Molecular Genetics

MULTIPLE CHOICE. This exam has 60 questions. All answers go on the SCANTRON provided. 
Choose the one alternative that best completes the statement or answers the question. 
1) The genetic material of all living organisms is
A) DNA. B) RNA. C) protein.
0 D) more than one answer is correct.

2) Who conducted experiments demonstrating that DNA is the genetic material of bacteriophages?
0
A) Hershey and Chase  B) Griffith C) Pauling D) Franklin E) Watson and Crick

3) Credit for the discovery of the three dimensional structure of DNA goes to
A) Hershey and Chase  B) Griffith C) Pauling D) Franklin 0 E) Watson and Crick

4) Deoxyribose is a
0
A) nucleotide  B) nucleic acid  C) sugar D) nitrogen base E) phosphate

5) Which of the following statements regarding DNA is false?
A) DNA is a nucleic acid.
B) One DNA molecule can include four different nucleotides in its structure.
C) DNA molecules have a sugar-phosphate backbone.
0
D) DNA uses the nitrogenous base uracil.
E) DNA uses the sugar deoxyribose.

6) The monomers of DNA and RNA are
A) amino acids.       B) nucleic acids.
-
C) monosaccharides. D) fatty acids. 0
E) nucleotides.

7) Which of the following can be found in a nucleotide of DNA?
A) deoxyribose B) phosphate   C) nitrogen base
0
D) all of the above

8) Which of the following is a nitrogen base found in DNA?
A) Adenine B) Thymine  C) Guanine D) Cytosine  0
E) all of the above

9) An understanding of DNA has important applications in understanding
A) the molecular genetic basis of life   B) Genetically modified (GM) foods
C) cancer 0
D) All of the above.

10) Using Chargaff’s rule as a model, we could calculate the percent of Guanine in the DNA of an
organism with 25% Adenine to be 
A) 4% 0
B) 25% C) 50% D) 75% E) 90%

11) Based on an understanding of the base composition observed in the DNA of different species,
Chargaff concluded that the percent composition of adenine is the same for all species. 
A) True 0B) False

12) As understood today, the DNA molecule
A) is a helix
B) has two polynucleotide chains, each with a sugar‐phosphate backbone
C) has the sugar deoxyribose
D) has the nitrogen bases A, T, G & C
0
E) all of the above are correct

-1-
 Molecular Genetics

13) The word “complimentary” as applied to DNA means
A) sugars and phosphates in the DNA are paired one for one
0
B) nitrogen base A pairs with T and G with C
C) nitrogen base A pairs with G and T with C
D) more than one answer is correct

14) The process of DNA synthesis could be described as
A) winding, pairing, joining B) joining, winding, pairing C) pairing, joining, pairing
0
D) unwinding, pairing and joining E) joining, pairing, unwinding

15) The word “semiconservative” as it pertains to DNA synthesis means

⑧
A) each new daughter DNA molecule contains one‐half the original parental DNA
B) the entire structure of the original parental DNA is conserved and not lost during DNA synthesis.
C) DNA synthesis occurs only when needed, so it is a semiconservative process.
D) DNA synthesis always recycles nucleotides so it is considered semiconservative.
E) all of these.

16) The flow of genetic information in all living organisms on Earth could be summarized as
A) Protein ‐> RNA ‐> DNA 0 B) DNA ‐> RNA ‐> Protein C) RNA ‐> DNA ‐> Protein
D) RNA ‐> Protein ‐> DNA E) Protein ‐> DNA ‐> RNA

17) The flow of genetic information in all living organisms on Earth could be summarized as consisting of
a set of instructions resulting in the synthesis of proteins. 

