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May 2012 DNA Structure and Molecular Biology

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 
Why does a DNA strand grow only in the 5' to 3' direction?
a.
because mRNA can only read a DNA molecule in the 5' to 3' direction
b.
because DNA polymerases can only add nucleotides to the 3' end of the growing molecule
c.
because DNA polymerases can only add nucleotides to the 5' end of the growing molecule
d.
None of the choices are correct.
 

 2. 
We would expect that a 15-nucleotide sequence will direct the production of a polypeptide that consists of
a.
7 amino acids.
b.
3 amino acids.
c.
5 amino acids.
d.
2 amino acids.
e.
15 amino acids.
 

 3. 
The signal that marks the end of a gene and causes transcription to stop is
a.
methionine.
b.
a terminator.
c.
RNA ligase.
d.
RNA polymerase.
e.
reverse transcriptase.
 
 
The following is the beginning sequence of a gene that is transcribed onto mRNA (you can assume that the entire sequence here is transcribed).  The sequence shown is from the strand that is transcribed.
G A C C A T A C A A A C A C T T G



Based on your understanding of the processes involved in gene expression, determine the sequence of amino acids that will be coded by the sequence above.  You must take into consideration the regulatory elements of translation.  The genetic code is provided for your convenience.

nar001-1.jpg
 

 4. 
What is the amino acid sequence coded by the DNA sequence?
a.
Leu-Val-Cys-Leu
b.
Leu-Val-Cys-Leu-Asn
c.
Leu-Val-Val-Cys-Leu
d.
Met-Phe-Val-Asn
e.
Met-Phe-Val-Asn-Leu-Val
 

 5. 
A mutation occurs changing a single DNA nucleotide in the sequence. Which of the following is true?
a.
This is an example of a substitution mutation.
b.
This is an example of a frameshift mutation.
c.
It is possible that the resulting amino acid sequence is unchanged.
d.
The entire amino acid sequence of the protein is always affected.
e.
Both (a) and (c) are true
 
 
Answer the questions based on your understanding of the following diagram.  Numbers 1, 2, and 5 point at separate molecules.  Numbers 3 and 4 point at regions of molecule 2.

nar002-1.jpg
 

 6. 
The enzyme labeled 1 is:
a.
RNA polymerase.
b.
DNA polymerase.
c.
capable of adding new nucleotides to a growing nucleic acid.
d.
Both (a) and (c) are correct.
e.
Both (b) and (c) are correct.
 

 7. 
Which of the following is RNA polymerase?
a.
1
b.
2
c.
3
d.
4
e.
5
 
 
Answer the questions based on the following diagram.  All labels point at the entire “object” except for 4 and 6.  4 and 6 point at a specific part of the larger object.

nar003-1.jpg
 

 8. 
The diagram represents which of the following processes?
a.
Replication.
b.
Transcription.
c.
Translation.
d.
Protein expression.
e.
Cellular respiration.
 

 9. 
In eukaryotes, this process occurs in the:
a.
nucleus.
b.
cytoplasm.
c.
vacuole.
d.
golgi apparatus (golgi body).
e.
transport vesicle.
 

 10. 
Which of the following statements is false regarding the “anticodon”?
a.
It is associated with the structure labeled “4”.
b.
It is complementary to corresponding sequences on the structure labeled “5”.
c.
It is a sequence of nucleotides.
d.
It is a sequence of amino acids.
e.
Both (b) and (d) are false.
 
 
Answer the following questions based on the diagram below.
nar004-1.jpg
 

 11. 
Which of the following statements is true about gene expression?
a.
“6” is a chemical modification to mRNA occurring after transcription.
b.
“7” is a molecule that is transcribed from DNA.
c.
“8” can be found bound to the rough E.R.
d.
Both (a) and (b) are true.
e.
All statements are true.
 

 12. 
Which of the following statements describe processes in the diagram that are exclusive to eukaryotes?
a.
Splicing of intron sequences from the mRNA.
b.
Addition of cap and tails to mRNA.
c.
The transfer of amino acids to the ribosome by tRNA.
d.
Both (a) and (b).
e.
All of the above.
 
 
nar005-1.jpg
 

 13. 
The diagram above shows two polynucleotides held together by the interaction of the nitrogenous bases. Which of the choices specifies this interaction?
a.
1
b.
2
c.
3
d.
4
e.
5 and 4
 

 14. 
The diagram of the molecule shown above is oriented in an “anti-parallel” manner. Which of the following correctly specifies the orientation?
a.
3- specifies the hydrogen bonds
b.
2- specifies the 5- end of the molecule
c.
1-specifies the 3’ end of the molecule
d.
4- specifies a nucleotide
e.
both b and c
 
 
The following image represents a prokaryotic gene. The highlighted regions corresponds to different components of the gene including- promoter, coding region, and terminator. Use the image to answer the following questions.


nar006-1.jpg
 

 15. 
Which arrow highlights where transcription begins?
a.
2
b.
3
c.
4
d.
5
e.
6
 

 16. 
The mRNA transcript will be generated from copying DNA into RNA between which arrows?
a.
1 to 7
b.
2 to 7
c.
3 to 7
d.
6 to 4
e.
3 to 5
 

