Ch 17 Lipids Flashcards
biomolecules that contain fatty acids or a steroid nucleus
Lipids
soluble in organic solvents but not in water.
Lipids
an important feature in cell membranes, fat-soluble vitamins, and steroid hormones
Lipids
esters that can be hydrolyzed to give fatty acids and other molecules
sphingolipids
Triacylglycerols and glycerophospholipids contain the alcohol ___
glycerol
Sphingolipids contain the amino alcohol ___
sphingosine
Steroids, which have a completely different structure, do not contain ____ and cannot be hydrolyzed. They are characterized by the steroid nucleus of four fused carbon rings
fatty acids
3 cyclohexanes and 1 cyclopentane
steroid
Long carbon chain with a carboxyl group
fatty acids
long, unbranched carbon chains with a carboxylic acid group at the end
Fatty acids
typically 12–18 carbon atoms long.
Fatty acids
Fatty acids are ___ when they do NOT contain C=C double bonds in the carbon chain
saturated
Fatty acids are ____ when they contain C = C double bonds in the carbon chain.
unsaturated
Common saturated fatty acids
lauric (coconut)
myristic (nutmeg)
palmitic (palm)
stearic (animal fat)
Fatty acids can be monounsaturated, with only one double C = C bond in the carbon chain. Examples?
palmitoleic
oleic
Almost all naturally occurring unsaturated fatty acids have one or more ___ double bonds
cis
Saturated fatty acids
contain only single C — C bonds and fit close together in a regular pattern, with strong dispersion forces between carbon chains
In unsaturated fatty acids, __double bonds cause the carbon chain to bend or kink, giving the molecules an irregular shape and thus allowing fewer interactions between molecules
cis
The reduced interactions in fatty acids with cis bonds reduce the melting point of the molecules.
Humans cannot synthesize sufficient amounts of polyunsaturated fatty acids such as ___
linoleic acid, linolenic acid, and arachidonic acid
considered essential
are hormone-like substances produced in small amounts in most cells
Prostaglandins
differ by the substituents attached to the five-carbon ring.
are also known as eicosanoids, formed from arachidonic acid, a polyunsaturated fatty acid with 20 carbon atoms
Prostaglandins
have many functions, such as lowering or raising blood pressure and stimulating contraction and relaxation of the smooth muscle of the uterus
Prostaglandins
prostaglandin E (PGE) has a ___ group on carbon 9
ketone
prostaglandin F (PGF) has a ___ group on carbon 9
hydroxyl
When tissues are injured, ___ is converted to prostaglandins that produce inflammation and pain in the area
arachidonic acid
Nonsteroidal anti-inflammatory drugs (NSAIDs) block production of ___, decreasing pain and inflammation
prostaglandins
esters of glycerol, a trihydroxy alcohol, and fatty acids
triacylglycerols
formed when three hydroxyl groups of glycerol react with the carboxyl groups of three fatty acids
triacylglycerols
named by changing glycerol to glyceryl and naming the fatty acids as carboxylates.
triacylglycerols
The general formula of a triacylglycerol consists of three hydroxyl groups of glycerol forming ___ bonds with the carboxyl groups of three fatty acids
ester
To name the fatty acid formed with three stearic acids, the name becomes glyceryl tristearate. The common name of this compound is ___.
tristearin
___ are the major form of energy storage for animals
Triacylglycerols
have higher melting points than do unsaturated fatty acids because they pack together more tightly.
are usually found in animal fats, coconut oil, and palm oil
Saturated fatty acids
double bonds in unsaturated fatty acids react with hydrogen gas to produce carbon–carbon single bonds
hydrogen gas is bubbled through the heated oil typically in the presence of a nickel catalyst
hydrogenation reactions
Commercial hydrogenation = the addition of hydrogen is stopped before all the double bonds in a liquid vegetable oil become completely saturated.
the partial hydrogenation of a liquid vegetable oil changes it to a soft, semisolid fat.
the more saturated a product the ___ its melting point.
higher
Triacylglycerols are hydrolyzed (split by water) in the presence of strong acids such as HCl or H2SO4, or digestive enzymes called ____
lipases
is the reaction of a fat with a strong base such as NaOH in the presence of heat
splits triacylglycerols into glycerol and the salts of fatty acids
is the process of forming “soaps” (salts of fatty acids).
