Lipids Flashcards
Water insoluble biomolecule
Lipids
Lipids are insoluble in water, but soluble in _________ solvents including diethyl ether, dichloromethane, and acetone
organic
energy storage and metabolic fuels (fatty acids)
lipids
act as functional and structural components of the cell membrane
lipid bilayer
lipoproteins (e.g. LDL & HDL) are a mean for
__________ lipids in blood
transporting
building block of complex lipids
Fatty acyls
long-chain monocarboxylic acids
fatty acids
contains only single C–C bonds
Saturated Fatty Acid
contains one or more double C=C bonds
Unsaturated Fatty Acid
high melting points
Saturated Fatty Acid
low melting points
Unsaturated Fatty Acid
waxy solids at RT (animal fats)
Saturated Fatty Acid
liquids at RT (vegetable fats)
Unsaturated Fatty Acid
a group of signal lipids; derived from the metabolism of arachidonic acid by the enzyme cyclooxygenase (COX)
Eicosanoids
- derived mainly from arachidonic acid
- have a variety of potent biological activities of hormonal or regulatory nature
- parent compound is prostanoic acid
- control blood pressure
- stimulate muscle contraction
- inhibit platelet aggregation
- induce inflammation
Prostaglandins
induces platelet aggregation and vasoconstriction
Thromboxane A2
inhibit the synthesis of thromboxanes by inhibiting the COX enzyme
Aspirin and other NSAIDs
- occur mainly in leukocytes
- produce muscle contractions, especially in the lungs and thereby can cause asthma-like attacks
- In this regard, they are 100 times more potent than histamine
- Several recently-developed anti-asthma drugs inhibit the synthesis of leukotrienes
Leukotrienes
comprise the bulk of storage fat; triacylglycerides (TAGs)
glycerolipids
lipids formed by esterification of three fatty acids to glycerol
Triacylglycerols
reaction of a triacylglycerol with a base producing glycerol and three molecules of fatty acids
Saponification
- Simply, “phospholipids”
- Comprise the lipid bilayer in cells
- Involved in metabolism and signaling
glycerophospholipids
- most abundant lipid in most membranes
- have a polar head and two nonpolar tails
- control cell permeability
Phosphoacylglycerol
- Abundant in brain and nerve tissues
- Found in egg yolk, wheat germ, yeast
Phosphoacylglycerol
where is lecithin found?
Phosphatidylcholine
where is cephalin found?
Phosphatidylethanolamine
where is cardiolipin found?
Diphosphatidylglycerol
- the second large class of membrane lipids
- have a polar head and two nonpolar tails
- abundant in nervous system
Sphingolipids
- contain phosphocholine or phosphoethanolamine as their polar head
- found in the myelin sheath
Sphingomyelin
a carbohydrate is bound to an alcohol group of a lipid by a glycosidic linkage
Glycolipids
- “sterol alcohols”
- signaling molecules located along the membrane
sterol lipids
- contains aromatic alcohol which are derivatives of steroid nucleus
- steroid nucleus
- 3 cyclohexane rings (6 sides)
- 1 cyclopentane ring (5 sides)
Steroids
- precursor for the synthesis of other steroids
- weakly amphipathic
- bulky & rigid and fits into membrane lipids disrupting membrane regularity
- derived from squalene, a C30 terpenoid HC
Cholesterol
C3 –OH can be esterified to form
Cholesteryl esters
- Cellular membranes
- Myelin sheath, brain, and nerve tissue
- Bile salts
- Hormones
- Vitamin D
Cholesterol in the body
- isoprenoids
- Variety of functions – general health benefits
- Examples: Terpenes, carotenoids, quinones, hydroquinone
- Polyprenols (dolichol)
Prenol Lipids
- isoprene derived natural metabolites
- insect and plant growth hormones
- plant’s pleasant odors
- lipid-like sugar carriers
Terpenes
- Fatty acid with a sugar backbone
- Glucosamine precursor
Saccharolipids
secondary metabolites of living organisms for survival; used as anti-microbial, anti-parasitic and anti-cancer
Polyketides
- esters of fatty acids with long chain alcohols
- completely insoluble in water
- water repellants
Waxes
- triacylglycerols (TAGs)
- sphingolipids
- waxes
- phosphoacylglycerols
- glycolipids
Saponifiable lipids (with fatty acids)
- steroids
- terpenes
- prostaglandins
- leukotrienes
- thromboxanes
Non-saponifiable lipids (without fatty acids)
isoprenoid alcohol that plays a key role in vision, control of animal growth, & stimulation of development of nervous system
Vitamin A
can either be consumed in diet (cod liver oil, fish livers, butter, eggs) or biosynthesize from b-carotene
Vitamin A
most abundant form is D3 (cholecalciferol); regulation of Ca & P metabolism, i.e. proper deposition of Ca3(PO4)2 in bone
Vitamin D
disease that results from the lack of Vit. D; bone malformation
Rickets
- has an antioxidant role = prevents attack of peroxides on unsaturated f.a. in membrane lipids
- found in eggs & vegetable oils (corn, peanut, wheat germ)
- deficiency: muscular dystrophy, creatinuria, anemia
Vitamin E (a-tocopherol)
Vitamin K1 (phylloquinone) found in ____
plants
- important in the lymphatic synthesis of prothrombin & protein factors in blood platelets
- deficiency: diminished intestinal absorption of lipids
Vitamin K
Vitamin K2 (menaquinone) found in ____
animals & bacteria
denature the proteins and disrupt the lipoprotein complexes of the egg yolk
Ethanol
used to remove neutral or least polar lipids
Hexane
provides a mild dehydration condition
Acetone
normal phase descending chromatography based on adsorption phenomenon
Column Chromatography of Lipids
Stationary Phase of Column Chromatography of Lipids
silica gel
- two-dimensional chromatography
- Normal phase ascending chromatography based on adsorption phenomenon
Thin Layer Chromatography of Lipids
Stationary Phase of thin layer Chromatography of Lipids
silica G-250
