major components of resin
Roles as end products in many organism,major biosynthetic building blocks withinnearly every living creature.
When modifies chemically, such as byoxidation or rearrangement carbonskeleton - isoprenes
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Terpenes
OH geraniol
farnesene
phytol
-carotene
OH
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Steroids Found in plants, animals and fungi.
Made in cell either from the sterol lanosterol (animalsand fungi) or from cycloartenol (plants).
Steroid hormones serve many functions in animals -
including salt balance, metabolic function and sexualfunction
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Steroids Steroid lipids are based on the ring system shown below.
1
2
3
4
56
7
8
910
11
1213
14 15
16
17
A B
C D
St id E l
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Steroid Examples
CH CH2
CH2
CH2
CH(CH3
)2
OH
H
CH3 H
CH3
H
H
H
CH3
Cholesterol
O
CH3
CH3
OH
testosteroneCH3
CH3
C
CH3
O
progesterone