1. The molecule shown here is: (clue : see section 15.1.D – Pages 425-426 )
2. Which statement is TRUE? (clue: see section 15.1.C , Pg 423-424)
A. The sugar in this molecule is a 2' deoxy sugar.
B. This molecule is a nucleoside.
C. This molecule is guanosine.
D. This molecule contains deoxyribose.
1 3. RNA is susceptible to hydrolysis under alkaline conditions whereas DNA is not
because RNA contains ribose which enables the reaction. (Clue: see section 15.6.A, Pg
4. The primary structure of DNA is stabilized by covalent bonds. (section 15.2.A
page428 paragraph 1, link:
5. DNA absorbs ultraviolet radiation with a peak at 260 nm, whereas RNA does not.
6. The primary structure of nucleic acids is said to have a "sense-of-direction." What does
this term describe? (Page:428 section 15.2.A, 2 paragraph)
A. One end of the nucleic acid has a free phosphate group and the other has a free
B. One end of the nucleic acid is called the 5' end and the other is called the 3' end.
C. The free ends of a nucleic acid are geometrically distinct from one another.
D. One strand of a nucleic acid is able to orient itself correctly relative to another.
2 The following graph shows the absorbance at 260 nm (A 260 nmby a series of pure DNA
standard solutions at various concentrations (μg/mL).
7. You have a sample which gives you an A 260nmreading of 0.090. The concentration of
DNA in this solution, assuming it is pure, would be which of the following?
A. 0.180 μg/mL
B. 90 μg/mL
C. 45 μg/mL
D. 180 μg/mL
8. You then measure the absorbance of the sample solution at 280 nm, and find that it is
0.048. What does this tell you? THE RATIO IS 1.875 WHICH IS APPROX. 1.9,
MEANING NO PROTEIN IS PRESENT.
A. The solution is contaminated with protein.
B. The solution is pure DNA.
C. The solution is not contaminated with protein.
D. The solution is not pure DNA.
3 9. In eukaryotic DNA, 5-methylcytosine (5-mC) may be found in place of cytosine in the
DNA double helix. Which of the following is 5-mC?
A. The molecule on the left.
B. The molecule in the middle.
C. The molecule on the right.
10. What is the name of the molecule shown above?(link:
http://en.wikipedia.org/wiki/File:Nucleotides_1.svg and page:426)
A. phosphoribosyl guanosine
B. guanosine monophosphate
C. phosphoribosyl adenosine
D. adenosine monophosphate
4 11. Complementary strands of DNA will spontaneously form a double-helix in aqueous
solution at pH 7 and room temperature. Which of the following is/are important in this?
(Section 15.2.C pages 431-432 and http://en.wikipedia.org/wiki/DNA#Properties
paragraph 4 )
A. The helix enables formation of a large number of hydrogen bonds through base
B. The helix maximizes base stacking interactions between strands.
C. The bases are subject to the hydrophobic effect.
D. A and C.
E. A, B and C.
Nucleic acid samples have been isolated from 3 different organisms and you have
measured the following base content.
% A T U G C
Sample 1 29 19 0 22 30
Sample 2 24 0 16 24 36
Sample 3 17 17 0 33 33
12. Which of these samples is/are DNA? (see page 429 section 15.2.B paragraph 1 . Base
A. 1 and 2
B. 1 and 3
C. 2 and 3
D. 2 only
13. Which of the nucleic acid samples above is a double-helix?
A. 1 and 2
B. 1, 2 and 3
C. 2 and 3
D. 3 only
E. 1 and 3