 17. 
Which of the following arrows corresponds to NON-CODING DNA?
a.
1, 2, 3, 6
b.
1, 2, 5
c.
1, 4, 6
d.
4 ,6
e.
4, 6, 7
 

 18. 
Which of the following choices best corresponds to the ORF of the DNA?
a.
between 1 and 2
b.
between 1 and 7
c.
between 2 and 7
d.
between 6 and 4
e.
between 6 and 5
 
 
The diagram below traces the process of creating a double stranded DNA molecule (#8) from a eukaryotic gene (human insulin). Reminder: eukaryotic genes cannot be directly spliced into prokaryotic genomes due to the presence of intron and exons within  the eukaryotic genes.
nar007-1.jpg
 

 19. 
The actual start codon AUG would be found in ---.
a.
the insulin gene
b.
4
c.
5
d.
8
e.
all of the above
 

 20. 
The region highlighted by “1” is  ---.
a.
replication
b.
transcription
c.
translation
d.
alternative splicing
e.
 UTR
 

 21. 
Which best matches the number to the correct function?
a.
1.......transcription
b.
2.......mRNA editing
c.
3.......reverse transcription
d.
4.......exon
e.
all of the above are true
 

 22. 
The process of DNA replication
a.
makes molecules of RNA as an end product.
b.
involves a single enzyme; DNA polymerase.
c.
produces two molecules, each of which is half-new and half-old.
d.
occurs only in eukaryotic cells.
e.
None of the above are true.
 

 23. 
DNA polymerase
a.
recognizes the promoter to start replication.
b.
adds new nucleotides to a strand.
c.
is active during both DNA replication and transcription.
d.
is active during mitosis.
e.
does all of the above.
 

 24. 
DNA ligase
a.
is only active on one side of the replication bubble.
b.
functions to create hydrogen bonds between complementary bases.
c.
adds primers to single stranded DNA.
d.
forms covalent bonds.
e.
None of the above.
 
 
The following diagram shows one end of a replication bubble.  Labels “1” through “6” point at separate objects.  “7” and “8” point at the two separate strands of the molecule.

Answer the following questions based on your understanding of replication and this diagram.
nar008-1.jpg
 

 25. 
Which statement is true?
a.
The enzyme labeled “1” breaks covalent bonds to separate the double stranded DNA.
b.
The enzyme labeled “2” adds DNA nucleotides to the 5’ end of the new, extending strand of DNA.
c.
“4” is the promoter sequence.
d.
“7” points at the 3’ end of DNA.
e.
The enzyme labeled “3” creates RNA primers necessary for DNA polymerase.
 

 26. 
The two, newly synthesized, DNA molecules at the replication fork can be described as the “leading” and “lagging” strands.  Which of the following statements is false?
a.
The top strand is the leading strand.
b.
The leading strand must be created in multiple fragments that are later connected by the enzyme ligase.
c.
Starting at the origin of replication, the leading strand requires a single RNA primer.
d.
Both (a) and (b) are false.
e.
Both (b) and (c) are false.
 

 27. 
When the process shown here is not completed with a 100% accuracy, the result can lead to
a.
denaturation.
b.
a covalent bond.
c.
plasmolysis.
d.
a mutation
e.
facilitated diffusion.
 

 28. 
This process can be described as being
a.
stabilizing.
b.
semi-conservative.
c.
disruptive.
d.
radiating.
e.
tertiary.
 
 
The following diagram shows a sequence of a reaction.  The numbers 1through 4 identify different parts of the overall structure.
nar009-1.jpg
 

 29. 
This reaction is facilitated by which structure in the cell?
a.
DNA polymerase
b.
RNA polymerase
c.
Ribosome
d.
Nucleus
e.
Hydrolase
 

 30. 
Which one of the following is false?
a.
One DNA molecule can include four different nucleotides in its structure.
b.
DNA uses the sugar deoxyribose.
c.
DNA molecules have a sugar-phosphate backbone.
d.
DNA uses the nitrogenous base uracil.
e.
DNA is a nucleic acid.
 

 31. 
Multiple origins of replication on the DNA molecules of eukaryotic cells serve to
a.
assure the correct orientation of the two strands in the newly growing double helix.
b.
create multiple copies of the DNA molecule at the same time.
c.
shorten the time necessary for DNA replication.
d.
reduce the number of "bubbles" that occur in the DNA molecule during replication.
e.
remove errors in DNA replication.
 

 32. 
Which one of the following sequences best describes the flow of information when a gene directs the synthesis of a cellular component?
a.
protein --> RNA --> DNA
b.
DNA --> amino acid --> RNA --> protein
c.
RNA --> DNA --> RNA --> protein
d.
DNA --> RNA --> protein
e.
DNA --> tRNA --> mRNA --> protein
 

 33. 
The transfer of genetic information from DNA to RNA is called
a.
transcription.
b.
promotion.
c.
elongation.
d.
translation.
e.
initiation.
 

 34. 
Translation consists of which of the following?
a.
the conversion of genetic information from the language of nucleic acids to the language of proteins
b.
the conversion of genetic information from DNA nucleotides into RNA nucleotides
c.
DNA replication
d.
the addition of nucleotides to a DNA template
e.
the conversion of genetic information from the language of proteins to the language of enzymes
 

 35. 
Which one of the following is not a function of tRNA?
a.
joining to only one specific type of amino acid
b.
recognizing the appropriate codons in mRNA
c.
helping to translate codons into amino acids
d.
transferring nucleotides to rRNA
e.
All  of the choices are functions of tRNA.
 



 
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