Biochem Ch 11 Textbook Online quiz q's "Lipids"
Terms in this set (10)
1) Lipid molecules are said to be amphipathic, meaning that:
A) they have asymmetric carbons and can exist in left- and right-handed forms.
B) they have a dual nature with part of the molecule being hydrophobic and the other part hydrophilic.
C) they are capable of moving rapidly from one side of a lipid bilayer to the other.
2) Unsaturated fatty acids have double bonds that are in the cis, rather than the trans, configuration. One of the consequences of this is:
A) an alteration in the charge of the molecule.
B) an alteration in the number of carbons in the molecule.
C) a bend in the molecule.
C (A cis double-bond produces a bend in molecule)
3) In phosphoglycerides, fatty acids are esterified at:
A) glycerol carbons 1 and 3.
B) any two of the three glycerol carbons.
C) glycerol carbons 1 and 2.
4) Which of the following is NOT a difference of archaeal membrane lipids relative to those of other organisms?
A) The long hydrophobic tails are branched rather than being linear.
B) Fatty acid esters are replaced with long chain alcohol ether links to the glycerol.
C) A backbone other than glycerol is used.
5) Of the three major types of membrane lipids, which is not found in prokaryotes?
A (even within eukaryotes, cholesterol is mainly limited to mammals)
6) Which of the following would be expected to lower the Tm for a phospholipid bilayer?
A) Replacing a lipid containing 18-C fatty acids with one containing 16-C fatty acids
B) Replacing a lipid containing unsaturated fatty acids with one containing saturated fatty acids
C) Adding ions to bind to charged groups in the polar head groups
A (shorter chain FA's have weaker intermolecular interactions than longer FAs; the weakened interaction should lower the Tm)
7) How many carbons do naturally occurring fatty acids typically have?
A) Exactly 6, 10, or 14 carbons
B) An even number of carbons, ranging from 14-24
C) An odd number of carbons, ranging from 13-25
B (F.A's from bio systems have an even # of carbons; most common FAs have 16 or 18 C's)
8) Which of the following is NOT true about lipids?
A) Lipids can be covalently attached to carbohydrates.
B) Lipids polymerize readily to form membranes.
C) Lipids are used by organisms to store energy.
B (Lipids do NOT polymerize, rather they self-associate to make noncovalent assemblies)
9) Niemann-Pick disease can result from:
A) a defect in farnesylation of certain membrane proteins.
B) lack of sphingomyelinase.
C) lack of docosahexaenoate (DHA).
B (Sphingomyelinase is an enzyme involved in degrading sphingomyelin)
10) Which of the following is NOT categorized as a phospholipid?
B (Eicosapentaenoate is name for ionized form of eicosapentaenoic acid "EPA," which has no phosphate group. EPA is example of a w-3 F.A., found in fish)