NAME: _____________________________DATE: ______________________ BLOCK: ____
1. In 1952, when Alfred Hershey and Martha Chase performed their famous experiment,
many scientists believed that __________ and not DNA was the genetic substance. If this
had been true, then the expected results of their experiment would have been that
radioactive __________ would have been detected inside the bacteria. (HINT: DNA
contains phosphorous and not sulfur.)
a. phosphorus ... phosphorus, but not sulfur
b. protein ... sulfur, but not phosphorus
c. sulfur ... sulfur, but not phosphorus
d. protein ... phosphorus, but not sulfur
2. One strand of DNA has the following sequence of nucleotides:
3'-ATTCGCTAT-5'. The base sequence on the other strand of DNA would be
a. 3'-ATTCGCTAT-5'
b. 5'-ATTCGCTAT-3'
c. 3'-TAAGCGATA-5'
d. 5'-TAAGCGATA-3'
e. 5'-GCCTATCGG-3'
3. Which one of the following is NOT true about double-stranded DNA?
a. It is helical.
b. It contains phosphodiester linkages (sugar – phosphate bond).
c. Adenine and uracil would be present in equal amounts.
d. The strands run antiparallel.
e. The two strands are said to be complementary.
f. None of the above.
4. Which of the following components is (are) required for DNA replication?
a. RNA polymerase
b. ribosomes
c. RNA primer
d. transfer rna
e. all of the above.
5. What enzyme joins Okazaki fragments?
a. helicase
b. DNA polymerase
c. DNA ligase
d. topoisomerase
e. primase
6. In solving the structure of DNA, Watson and Crick realized that
a. purines must base-pair with purines.
b. pyrimidines must base-pair with purines.
c. guanine must base-pair with guanine.
d. adenine must base-pair with guanine.
7. Which one of the following accurately reflects complementary base pairing in the DNA
molecule?
a. guanine-adenine
b. uracil-thymine
c. cytosine-hemanine
d. adenine-cytosine
e. thymine- adenine
8. What is the correct order of the following DNA replication events at one point on a DNA
molecule?
1. DNA unwinds as hydrogen bonds between bases break.
2. Ligases solidify connections on the lagging strand.
3. Polymerases move along the leading strand, adding complementary
nucleotides.
4. Proofreading by polymerases.
a.
b.
c.
d.
e.
4,1,2,3
4,2,1,3
1,2,3,4
1,3,4,2
1,4,2,3
9. Who are generally credited with discovering that the DNA molecule is constructed as a
double helix?
a. Singer and Nicolson
b. Hershey and Chase
c. Jacob and Monod
d. Watson and Crick
e. Davson and Danieli
10. In DNA, the weakest bonds are between
a. the sugar and the nitrogenous base.
b. two sugar molecules.
c. the phosphates and the sugar molecules.
d. two nitrogenous bases.
e. All of the above bonds are equally strong in DNA.
11. The two nucleotide strands of a DNA molecule are oriented __________ to one another.
a. antiparallel
b. perpendicular
c. counterclockwise
d. parallel
e. none of the above
12. Which one of the following describes a nucleotide most completely?
a. five-carbon sugar and a phosphate group only
b. four-carbon sugar and a purine
c. nitrogen base and a five-carbon sugar only
d. five-carbon sugar and a pyrimidine
e. nitrogen base, five-carbon sugar, and a phosphate group
13. The diagram below shows an origin of replication within a bacterial chromosome. From
the information provided, which of the numbered new strands are lagging strands
(composed of Okazaki fragments)?
a.
b.
c.
d.
e.
1 and 4
1 and 2
2 and 3
3 and 4
The answer cannot be determined from this information.
14. E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for
two generations (two rounds of DNA replication). DNA extracted from these cells is
centrifuged. What density distribution of DNA would you expect in this experiment?
a. one high density and one low density band
b. one intermediate density band
c. one high density and one intermediate density band
d. one low density and one intermediate density band
e. one low density band
15. A biochemist isolated and purified various molecules needed for DNA replication. When
she added some DNA, replication occurred, but the DNA formed was defective. Each DNA
molecule formed consisted of a normal DNA strand paired with numerous segments of
DNA a few hundred nucleotides long. What had she probably left out of the mixture?
a. primers
b. DNA polymerase
c. Okazaki fragments
d. nucleotides
e. ligase
16. What is the cause of the basic difference between the synthesis of the leading and the
lagging strands?
a. The origins of replication occur only at the 5’ end.
b. Helicase can only unwind the DNA molecule at the 5’end
c. DNA ligase works only from the 3’ to 5’ direction.
d. DNA polymerase can only add nucleotides to the 3’ end of a growing strand
(elongating in the 5’ to 3’ direction)
e. Polymerase can only work on one strand at a time
17. The primer that initiates the synthesis of a new DNA strand is made of
a. DNA nucleotides
b. RNA nucleotides
c. an Okazaki fragment
d. a thymine base
e. a protein
18. The energy that drives the replication of DNA replication is from
a. the hydrolysis of a nucleoside triphosphate
b. ADP
c. ligase binding Okazaki fragments
d. helicases unwinding DNA
e. none of these
19. The enzyme that makes the primer needed for DNA replication is called_______ and this
enzyme makes the _____ primer.
a. primase, DNA
b. primase, RNA
c. ligase, DNA
d. ligase, RNA
e. both a and c
20. After the removal of primers during DNA replication, gaps are found at the ends of the
newly formed DNA strands. This can cause the shortening of DNA and can lead to the
loss of genes. Special nucleotide sequences that help to prevent gene loss are called
a. ligase
b. telomeres
c. polymerase
d. RNA primers
e. none of these
21. DNA is an abbreviation for
a. deoxyribonucleic acid
b. deoxyriboflavin
c. dehydratedribo nuclease
d. dynein ribose acid
e. none of these
22. Which of the following is a difference between the leading and lagging strands during DNA
replication?
a. The leading strand only needs one primer, while the lagging strand needs a primer
for each Okazaki fragment.
b. Only the primer for the lagging strand gets replaced by DNA.
c. The primer for the leading strand is made up of DNA, while the primer for the lagging
strand is made up of RNA.
d. The leading strand elongates in a 5’ to 3’ direction, while the lagging strand
elongates in a 3’ to 5’ direction.
e. Helicase only unwinds the leading strand and not the lagging strand.
23. Which two bases are bonded by three hydrogen bonds?
a. A-C
b. C-G
c. A-U
d. G-T
e. A-T
24. Which enzyme helps to relieve the twisting strain on either side of the replication forks?
a. helicase
b. single-strand binding protein
c. DNA polymerase
d. nuclease
e. topoisomerase
25. Enzymes that help to keep the unwound strands of DNA apart (like spacers).
a. primase
b. single-strand binding protein
c. DNA polymerase
d. nuclease