Unit 3 Review • MHR 32729.Prepare a diagram illustrating the elongation
cycle of translation. Include a brief written
description of each step in the cycle. How does
a stop codon work to end the cycle?
30.Given the fact that complexes known as
spliceosomes are found in eukaryotic cells,
answer the following questions.
(a)Where in a eukaryotic cell would you
expect to find spliceosomes? Explain.
(b)You are able to remove all the spliceosomes
from a living eukaryotic cell. What effect
would you expect this to have on the
metabolism of the cell? Explain.
(c)You are able to insert spliceosomes into a
living bacterial cell. What effect would you
expect this to have on the metabolism of
the cell? Explain.
31.Explain how the action of the trypoperon
helps a bacterial cell conserve energy and
resources. Why is the trypoperon considered a
repressible operon?
32.An E. colicell undergoes a frameshift mutation
in the gene that codes for lacrepressor protein.
(a)Would you expect this mutation to affect
the lacgenes? Explain.
(b)Assume this mutation makes the repressor
protein non-functional. In what way would
this cell react differently than a normal
E. colicell to a sudden increase in the
concentration of lactose in its environment?
33.A plant cell is subjected to a high level of UV
radiation. What effect could this exposure
produce in the DNA of this cell? What might
the effect be on its daughter cells?
34.Create a labelled diagram that illustrates the
steps in excision repair.
35.Describe two different methods that can be
used to amplify a sample of DNA.
36.A researcher wishes to create a transgenic
banana that will stay firm and yellow longer
than a wild banana does. As a potential aid,
she has isolated a strain of bacteria that
secretes a protein that slows the ripening
process in bananas.
(a)What main steps might she follow to
develop the new strain of banana?
(b)What are the main challenges she will have
to overcome?
37.List three features of bacterial plasmids that
make them useful tools in genetic engineering.
38.Did the work of Briggs and King in cloning
frogs support or challenge the theory that
cloning could not be successful once the donor
cells had differentiated? Explain.
39.Draw a replication machine and label it. Then
draw a second diagram showing how a chemical
mutagen can disrupt the replication process.
40.Describe the process that is used to create a
viral vector for gene therapy. What are some of
the benefits of using viruses as vectors? What
are some of the risks?INQUIRY41.You are studying DNA replication in bacterial
cells. In one culture, you note that replication
is not producing viable daughter cells. Your
analysis shows that about 50 percent of the
daughter DNA appears normal, while about
50 percent is very unstable and does not form
a double helix.
(a)Draw and label a diagram that could
account for your observations.
(b)If you centrifuged the DNA from this
culture, what would you expect to see?
42.When a suspension of heat-killed pathogenic
bacteria is treated with enzyme X and then
cultured with a strain of non-pathogenic
bacteria, transformation does not occur.
(a)How could you determine whether or not
enzyme X is a restriction endonuclease?
(b)If enzyme X is a restriction endonuclease,
what steps could you take to determine its
restriction site?
43.A lab studying protein synthesis discovers that
three samples of mRNA have been contaminated
by the addition of the nucleotide triplet UAA.