Chapter 10 - Biochemistry

chichi's version from 2017-05-08 23:02

Section 1

Question Answer
Which of the following statements concerning fatty acids is correct?One is the precursor of prostaglandins
Which of the following molecules or substances contain, or are derived from, fatty acid?beeswax, prostaglandins, sphingolipids, triacylglycerols
Which of the following statements is true of lipids?Most are simply polymers of isoprene
Which of the following contains an ether-linked alkyl group?Platelet-activating factor
Sphingosine is not a component of:cardiolipin

Section 2

Question Answer
Which of the following statements about membrane lipids is true?Some sphingolipids include oligosaccharides in their structure.
A compound containing N-acetylneuraminic acid (sialic acid) is:ganglioside GM2
Fatty acids are a component of:cerebrosides
Which of the following statements about sterols is true?All sterols share a fused-ring structure with four rings
Which of the following is NOT true of sterols?They are commonly found in bacterial membranes.

Section 3

Question Answer
Which of the following best describes the chloesterol molecule?amiphipathic
Tay-Sachs disease is the result of a genetic defect in the metabolism of:gangliosides
An example of a glycerophospholipid that is involved in cell signaling is:phosphatidylinositol
Which of the following is NOT a fat-soluble vitamin?vitamin c
Identify the molecule(s) derived from sterols.vitamin d

Section 4

Question Answer
Select the fatty acid in each pair that has the higher melting temperature.18:19, 18:0, 18:0
Describe the dependence of the melting point of a fatty acid upon (a) chain length and (b) unsaturation:All other things being equal, (a) the longer the acyl chain, the higher the melting temperature; and (b) the more unsaturation, the lower the melting temperature
What is the effect of a double bond on fatty acid structure?Most double bonds in fatty acid are in the cis configuration. This results in rigid bend in the hydrocarbon chain
In cells, fatty acids are stored as traicylglycerols for energy reserves. (a) What is the molecule to which fatty acids are esterified to form triacylglycerols? (b) Define the logic behind cells storing fatty acids in esterified form.(a) 3 fatty acids are esterified to glycerol. (b)Triacylglycerols are uncharged and insoluble in water. They form lipid droplets within adipocytes, which do not contribute to the osmolarity of the cystol in those cells, and do not require any water of hydration.
What is the most significant chemical difference between triacylglycerols and glycerophospholipids that leads to their different functions?Triacylglycerols are nonpolar hydrophobic molecules that can be stored in specialized nonaqueous cellular compartments. Glycerphospholipids are amphiphatic molcules that can serve as structural components of membranes, which have hydrophilic and hydrophobic regions.

Section 5

Question Answer
What are the chemical components of a biological wax, and what is their general structure?A wax consists of a long-chain fatty acid in ester linkage with a long-chain fatty alcohol
What chemical features distinguish a plasmalogen from a common glycerophospholipid?(1) The long-chain acyl group attached to a C-1 of glycerol is ether-linked in a plasmalogen, but in an ester-linked fatty acyl group in typical glycerophospholipids. (2) There is a double bond between C-1 and C-2 of this fatty acyl chain in plasmalogens, but not in other phospholipids
What chemical features distinguish a cerebroside from a ganglioside?A cerebroside has a single sugar residue joined to ceramide; a ganglioside has an oligosaccharide joined to ceramide

Section 6

Question Answer
Blood clottingthromboxanes
Necessary for sightvitamin A
Mediates pain and inflammationprostaglandins
Important component of myelin membranessphingolipids

Section 7

Question Answer
Explain the cause of hereditary diseases of sphingolipid metabolism, such as Tay-Sachs and Niemann-Pick diseasesThese diseases are the result of mutations in the genes that code for enzymes of sphingolipid breakdown. The mutant enzyme is defective and unable to catalyze its reaction in the metabolic pathway; this results in the accumulation of the metabolic intermediate that is the substrate for the enzyme
What do all these compounds have in common: vitamin A, vitamin K, ubiquinone, and dolichol?They are all lipids with potent biological activities derived from isoprenoid precursors.
Explain why extraction of lipids from tissues requires organic solventsLipids are either strongly hydrophobic or amphipathic. Because the solvent in tissues is water, lipids are mainly present in aggregates. This aggregation does not occur in organic solvents; as a result, the lipids are more soluble and thus extractable from the tissues.
If beeswax, cholesterol, and phosphatidylglycerol were dissolved in chloroform/methanol/water as the developing solvent, which would move fastest?In this chromatography, the least polar compound (beeswax) moves fastest and the most polar (phosphatidylglycerol, which has a negative charge on its head group) moves the slowest.

Section 8

Question Answer
Blood clottingVitamin K
VisionVitamin A
Ca2+ and phosphate metabolismVitamin D
Prevention of oxidative damageVitamin E