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CHAPTER 18-20 EXAM
1. The function of reverse transcriptase in retroviruses is to
a. hydrolyze the host cell’s DNA
b. use viral RNA as a template for DNA synthesis
c. convert host cell RNA into viral DNA
d. translate viral RNA into proteins
e. use viral RNA as a template for making complementary RNA strands
2. Viruses have some of the properties of living organisms. Which of the following is a
characteristic of all organisms, but NOT of viruses?
a. genetic information stored as nucleic acid
b. ability to reproduce
c. structure includes protein
d. plasma membrane
3. In a hospital, a bacterium is isolated that is resistant to an antibiotic previously used
against other kinds of bacteria. This is most likely the result of
a. transposition
b. reverse transcriptase
c. transformation
d. insertion
4. Which of the following is a TRUE statement about viruses?
a. Viruses are classified below the cellular level of biological organization.
b. A virus particle contains both DNA and RNA.
c. Individual virus particles are visible with light microscopes.
d. Assembly of viral capsids from proteins requires host cell assistance.
5. Bacteriophages that have become integrated into the host cell chromosome are called
a. intemperate bacteriophages
b. transposons
c. prophages
d. T-even bacteriophages
e. plasmids
6. A mutation in this gene could change the rate at which RNA polymerase binds to the
DNA.
a. operon
b. operator
c. promoter
d. repressor
7. The binding of an active repressor molecule at this site prevents the binding of RNA
polymerase
a. operon
b. operator
c. promoter
d. repressor
Use the following answers for Questions 8-16. The answers may be used once, more than once,
or not at all.
a. transduction
b. transposition
c. transformation
d. conjugation
8. A DNA segment is moved from one location to another.
9. DNA is transferred from one bacterium to another by a virus.
10. DNA from one strain of bacteria is assimilated by another strain.
11. A plasmid is exchanged between bacteria through a pilus.
12. DNA from pneumonia-causing bacteria is mixed with harmless bacteria. The bacteria are
injected into mice. The mice develop pneumonia and die.
13. A group of F+ bacteria is mixed with a group of F- bacteria. After several days, all of the
bacteria are F+.
14. Bacterial strains A and B are growing together in a colony that has been infected with
viruses. After a short period of time, a new strain of bacteria is detected that is very
similar to strain A but has a few characteristics of strain B.
15. Bacteria have proteins on the surface that recognize and take in DNA from closely related
species.
16. “Selfish DNA” is found at several sites in the genome of the bacterium.
17. Which of the following represents a difference between viruses and viroids?
a. Viruses infect many types of cells while viroids infect only prokaryotic cells.
b. Viruses have capsids composed of protein while viroids have no capsids.
c. Viruses contain introns while viroids have only exons.
d. Viruses have genomes composed of DNA while viroids have genomes composed
of RNA.
e. Viruses cannot pass through plasmodesmata while viroids can.
18. In which of the following cases would a mutation have the most significant impact on the
genetic diversity of a species?
a. The species reproduces only asexually.
b. The species reproduces only sexually.
c. The species usually reproduces asexually, but can reproduce sexually when
conditions become unfavorable..
d. The species has a relatively long reproductive cycle.
e. The species’ reproductive cycle is unpredictable.
19. An Hfr bacterium is one that has
a. at least one plasmid present in the cytosol
b. a special recognition site that will take up closely related DNA from its
environment
c. several insertion sequences scattered throughout its chromosome
d. several copies of a single transposon repeated randomly throughout its
chromosome
e. a F plasmid that has become integrated into its chromosome
20. Histones are
a. small, positively charged proteins that bind tightly to DNA
b. small bodies in the nucleus involved in rRNA synthesis
c. basic units of DNA packing consisting of DNA wound around a protein core
d. repeating arrays of six nucleosomes organized around an H1 molecule
e. proteins responsible for producing repeating sequences at telomeres
21. All of the following are potential control mechanisms for regulation of gene expression in
eukaryotic organisms EXCEPT
a. the degradation of mRNA
b. the transport of mRNA from the nucleus
c. the lactose operon
d. transcription
e. gene amplification
22. A eukaryotic gene typically has all of the following features EXCEPT
a. introns
b. a promoter
c. an operator
d. a start base triplet
e. a transcriptional stop message
23. The gene that stimulates tumorgenesis in Burkitt’s lymphoma is expressed when it is
moved to chromosome 14 from chromosome 8. This is an example of gene expression
regulated by
a. diffusible factors
b. gene amplification
c. steroid hormones
d. translocation
e. point mutations
24. The processing of the RNA transcript involves
a. the removal of introns and the splicing together of exons
b. the removal of exons and the splicing together of introns
c. the addition of guanine cap and a poly-A tail
d. the attachment of introns to ribosomal RNA
e. Both a and c are correct.
