GENETIC ENGINEERING HW
AP BIOLOGY
DR WEINER
Multiple Choice (3 pt)
Questions 1-4 refer to the following experiment:
Four vials were set up to investigate bacterial transformation. Vials 1 and 2 each contained E. coli
bacteria that had been made competent and had been mixed with plasmid containing the gene for
ampicillin resistance (pAMP). Vials 3 and 4 both contained E. coli that had also been made competent
but had not been mixed with plasmid. Each vial of bacteria were poured onto a nutrient agar plate.
Vials 1 and 3 were poured onto plates that contained the antibiotic ampicillin. Vials 2 and 4 were
poured onto plates that did not contain ampicillin.
The figure shows what the plates looked like. The shaded plates indicate extensive growth, and
the dots represent individual colonies.
from vial1
1
from vial 2
2
from vial 3
3
from vial 4
4
1. Plates that have only ampicillin-resistent bacteria growing on them include which of the
following?
a. Plate 1 only
b. Plate 2 only
c. Plate 3 only
d. Plate 1 and 3
2. Which f the following explains why there was no growth on plate 3?
a. The heat shock technique to make the E. coli competent killed the bacteria
b. Those bacteria were inhibited from growing by the nutrient in the agar
c. Those bacteria were not transformed
d. The bacteria died due to a short life span
3. Which of the following explains why there were fewer colonies on plate 1 than on plate 2?
a. The bacteria on plate 2 did not transform
b. There was no antibiotic on plate 2 that would have restricted the growth of the bacteria
c. The transformation of bacteria on plate 2 was more successful
d. The bacteria on plates 1 and 2 were not taken from the same culture
4. In a variant of this experiment, the plasmid contained GFP (green fluorescent protein) in
addition to ampicillin resistance. Which of the following plates would have the highest
percentage of bacteria that would fluoresce?
a. Plate 1 only
b. Plate 2 only
c. Plate 3 only
d. Plate 4 only
Questions 5 and 6 refer to the following scenario: Four decades after the end of Vietnam War, the
remains of an Air Force pilot were discovered and returned to the United States. A search for Air Force
records identified three families to which the remains might possibly belong. Each of the families had
a surviving twin of a missing service member. The following STR profiles were obtained from the
pilot’s remains and the surviving twins from the three families.
Air force
pilot
Family 1 Family 2 Family 3
1
2
3
4
5
6
7
8
9
10
11
12
13
5. In order to match the pilot’s remains to the correct family
a. The majority of the STR bands must match
b. Each of the 13 STR bands must match
c. The bands for only a few bands should match
d. It is impossible to determine without the parent’s DNA
6. Based on the STR analysis shown, does the missing pilot belong to any of these three families?
a. No, none of the families match
b. Yes, family 1 matches
c. Yes, family 2 matches
d. Yes, family 3 matches
Questions 7 and 8 refer to the following gel, which was produced from four samples of a radioactively
labeled strand of DNA that were cut with one type of restriction enzyme. The samples were separated
by gel electrophoresis. Answer the questions on the basis of the bands visualized below
Samples
1
2
3
4
7. The DNA fragments in the gel were separated when an electric field was applied across the gel
and they migrated at different speeds. The different migration speed of the different DNA
fragments was due to the
a. Amount of radioactivity in the samples
b. Degree to which the samples were negatively charged
c. Degree to which the DNA was positively charged
d. Size of the fragments within the samples
8. Which of the following is true about the DNA samples that were loaded on the gel?
a. The DNA strand of sample 2 was originally the longest
b. The DNA strand of sample 4 was originally the shortest
c. Samples 2 and 4 are the same DNA sample
d. Sample 2 was cut at more restriction sites than was sample 4
9. Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of
genomic DNA that has been cut with restriction enzyme X. The gene you want to insert has
sites on both ends for cutting by restriction enzyme Y. You have a plasmid that has a single
restriction site for Y but not for X. Your strategy should be to
a. Cut the plasmid with restriction X and insert the fragments cut with restriction enzyme
X into it
b. Cut the fragment again with restriction enzyme Y and insert the fragment into the
plasmid cut with restriction enzyme Y
c. Cut the plasmid with restriction enzyme Y and insert the fragment into it
d. Insert a fragment into the plasmid to take up the fragment cut with restriction enzyme X
10. A principal problem with inserting an unmodified mammalian gene into a BAC (bacterial
artificial chromosome that can accept large fragments of DNA for cloning), and then getting
the gene to be expressed in bacteria, is that
a. Prokaryotes use a different genetic code than eukaryotes
b. Bacteria can only translated polycistronic mRNAs
c. Bacteria cannot remove mammalian introns
d. Mammalian genes are incompatible with bacteria
11. In order to be able to express a mammalian gene in bacteria, which of the following shold be
done?