0
A)True    B) False

18) Translation is ___ using ___ as a coded information to determine the identity and arrangement of
amino acids in a protein. 
A) RNA synthesis:DNA B) DNA synthesis:RNA 0 C) protein synthesis:mRNA

19. The presence and action of proteins determine the phenotype of an organism.
0
A) True B) False

20) The directions for the kind and location of each amino acid in a polypeptide are indicated by a codon
consisting of ____ nucleotide(s) in an RNA molecule. 
0
A) 4   B) 1   C) 2   D) 3   E) 5

21) We would expect that a 15-nucleotide sequence in a messenger RNA molecule could direct the
production of a polypeptide that consists of _____ amino acids. 
A) 2   B) 4  0 C) 5  D) 15   E) 64

22) The genetic code has ___ different codons.
A) 2   B) 4  C) 5  0
D) 16   E) 64

23) One feature of the genetic code is that it is
A) redundant  B) unambiguous C) floppy O
D) universal (mostly)  E) all of these

-2-
24) Which of the following occurs when RNA polymerase attaches to the promoter region of DNA?
0
A) RNA synthesis is started.  B) RNA synthesis is ended. C) DNA synthesis is started.
D) Protein synthesis is started.  E) More than one answer is correct.

25) Which of the following options most accurately gives the sequence of events in translation?
A) peptide bond formation   codon recognition   translocation   termination
B) codon recognition   translocation   peptide bond formation   termination
0
C) codon recognition   peptide bond formation   elongation translocation   termination
D) peptide bond formation  translocation   codon recognition   termination
E) codon recognition   peptide bond formation   termination   translocation
-

ribosome codon Ert! 0l

26) If gene transcription consists of initiation, elongation and termination, what is being elongated?
A) DNA 0 B) RNA C) protein D) all of these

27) An essential feature of protein synthesis using mRNA and tRNA is codon‐anticodon pairing between
these two types of RNA. 
0
A) True B) False

28) What is the minimum number of codons required for a protein containing five amino acids?  (Don’t
worry about start or stop codons.)  
A) 4  0B) 5  C) 8  D) 15  E) none

29) What is the minimum number of RNA nucleotides required for a protein containing five amino acids?
(Don’t worry about start or stop codons.)  
A) 4  B) 5  C) 8  0 D) 15  E) none

30) What is the minimum number of DNA nucleotides required to make a messenger RNA molecule for a
protein containing five amino acids?  (Don’t worry about start or stop codons.)  
A) 4  B) 5  C) 8 0 D) 15  E) none

31) Let’s say a molecule of messenger RNA was just synthesized from eukaryotic DNA.  Let’s also
&
assume this mRNA primary transcript could be placed into a bacterial ribosome ready to do protein 
synthesis. What do you predict would happen? 
0A) a polypeptide would be produced, but it would not be a functional protein since introns were not
removed. 
B) the bacterial ribosome would first remove introns, then proceed to make a functional protein.
C) It is not possible for a bacterial ribosome to “read” eukaryotic mRNA under any circumstances.
D) a functional polypeptide/protein would be produced.

32) Let’s say a molecule of messenger RNA was just synthesized from prokaryotic DNA.  Let’s also
assume this mRNA transcript could be placed into a eukaryotic ribosome ready to do protein synthesis. 
What do you predict would happen? 
A) a polypeptide would be produced, but it would not be a functional protein since introns were not
removed.  X
B) the eukaryotic ribosome would first remove introns, then proceed to make a functional protein.
C) It is not possible for a eukaryotic ribosome to “read” prokaryotic mRNA under any circumstances.
0D) A functional polypeptide/protein would be produced.

-3-
 33) When DNA from two sources is combined into one single piece of DNA, it is known as
A) a DNA library. 0
B) recombinant DNA.  C) cloned DNA.   D) a vector. E) a plasmid.

34) Two enzymes central to the success of genetic engineering are
A) DNA polymerase and RNA polymerase 0
B) restriction endonucleases and ligase
C) protease and lipase D) exons and introns

35) Retroviruses such as HIV use _____ to convert information stored in their RNA to DNA.
A) a restriction enzyme B) a terminator enzyme C) RNA polymerase
D) DNA ligase
0
E) reverse transcriptase

36) Gene therapy can currently be considered

0
A) established & reliable.     B) impossible.     C) far off in the future.     D) promising.     E) cheap & easy.

37) The polymerase chain reaction relies upon heat‐resistant ______ isolated from bacteria living in hot
springs. 
A) plasmids  0
B) DNA polymerase molecules  C) mRNA D) phages E) restriction enzymes