Saponification
gives solid soaps that can be molded into different shapes when mixed with NaOH
gives softer, liquid soaps when mixed with KOH
Saponification
The products of ester hydrolysis are glycerol and ____.
three fatty acids
The polar glycerol is soluble in water, but the fatty acids with their long hydrocarbon chains are not.
two fatty acids that form ester bonds with the first and second hydroxyl groups of glycerol.
a hydroxyl group that forms an ester with phosphoric acid, which forms another phosphoester bond with an amino alcohol
Glycerophospholipids
contains sphingosine instead of glycerol.
contains a fatty acid, phosphate, and an amino alcohol.
Sphingomyelin
Amino alcohols found in glycerophospholipids are?
choline, serine, and ethanolamine
ionized at pH 7.4
two types of glycerophospholipids that are abundant in brain and nerve tissues. Also found in egg yolk, wheat germ, and yeast.
Lecithin and cephalin
contain both polar and nonpolar regions that allow them to interact with polar and nonpolar substances
have a polar head containing the ionized amino alcohol and phosphate portion, which is strongly attracted to water
have a nonpolar hydrocarbon tail portion soluble only in nonpolar substances such as lipids
Glycerophospholipids
contain both polar and nonpolar regions that allow them to interact with polar and nonpolar substances
have a polar head containing the ionized amino alcohol and phosphate portion, which is strongly attracted to water
have a nonpolar hydrocarbon tail portion soluble only in nonpolar substances such as lipids
Glycerophospholipids
sphingosine, a long-chain amino alcohol that replaces glycerol
an amide bond formed by the amine group on sphingosine to a fatty acid
a hydroxyl group that forms an ester bond with phosphate, which forms another phosphoester bond to choline or ethanolamine.
Sphingomyelin
Sphingomylelins are abundant in what?
the white matter of myelin sheath
steroid nucleus consists of
three cyclohexane rings and one cylopentane ring, fused together.
rings designated as A, B, C, and D.
numbered carbon atoms beginning in ring A.
two methyl groups at positions 18 and 19.
has a hydroxyl group (— OH) on carbon 3
has a double bond between carbons 5 and 6
has methyl groups on carbons 10 and 13.
has an alkyl chain at carbon 17
Cholesterol
have polar and nonpolar regions that act like soaps to make fat soluble in water.
help in absorption of cholesterol.
Bile salts
Lipids are nonpolar and are made more soluble by combining them with glycerophospholipids and proteins to form water-soluble complexes called
lipoproteins
surround nonpolar lipids with polar lipids and protein for transport to cells.
are soluble in water because the surface consists of polar lipids
Lipoproteins
chemical messengers that serve as a communication system for the body
produced from cholesterol
sex hormones
adrenal corticosteroids
Steroid hormones
Steroids, which have a completely different structure, do not contain fatty acids and cannot be ___. They are characterized by the steroid nucleus of four fused carbon rings.
hydrolyzed
require a significant amount of energy and high temperatures to separate and melt.
saturated fatty acids
Nonsteroidal anti-inflammatory drugs (NSAIDs) block production of ____, decreasing pain and inflammation.
NSAIDs include?
prostaglandins
naproxen (Aleve and Naprosyn), ketoprofen (Actron), and nabumetone (Relafen).
A ___ is an ester of a long chain fatty acid and a long chain alcohol, each containing from 14 to 30 carbon atoms
wax
Vegetable oils have ___ melting points because they have a higher percentage of unsaturated fatty acids than do animal fats
low
The products of ester hydrolysis are glycerol and three fatty acids from?
triacylgyerol hydrolysis
Phospholipids are a family of lipids similar in structure to triacylglycerols; they include
glycerophospholipids and sphingomyelin
amino alcohol, phosphoric acid, glycerol, and two fatty acids comprise a typical?
The components of a typical glycerophospholipid
In a ____, a polar “head” contains the ionized amino alcohol and phosphate, while the hydrocarbon chains of two fatty acids make up the nonpolar “tails.”
glycerophospholipid
are produced by the adrenal glands located on the top of each kidney.
include aldosterone, which regulates electrolytes and water balance by the kidneys.
include cortisone, a glucocorticoid, which increases blood glucose level and stimulates the synthesis of glycogen in the liver
steroid hormones (adrenal corticosteroids)