a. Use RNA polymerase to transcribe the gene first
b. Cut the gene into shorter fragments first
c. Use reverse transcriptase to reconstruct the gene from its mRNA
d. Use DNA polymerase to reconstruct the gene from its polypeptide product
Questions 12-14 refer to the following:
A eukaryotic gene has “sticky ends” produced by the restriction enzyme Eco RI. The gene is
added to a mixture containing Eco RI and a bacterial plasmid that carries 2 genes conferring resistance
to ampicillin and tetracycline. The plasmid has one restriction site for Eco RI in the middle of the
tetracycline resistance gene. This mixture is incubated for several hours, exposed to DNA ligase, and
then added to bacteria growing in nutrient broth. The bacteria are allowed to grow overnight and are
streaked on a plate that produces isolated colonies that are clones of the original. Samples of these
colonies are then grown in 4 different media: nutrient broth plus ampicillin, nutrient broth plus
tetracycline, nutrient broth with both ampicillin and tetracycline, nutrient broth with no antibiotics.
12. Bacteria that contain the plasmid , but not the eukaryotic gene, would grow
a. In the broth with ampicillin but not the broth with tetracycline
b. Only in the broth that has both antibiotics
c. In all 4 broths
d. In only the broth without any antibiotics
13. Bacteria containing the plasmid into which the eukaryotic gene was cloned into would grow
a. In nutrient broth with tetracycline
b. In nutrient broth with ampicillin
c. In nutrient broth with ampicillin and tetracycline
d. In broth with ampicillin and broth with no antibiotics
14. Bacteria that did not take up any plasmid would grow in which media?
a. Nutrient broth with no antibiotics
b. Nutrient broth with only one of the two antibiotics
c. Nutrient broth with both antibiotics
d. All of the broths
Questions 15 and 16 refer to an experiment that was performed to separate DNA fragments frm three
samples radioactively labeled with 32P. the fragments were then separated using gel electrophoresis.
The visualized bands are depicted below:
15. When the electric field was applied, the fragments of DNA in each of the three samples
migrated to different locations along the gel because
a. The fragments differed in their level of radioactivity
b. The fragment differed in their charges- some were negatively charged and xome were
positively charged
c. The fragments differed in their solubility
d. The fragments differed in their size
16. How many sites on DNA were cut by the particular restriction enzyme used in sample 1, the
leftmost sample?
a. 8
b. 7
c. 6
d. 5
Questions 17-19
10 kb
refer to the diagram below
3 kb
1
25 kb
2
35 kb
1
17. Restiction enzymes 1 and 2 can cut DNA at the locations shown. If the DNA is cut ONLY by
enzyme 1, which of the following fragment sizes would be expected?
a.
b.
c.
d.
e.
10 and 35 kb
25 and 35 kb
35 kb
10, 28, 35 kb
73 kb
18. If a mutation took place in the DNA sequence for restriction enzyme 1, which of the following
is a likely consequence?
a.
b.
c.
d.
e.
Enzyme 1 will cut at site 2
The fragment lengths will increase in size
The enzyme will recognize the restriction sites and cut anyway
The enzyme will recognize different sites
The enzyme will require a different pH to digest the DNA
19. If the DNA molecule was cut by both enzymes and run on a gel, which well would represent
the migration of the fragments produced?
A
80
70
60
50
40
30
20
10
B
C
D
E
Short Answer
1. Briefly describe the importance of the following in an transformation experiment (10 pt):
a. Making the bacteria competent
b. Using a plasmid with a marker gene like antibiotic resistance or fluorescence
c. Restriction enzymes and DNA ligase
d. The multiple cloning site
e. A functional promoter
2. What are genomic and cDNA libraries and indicate the uses for each (5 pt)
3. You have a plasmid with a bacterial promoter in it and you want to clone a human gene from a
cDNA library to make the protein product. In front of the promoter is the multiple cloning site.
The MCS has an Eco R1 site next to the promoter and a Hind III site farther down. In your
cDNA there is an Eco R1 site on both the 5’ and 3’ ends. And a Hind III site on the 3’ end.
Which enzyme(s) should you use to clone your gene into the plasmid in order to be able to
express the gene from the promoter? (5 pt)
4. Explain the importance of the following in gel electrophoresis (10 pt):
a. Tracking dye
b. Current
c. The % agarose in the gel
d. Staining dye like ethidium bromide
5. Briefly describe the 3 stages of PCR and their importance (10 pt)