38) Gel electrophoresis sorts DNA molecules on the basis of their
A) ability to bind to mRNA B) nucleotide sequence. C) solubility in the gel.
D) size. E) solubility in water.
0
39) Genetic engineering is to some extent the process of transferring DNA from one species to another
using appropriate enzymes. (This is true.) In other words, genetic engineering is like   
A) slash and burn B) show and tell   C) give and take
O
D) cut and paste

40) Approximately what percentage of human DNA is noncoding, i.e. not involved in RNA synthesis?
A) 37% B) 49% C) 99.9% D) 79% E) 98.5%

41) The coding regions of a gene (or mRNA molecule)  in a eukaryotic cell (the portions that are
expressed as polypeptide sequences) are called 
0
A) proto-oncogenes.  B) exons. C) introns. D) nucleosomes.

42) The development of colon cancer occurs slowly and is more prominent in the elderly than the
young. This is most likely because 
A) cancer cells have to wait until new blood vessels grow into the area, which takes much time.
B) cancer cells donʹt have mitochondria, so they grow slowly.
C) cancer cells suppress the growth of each other in a tissue.
0
D) most cancer mutations interfere with mitosis, so cell division occurs more slowly.
E) four or more somatic mutations must occur to give rise to the cancer and this takes time.

43) An application of genetic engineering in plant is
A) crops with enhanced nutritional value. B) pest‐resistant crops
C) herbicide resistant crops
⑧
D) all of these

44) A gene that has the potential to cause cancer when present in a single copy in a cell is called a(n)
A) enhancer gene. OB) proto‐oncogene.
-
C) carcinogen. D) oncogene.
-

normal Cancer cell

cell

-4-
 45) In order for cancer to occur DNA must first mutate. (This is true.) Mutation in DNA can occur because
of exposure to many carcinogens (like benzopyrene) in  
A) ultraviolet light. 0 B) tobacco. C) alcohol. D) salt. E) plutonium.

46) HIV is a
0
A) bacterium   B) virus C) prion D) protist

47) Which of the following is present in HIV?
A) RNA nucleic acid  ~ B) capsid
~
C) membrane-like envelope   O
D) all of these

48) Through integration, RNA of HIV can be inserted into the genomic DNA of the host cell.
0A) True
0B) False

49) Many viruses are said to be emerging. What does ʺemergingʺ mean?
A) Viruses from other animals can spread to humans  B) They can spread from isolated populations.
C) They can mutate rapidly.
⑦
D) All of these

50) An example of an emerging virus is
0A) HIV B) SARS C) West Nile  
0
D) All of these

51) A DNA “photocopying” process capable of making millions of copies of DNA in about an hour is
A) gel electrophoresis
0
B) PCR C) gene duplication D) gene expression

52) Some bacteria (like Staphylococcus) have developed a remarkable resistance to antibiotics, thus
making them especially harmful microorganisms. What feature of such bacteria give them the property of 
antibiotic resistance? 
0
A) They contain a plasmid with genes for antibiotic resistance.
B) They have a thick cell wall protecting them from the immune system.
C) They harbor viruses that can attack antibiotic drugs used against bacteria.
D) All of these.

53) Which of the following is a cause for mutation?
A) mistakes made in cells during DNA replication or recombination. B) high energy radiation.
C) mutagenic chemicals.  
O D) all of these
Mutagen
54) A mutation is any change in DNA.
0A) True B) False

55) Mutations known as substitutions, and deletions will affect the arrangement or order of __ in DNA.
0
A) nitrogen bases B) sugars C) phosphates   D) all of these

*56) A silent mutation will NOT affect
A) the nucleotide sequence in messenger RNA
B) the nucleotide sequence in DNA

8
C) the amino acid sequence translated from messenger RNA
D) none of these since a mutation will affect DNA, RNA and the protein amino acid sequence.

