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Test 4: Gene Expression & Regulation

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

 1. 
Which one of the following statements is false? (This is question is based on our discussion of the influenza virus that caused ‘swine flu’).
a.
Viruses can enter a host cell when the protein molecules on the outside of the virus fit into receptor molecules on the outside of the cell.
b.
The genetic material for viruses can be either DNA or RNA.
c.
A virus is a unicelluar organism that is capable of dividing on its own.
d.
Viruses are specific to which hosts they infect.
e.
The host cell provides most of the tools and raw materials for viral multiplication.
 

 2. 
Which one of the following is false?
a.
DNA molecules have a sugar-phosphate backbone.
b.
DNA uses the sugar deoxyribose.
c.
DNA uses the nitrogenous base uracil.
d.
DNA is a nucleic acid.
e.
One DNA molecule can include four different nucleotides in its structure.
 

 3. 
How would the shape of a DNA molecule change if adenine paired with guanine and cytosine paired with thymine? The DNA molecule would
a.
be shorter.
b.
have regions where no base-pairing would occur.
c.
have irregular widths along its length.
d.
be longer.
e.
be circular.
 

 4. 
When one DNA molecule is copied to make two DNA molecules, the new DNA contains
a.
75% of the parent DNA.
b.
50% of the parent DNA.
c.
none of the parent DNA.
d.
100% of the parent DNA.
e.
25% of the parent DNA.
 

 5. 
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.
remove errors in DNA replication.
c.
shorten the time necessary for DNA replication.
d.
reduce the number of "bubbles" that occur in the DNA molecule during replication.
e.
create multiple copies of the DNA molecule at the same time.
 

 6. 
What is the relationship between mRNA and the non-template DNA strand?
a.
they are complementary to each other
b.
they are exactly the same in nucleotide sequence
c.
they share the same base pair sequence, except uracil takes the place of thymine in RNA.
d.
there is no relationship
 

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

 8. 
A base substitution mutation in a gene sometimes does not result in a different protein.  Which of the following factors could account for this?
a.
the mutation affects only the sequence of the protein's amino acids, so the protein stays the same
b.
the fact that such mutations are usually accompanied by a complementary deletion
c.
the rarity of such mutations
d.
some amino acids are produced from more than one codon
e.
a correcting mechanism that is part of the mRNA molecule
 

 9. 
Where do transcription and translation occur in prokaryotic cells?
a.
in the cytoplasm
b.
in chromatophores
c.
in the nucleus
d.
in the cell wall
e.
on the plasma membrane
 

 10. 
Which one of the following does not happen to eukaryotic RNA?
a.
A small cap of extra nucleotides is added to one end of the RNA.
b.
The completed RNA molecule is exported out of the nucleus.
c.
A long tail of adenine (A) nucleotides is added to the other end of the RNA.
d.
Introns are added to the RNA.
e.
Exons are spliced together.
 

 11. 
Translation consists of which of the following?
a.
DNA replication
b.
the addition of nucleotides to a DNA template
c.
the conversion of genetic information from DNA nucleotides into RNA nucleotides
d.
the conversion of genetic information from the language of nucleic acids to the language of proteins
e.
the conversion of genetic information from the language of proteins to the language of enzymes
 

 12. 
Consider the following sentence: "The dog did not eat." Which one of the following variations of this sentence is most like a reading frame mutation?
a.
The dod idn ote at.
b.
The did dog not eat.
c.
The did not eat.
d.
The dog dog did not eat.
e.
The dog did dog did not eat.
 

 13. 
Which of the following is the enzyme that viruses, such as HIV, use to synthesize DNA from an RNA template?
a.
reverse transcriptase
b.
ligase
c.
RNA polymerase
d.
terminator enzyme
e.
None of the choices are correct.
 

 14. 
Transformation
a.
requires DNA polymerase.
b.
occurs when a bacterium acquires DNA from the surrounding environment.
c.
occurs when a virus transfers bacterial DNA from one bacterium to another.
d.
is the direct transfer of DNA from one bacterium to another.
e.
is the result of mutation.
 

 15. 
In a prokaryote, a group of genes with related functions, along with their associated control sequences, defines
a.
a gene.
b.
an operator.
c.
a locus.
d.
an operon.
e.
a chromosome.
 

 16. 
The genes for the enzymes of glycolysis
a.
and the genes for all specialized proteins are expressed in all embryonic cells.
b.
are inactive in all metabolizing cells but the genes for specialized proteins are expressed in all cell types.
c.
and the genes for specialized proteins are expressed in all nonembryonic cell types.
d.
and the genes for all specialized proteins are expressed in all metabolizing cells.
e.
are active in all metabolizing cells but the genes for specialized proteins are expressed only in particular cell types.
 

 17. 
Most differentiated cells retain
a.
only a tiny fraction of their original set of genes but can regenerate lost genes as needed.
b.
only a tiny fraction of their original set of genes.
c.
a complete set of their genes and retain the ability to express specific genes under certain circumstances.
d.
a complete set of their genes but lose the ability to express most of those genes.
e.
None of the choices are correct.
 

