Lipids Flashcards
A family of substances classified together on the
basis of common solubility properties.
Lipids
Lipids are (1) ______ in water,but (2) ______ in organic solvents including diethyl ether, dichloromethane, and acetone.
(1) insoluble
(2) soluble
The roles of lipids in human biochemistry include:
• (1) ______
• (2) ______
• (3) ______
(1) Energy storage within cells
(2) Components of membranes in cells
(3) Chemical messengers
Lipids are classified into four groups based on their ______:
• Simple lipids (fats, oils, and waxes)
• Complex lipids
• Steroids
• Prostaglandins, thromboxanes, and leukotrienes
(1) Structures
The fatty acid components of triglycerides have certain things in common:
1. Practically all are (1) ______ carboxylic acids.
2. They range in size from about (2) ______ carbons.
3. They contain an (3) ______ number of carbon atoms.
4. Apart from the –COOR ester groups, triglycerides have (4) ______, except that some have one or more carbon–carbon double bonds in the fatty acid hydrocarbon chains.
5. In most fatty acids that have carbon–carbon (5) ______, the cis isomers predominate.
(1) unbranched
(2) 12 to 20
(3) even
(4) no functional groups
(5) double bonds
In most triglycerides, ______ different fatty acid components are present.
two or three
The ______ of triglycerides is caused by the long nonpolar hydrocarbon chains of the fatty acid components.
hydrophobic character
The ester groups, although polar, are buried within a nonpolar environment, which makes triglycerides ______.
insoluble in water
In triglycerides, all three ______ of glycerol are esterified with fatty acids.
hydroxyl groups
A triester of glycerol with three fatty acids.
Triglyceride
The physical properties of triglycerides depend on the ______.
fatty acid components
Melting points of fatty acids increases as the number of carbons in the hydrocarbon chains (1) ______ and as the number of double bonds (2) ______.
(1) increases
(2) decreases
Triglycerides rich in ______ are generally liquid at room temperature and are called oils
unsaturated fatty acids
Triglycerides rich in ______ are generally semisolids or solids at room temperature and are called fats.
saturated fatty acids
The reduction of some or all of the carbon-carbon double bonds of an unsaturated triglyceride using H2/transition metal catalyst, which converts a liquid triglyceride to a semisolid.
Hydrogenation
_______ and other ______ substitutes are produced by partial hydrogenation of polyunsaturated oils derived from corn, cottonseed, peanut, and soybean oils.
Margarine, butter
Complex Lipids: Phospholipids
• Contain an (1) _____, ______, and a ______.
• In (2) ______, the alcohol is glycerol.
• In (3) ______, the alcohol is sphingosine.
(1) alcohol, two fatty acids, phosphate ester
(2) glycerophospholipids
(3) sphingolipids
Glycolipids
• Complex lipids that contain a ______.
carbohydrate
Complex lipids form the (1) ______ around cells and around (2) ______ within cells.
(1) membranes
(2) small structures
In aqueous solution, complex lipids spontaneously form into a (1) ______, with a (2) ______ arrangement of lipid monolayers
(1) lipid bilayer
(2) tail-to-tail
• (1) ______ are in contact with the aqueous environment.
• (2) ______ are buried within the bilayer and shielded from the aqueous environment.
(1) Polar (hydrophilic) head groups
(2) Nonpolar (hydrophobic) tails
• The major driving force for the formation of lipid bilayers is (1) ______.
• (2) ______ prevent tight packing of the hydrophobic chains; the resulting liquid-like membrane allows for molecular transport across it.
(1) hydrophobic interaction
(2) Unsaturated fatty acids
______, also called ______, are membrane components of cells throughout the body.
Glycerophospholipids; phosphoglycerides
Glycerophospholipids
• The most abundant glycerophospholipids are derived from (1) ______, a molecule in which glycerol is esterified with two molecules of fatty acid and one of phosphoric acid.
• The fatty acid on carbon 2 of glycerol is usually (2) ______.
(1) phosphatidic acid
(2) unsaturated