-5-
57) Which of the following permits a single gene to code for more than one polypeptide?
0
A) alternative RNA splicing
B) genetic differentiation
C) protein degradation
D) retention of different introns in the final version of the different mRNA strands
E) addition of different types of caps and tails to the final version of the mRNA strands

58) Sequences of DNA called ʺjumping genesʺ that can move around to different positions within the
genome of a single cell are also called 
A) inversions   B) jumpons O C) transposons D) operons

59) Ultraviolet light causes damage to DNA and forms
A) thymine-thymine dimers   B) adenine-guanine dimers
C) cytosine-thymine dimers   D) all of the above

60) Mutation in which type of gene can cause cancer?
A) Proto-oncogene B) Tumor-suppressor gene
0
C) Both A & B   D) None of these

-6-
 Multiple Choice Question Set I on

Molecular Biology: DNA synthesis (Replication)

1) In most organisms, DNA is a genetic material that stores the information template for
the synthesis of RNA and subsequently protein.
Name the processes a, b, c represented in the figure:

a) Replication
b) Transcription

C) Translation

Central Dogma of Molecular Biology

2) In some viruses, RNA serves as the storage of genetic materials and DNA is
synthesized from RNA by the enzyme known as:
a) DNA synthetase
b) DNA polymerase
0
c) Reverse transcriptase
d) DNA convertase

3) Which of the following process does not occur in prokaryotes?

a) Replication
0
b) Splicing bond
c) Translation X
Phosphodiester
d) Transcription
phosphate -

Sugar
backbone
)
4) Phosphodiester bond links two nucleotides together and maintains polarity which
refers to:
phosphate
&group of pentose of one nucleotide to 3' hydroxyl group of adjacent
a) the 5' hydroxyl
nucleotide through a phosphate group.
b) 5' end with a phosphate group and 3'end with hydroxyl are free.
 -

c) addition of new nucleotide occurs via attachment of 5' phosphate group of new
nucleotide to 3' phosphate group of an existing chain.
⑪d) All of the above

5) DNA helices exist in various forms.

Which of the following form is predominantly expressed in cells?
0
a) B- Helix
b) A-Helix
c) E-Helix
d) Z-Helix

6) Which one of the following statements is true regarding the DNA double-helical
structure?
a) The DNA double helix is coiled around a common axis known as the axis of symmetry
b) The hydrophilic deoxyribose-phosphate backbone of each chain is on the outside.
c) The hydrophobic nitrogen bases are stacked inside.
0
d) All of the Above

7) The spatial arrangement DNA helical structure creates a major and minor groove
which are important for:
a) kinking and bending of the helical structure
0
b) providing recognition and binding sites for various DNA binding proteins histone
ex)
c) All of Above
0
d) None of the Above

8) Aminoglycoside antibiotics such as kanamycin, tobramycin, neomycin are known

inhibitors of DNA synthesis. It contains a cyclitol ring linked to five or six-membered
sugars by glycosidic bonds.
These antibiotics are:

⑧a) Positively charged compound that to DNA and intercalates it.

b) Positively charged compound that binds to DNA polymerase activity.
c) Negatively charged compound to DNA and denatures it. DNAPoymeraseentire
ene

d) Negatively charged compound that binds to histones

9) The Chargaff rules state that the number of purines and pyrimidines are equal (A+G
= T + C) in any double-stranded DNA molecule. Watson and Crick later solved the
structure of DNA and nitrogen base pairings.
Which of the following base-pairing rule is true?
a) Adenine pairs with Guanine and Thymine pairs with Cytosine
0
b) Adenine pairs with Thymine and Guanine pairs with Cytosine
c) Adenine pairs with Cytosine and Guanine pairs with Thymine
 d) DNA base pairing is nonspecific

10) The DNA replication occurs in a semi-conservative manner which means:

a) Two daughter cells with one consisting of double-helical parent DNA, others have
newly synthesized DNA.
①b) Two daughter cells each consisting of one parental strand and one newly synthesized
DNA.
c) Two daughters cells each consisting of one-half parental and another half newly
synthesized DNA resulting from the crossover.
d) None of the above