 18. 
Which of the following permits a single gene to code for more than one polypeptide?
a.
protein degradation
b.
addition of different types of caps and tails to the final version of the mRNA strands
c.
alternative RNA splicing
d.
genetic differentiation
e.
retention of different introns in the final version of the different mRNA strands
 
 
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.
nar001-1.jpg
 

 19. 
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.
 

 20. 
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.
 
 
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 that of the template strand.
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.
nar002-1.jpg
 

 21. 
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
 

 22. 
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.
nar003-1.jpg
 

 23. 
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.
 

 24. 
Which statement is false regarding the region labeled 3.
a.
It is the promoter.
b.
It is the start codon.
c.
The sequence here is NOT “written” onto the molecule labeled 5.
d.
It is a sequence of DNA.
e.
Both (b) and (d) are false.
 

 25. 
Which of the following statements is true?
a.
The molecule “5” is later translated by the ribosome.
b.
In eukaryotes, this process occurs in the cytoplasm.
c.
The enzyme “1” recognizes the start codon.
d.
The enzyme “1” recognizes the stop codon.
e.
The molecule “2” is RNA.
 
 
Answer the following questions based on the diagram below.
nar004-1.jpg
 

 26. 
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.
 

 27. 
Which of the following statements describe processes in the diagram that are exclusive to eukaryotes?
a.
Splicing out 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.
 

 28. 
Which of the following statements is true?
a.
The enzyme labeled 2 makes new DNA.
b.
The molecule marked 3 is a chain of amino acids.
c.
The molecule marked 7 is a chain of nucleotides.
d.
The structure marked 8 is made up of both amino acids and nucleotides
e.
None of the above statements are true.
 

 29. 
The entire process ensures which of the following?
a.
The genetic code of DNA is conserved and unaltered even after gene expression.
b.
The genetic code of DNA can be used repeatedly without “using up” DNA.
c.
The ribosome and tRNA converts the sequence of nucleotides copied from DNA to determine a specific sequence of amino acids.
d.
Proteins are created using the genetic code of DNA.
e.
All of the above.
 
 
The following diagram represents the Lac operon in two different environments.  Answer the following questions based on this diagram.
nar005-1.jpg
 

 30. 
RNA polymerase must bind:
a.
3
b.
4
c.
5
d.
7
e.
Both (4) and (7)
 

 31. 
The advantage of the Lac operon is:
a.
The expression of genes can be regulated by environmental signals.
b.
Proteins not necessary in a specific environment will not be expressed.
c.
Human cells do not have to make all proteins encoded by its DNA.
d.
Both (a) and (b).
e.
All of the above.
 

 32. 
The repressor protein can bind:
a.
3 and 2
b.
5 and 6
c.
4 and 9
d.
5 and 9
e.
6 and 9
 

 33. 
The molecule labeled (8) is:
a.
Lactose
b.
Ribosome
c.
Helicase
d.
DNA polymerase
e.
RNA polymerase
 

 34. 
The molecules labeled (10) are used by the bacteria to:
a.
Break down lactose to generate ATP through cellular respiration.
b.
Bind the operator to inhibit transcription.
c.
Activate RNA polymerase by breaking down the repressor molecule.
d.
Begin DNA replication.
e.
Create additional sugars for the bacteria.
 
 
The following plasmid map shows the three genes on the plasmid pBIO.  The GFP gene and ampicillin resistance gene (AMPR) are regulated by a promoter that is always “on”.  Therefore, the genes are always expressed once in a cell.  The kanamycin resistance gene (KANR) is regulated by the Lac operon.  Kanamycin is another antibiotic that prevents the grow of bacteria.

Plates labeled with “Amp” and “Kan” contain the corresponding antibiotics.  The plate labeled with “lactose” contains the sugar lactose.  A bacterial culture is transformed with pBIO and successfully transformed cells are plated on all four plates shown below.

Answer the questions based on your understanding of transformation, regulation by the Lac operon, and gene expression.
nar006-1.jpg
 

 35. 
You transform bacteria (E.coli) with the plasmid pBIO.  The successfully transformed cells are plated onto the four plates above.  On which plate will you not see any growth?
a.
LB
b.
LB/Amp
c.
LB/Amp/Kan
d.
LB/Amp/Kan/lactose
e.
All plates will have some growth
 

 36. 
Which of the following is not an observation you will make?
a.
The LB plate will show lawn growth because all plated bacteria, including those that did not take up a plasmid, will be able to grow.
b.
The LB/Amp plate will show colony growth.  Each colony represents a single bacterium that took up the plasmid pBIO and grew into millions of cells during incubation.
c.
All colonies on the LB/Amp/Kan/Lactose plate will GLOW because GFP is expressed.
d.
The colonies on the LB/Amp plate will GLOW.
e.
When untransformed E.coli is plated onto LB/Amp/Kan/lactose, you will see lawn growth because lactose will help make bacteria resistant to the antibiotics.
 



 
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