Unformatted text preview: 129} Nucleic acids have adefinite polarity. or directionality. Stated another way. one end of the
molecule is different from the other end. How are these endsdescribed? A] One end containsanitrogenous base; the other end IEKS it.
E] One end hasan unlinked 3csrbon; the other end hasan unlinked Scarbon. G} Oneend hasone phosphate group; theother end has two phosphate groups.
D} Oneend hasahydrosyl group on the 2 carbon; the other end hasahydrogen atom on the 2
carbon. 130} What feature of mononucleotides provides the energy needed for polymerization when nucleic
acids are formed? A] their sugar groups B] their nitrogenous bases
G} their phosphate groups D) their methyl groups 131} What is gel electrophoresis used for?
A} to separate mazromolecules by sizeor charge
B} to denature proteins for further analysis
G} to identify the first self- replicating molecule that formed during chemical evolution
D] to separate the two helices that make up the DNA double helix 132} Which of these scientistswas not directly involved in the discovery of DNA's structure?
A} MauriceWilkins B} Flosalind Franklin
0} James Watson D] Sidney Altman
E] Francis Crick 133} Which of the following best describes DNA's secondary structure? A} double patallel helical strands B] beta- pleated sheet
C} double antiparallel helical strands D) turn- loop-turn 134]. Which of the following did Watson and Crick already know when they were trying todetermine
the structure of DNA?
A} The number of purines is alwaysthe sameas the number of pyrimidines. B] The number of purines is always larger than the number of pyrimidines
G} The number of pyrimidines is always largerthan the number of purines. D} The number of guaninesisalways the same as the number of thymines.
E] The number of cytosines is alwaysthe sane asthe numberof adenines. 135} Franklin and Wilkins analyzed DNA by bombarding DNA crystals with X- ray s. Their analysis
yielded two numbers that sparked interest. 3.4 nm and 0.34 nm. thl isthe signiﬁcance of these
numbers? A} DNA moleculesare 3.4- nm long and 0.34 nm wide. B} It turned out to be just aooincidence. C} These numbers tell us there are 1D rungs. or step s. on the DNA 'ladder‘ for every turn of the
helix. D] The width of aDNA molecule is 3.4 nm. whereas thewidth of a nucleotide monomer is
0.54m. E] The tU—to—t ratio signifies that DNA molecules are ten times longer than they are wide. 19 129} 130} 131} 132} 1 as} 134} 1 35} ...
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- Spring '07