11) Which of the following are the characteristic feature of DNA replication?
a) DNA replication is template-directed
b) DNA replication requires short RNA primers
c) DNA replication is a highly accurate process
0
d) All of the Above

12) In prokaryotes, DNA replication begins at a single site that is rich in AT nucleotide
sequence, where two strands unwind and separate.
This ATP dependent process is catalyzed by a protein known
as..................................?
a) DnaA protein
b) Single-strand binding protein
c) DNA polymerase
⑫
d) Topoisomerase

13) The short strand of .......................... primer is required for the replication of DNA:
a) DNA
0
b) RNA
c) Histone
d) hnRNA

14) As the two strands of the double helix are separated, the positive supercoiling
interferes with the further unwinding of DNA.
Which of the following enzyme makes a break in a strand of DNA to release
the supercoiling and facilitate the replication to occur?
a) DnaA protein
b) Single-strand binding protein
c) DNA polymerase
0d) Topoisomerase
 15) Which of the following enzyme has a unique ability to introduce positive and
negative supercoiling of the DNA and it is the target for antibacterial agents such as
ciprofloxacin/quinolones?
a) DnaA protein
b) DNA helicase
for regulating the
0 responsible
bacteria that
c) DNA gyrase in is
type 2 topoisomerase enzyme

d) DNA polymerase Supercorling of DNA.

16) DNA replication is bidirectional and anti-parallel.

Which of the statement is FALSE regarding DNA replication?
a) The DNA synthesis i.e. addition of nucleotide occurs from 5'-3' position
b) The DNA synthesis is semi-continuous with continuous leading strand and
discontinuous lagging strand.
c) The synthesis of leading and lagging strands occurs simultaneously
d) None of the Above
0
17) The DNA polymerase is a template-directed enzyme that synthesizes a new
complementary strand from a parent strand but it requires the existing short nucleotide
sequence for its elongation.
Which of the following enzyme is required for the synthesis of this primer?
0
a) Primase/RNA polymerase
b) RNA synthase
c) DNA synthase
d) Helicase

*
18) DNA polymerase III holoenzyme possesses:
a) polymerase activity only
b) 3’→ 5’ endonuclease activity
c) 3’→ 5’ exonuclease activity and polymerase activities
d) 5’→ 3’ exonuclease activity

19) Which of the following statement is true regarding an enzyme DNA polymerase that
catalyzes the elongation of complementary DNA strand?
a) DNA polymerase III is a highly processive enzyme.
b) DNA polymerase III possesses 5'-3' polymerase activity required for elongation.
c) DNA polymerase III possesses 3'-5' exonuclease activity important for maintaining
fidelity
0d) All of the above

20) In prokaryotes, the RNA primer from the lagging strand is removed and replaced by
the DNA sequence.
This process is catalyzed by an enzyme ..................................................which possess
5'-3' exonuclease activity and 5'-3' polymerase activity.
a) DNA polymerase I
0
b) DNA polymerase II
c) DNA polymerase III
d) DNA polymerase IV

21) In eukaryotes, DNA polymerase alpha is a multi-subunit enzyme with different

functions. They include..........................................................?
a) Elongation of the leading strand
0
b) 3'-5' exonuclease activity
c) Initiation and synthesis of RNA primer
d) High processivity

22)-In eukaryotes, which of the following DNA polymerase is highly processive and
required
- for the elongation phase of DNA replication?
a) Pol alpha
b) Pol delta
c) Pol gamma
d) Pol beta

23) In eukaryotes, which of the following DNA polymerase is required for mitochondrial
DNA
- replication?
a) Pol alpha
b) Pol beta
c) Pol gamma
d) Pol delta

⑧
24) Telomeres are the repetitive sequence of T's and G's that are present in the
eukaryotes to protect the random cleavage from nucleases. These telomeres are
synthesized by the enzyme telomerase.
Which of the following are the properties of enzyme telomerase?
a) Telomerase is a reverse transcriptase enzyme
b) Telomerase consist of an RNA sequence that serves as a template
c) After completion of each cycle, telomerase translocates to 3'end of DNA to synthesize
repetitive sequence.
d) All of the above