Question 1

The oligonucleotide AGGUCCAUUGAAp,is best described as

Accepted Answer

A)  an RNA oligonucleotide with a 3'phosphate 
B)  an RNA oligonucleotide with a 5'phosphate 
C)  a DNA oligonucleotide with a 3'phosphate 
D)  a DNA oligonucleotide with a 5'phosphate

Question 2

The human genome has 3 × 109 base pairs (bp) of DNA If this were one continuous molecule and extended such that each nucleotide was separated from the adjacent nucleotide by 4 Å,as proposed in the Watson and Crick model,what would the end-to-end distance be?

Accepted Answer

A)  1 meter 
B)  1 centimeter 
C)  1000 centimeters 
D)  1014 Å

Question 3

Which best describes the relationship between the nucleobases in a piece of DNA?

Accepted Answer

A)  They are parallel to the helical axis. 
B)  They are perpendicular to the helical axis. 
C)  They are randomly oriented with respect to the helical axis.

Question 4

Which of the following statements concerning the B-form of DNA is false?

Accepted Answer

A)  It twists in a left-handed direction. 
B)  The distance between base pairs is 3.4Å. 
C)  The width of a base pair is about 1.1 nm. 
D)  The diameter, including the phosphate, is about 20 Å.

Question 5

Which contains a phosphoanhydride bond?

Accepted Answer

A)  DNA 
B)  RNA 
C)  ATP 
D)  AMP

Question 6

Topoisomerases are associated with

Accepted Answer

A)  production of RNA from DNA. 
B)  joining of nucleotide monomers to make polynucleotides. 
C)  supercoiling of DNA. 
D)  ribosomes.

Question 7

Hydrophobic bonding via pi-clouds is referred to as

Accepted Answer

A)  base stacking. 
B)  propeller twist. 
C)  hyperchromicity. 
D)  supercoiling.

Question 8

Eukaryotic and prokaryotic ribosomes can be compared in all these ways,except:

Accepted Answer

A)  Both have large and small subunits. 
B)  Eukaryotic ribosomes are larger. 
C)  Both contain the same number of RNA molecules. 
D)  Eukaryotic ribosomes contain more proteins. 
E)  All of these statements are accurate comparisons.

Question 9

Which of the following modifications is likely to happen to the mRNA in a eukaryotic cell?

Accepted Answer

A)  capping of the 5' end 
B)  addition of a poly-A tail to the 3' end 
C)  removal of intervening sequences (introns) 
D)  All of the above occur in eukaryotic cells.

Question 10

Deoxyadenylate (dA) is a:

Accepted Answer

A)  purine base 
B)  pyrimidine base 
C)  purine based nucleoside 
D)  purine based nucleotide

Question 11

The outside diameter of a piece of DNA is closest to

Accepted Answer

A)  2 Å. 
B)  20 Å. 
C)  200 Å. 
D)  2000 Å.

Question 12

Which of the following best describes the structure of a nucleosome?

Accepted Answer

A)  DNA wrapped around an octomer containing two each of H2A, H2B, H3, and H4 with H1 on the outside. 
B)  DNA wrapped around an octomer of H1 with H2A,B, H3 & H4 on the outside. 
C)  DNA wrapped around a octomer of either H2A/H2B or H3/H4 with H1 on the outside. 
D)  DNA wrapped around a tetramer of either H2A/H2B or H3/H4 with H1 on the outside.

Question 13

Calculate the length/diameter ratio for the extended E.coli DNA (4 Å between adjacent nucleotides).

Accepted Answer

A)  4 × 105 
B)  1 × 105 
C)  3 × 108 
D)  3 × 106

Question 14

Supercoiling of DNA

Accepted Answer

A)  is not observed in prokaryotes 
B)  requires the action of topoisomerase enzymes 
C)  does not require ATP 
D)  is not observed in eukaryotes

Question 15

The nucleotide sequence of DNA is which level of structure?

Accepted Answer

A)  primary 
B)  secondary 
C)  tertiary 
D)  quaternary

Question 16

Which of the following statements concerning ribosomes is true?

Accepted Answer

A)  They consist of two RNA subunits, one of which is larger than the other. 
B)  They contain both RNA and protein. 
C)  They can be dissociated and reassembled by controlling the Mg2+ concentration of the medium. 
D)  All of these are true.

Question 17

Which of the following is not true?

Accepted Answer

A)  The amount of UV absorbance increases, but the wavelength does not change as DNA nears its melting point 
B)  Once DNA is denatured, it cannot renature 
C)  The melting temperature partially depends on the GC content 
D)  The nature of the solvent the DNA is in can affect the melting temperature

Question 18

Eukaryotic mRNA requires

Accepted Answer

A)  less processing after synthesis than prokaryotic mRNA. 
B)  more processing after synthesis than prokaryotic mRNA. 
C)  about the same amount of processing after synthesis as prokaryotic mRNA.

Question 19

Which of the following nucleobases is a purine?

Accepted Answer

A)  adenine 
B)  cytosine 
C)  thymine 
D)  uracil

Question 20

Transfer RNA molecules are characterized by all the following,except:

Accepted Answer

A)  They are one of the largest of the RNAs. 
B)  Cloverleaf shape. 
C)  Many modified bases. 
D)  Extensive secondary and tertiary structure. 
E)  All of these characterize transfer RNA molecules.

Exam 9: Nucleic Acids: How Structure Conveys Information