25. In which of the following would you expect to find the most methylation of the DNA?
a. tandem arrays for ribosomal genes
b. pseudogenes
c. Barr bodies
d. globin genes
e. transposons
26. What percentage of the DNA in a typical eukaryotic cell is expressed at any given time?
a. 3-5%
b. 5-20%
c. 20-40%
d. 40-60%
e. 60-90%
27. In a nucleosome, what is the DNA wrapped around?
a. polymerase molecules
b. ribosomes
c. mRNA
d. histones
e. nucleolus protein
28. In eukaryotes, what is the active transcription generally associated with?
a. euchromatin only
b. heterochromatin only
c. very tightly packed DNA only
d. highly methylated DNA only
e. both euchromatin and highly methylated DNA
29. Chromsome puffs are thought to represent chromosomal regions where
a. genes are inactivated by repressor proteins
b. genes are especially active in transcription
c. hormones are produced
d. regulatory genes are located
e. genes have been damaged
30. Muscle cells and nerve cells in one kind of animal owe their differences in structures to
a. having different genes
b. having different chromosomes
c. using different genetic codes
d. expressing different genes
e. having unique ribosomes
31. What is meant by the word metastasis?
a. the transformation of a normal cell to a cancer cell
b. a mutation that causes cancer
c. the spread of cancer cells from their site of origin
d. the activation of an oncogene
e. the development of contact inhibition
32. A difference between prokaryote and eukaryote RNA is that
a. prokaryote RNA has uracil, eukaryote RNA has thymine
b. eukaryote RNA lasts much longer before being degraded
c. prokaryote RNA never leaves the cell nucleus
d. prokaryote RNA contains deoxyribose
e. eukaryote RNA is in the form of a double helix
33. What do pseudogenes and introns have in common?
a. They code for RNA end products, rather than proteins.
b. They both contain uracil.
c. They have multiple promoter sites.
d. They both code for histones.
e. They are not expressed nor do they code for functional proteins.
34. If the structure of a TV show is analogous to the structure of a gene, then the introns of a
gene would be analogous to
a. the opening theme music
b. the segments of the show
c. the commercials between segments of the show
d. the commercials between shows
e. the closing credits
35. Which of the following DNA sequences would most likely be a restriction site?
a. AACCGG
TTGGCC
b. GGTTGG
CCAACC
c. AAGG
TTCC
d. AATTCCGG
TTAAGGCC
e. CTGCAG
GACGTC
36. Biotechnology is presently being used to do which of the following?
a. produce vaccines
b. correct defects in human germ cells
c. produce human gene products
d. Only a and c are correct.
e. a, b and c are correct
37. It is theoretically possible for a gene from any organism to function in any other
organism. Why is this possible?
a. All organisms have the same genetic code.
b. All organisms are made up of cells.
c. All organisms have similar nuclei.
d. All organisms have transfer RNA.
38. The polymerase chain reaction is important because it allows us to
a. insert eukaryotic genes into prokaryotic plasmids.
b. incorporate genes into viruses.
c. make DNA from RNA transcripts.
d. make many copies of specific segments of DNA.
e. insert regulatory sequences into eukaryotic genes.
Use the following choices to answer Questions 39-42. Each choice may be used once, more than
once, or not at all.
a. restriction endonuclease
b. DNA ligase
c. reverse transcriptase
d. RNA polymerase
e. DNA polymerase
39. Which enzyme permanently seals together DNA fragments that have complementary
sticky ends?
40. Which enzyme is used to make complementary DNA (cDNA)?
41. Which enzyme is used to make multiple copies of genes in the polymerase chain reaction
(PCR)?
42. Which enzyme is used to produce RFLPs?
43. If you discovered a bacterial cell that contained no restriction endonuclease, which of the
following would you expect to happen?
a. The cell would be unable to replicate its DNA.
b. The cell would create incomplete plasmids.
c. The cell would be easily infected and lysed by bacteriophages.
d. The cell would become an obligate parasite.
e. Both a and d would occur.
44. A DNA fingerprint is produced by
a. treating selected segments of DNA with restriction enzymes
b. electrophoresis of restriction fragments
c. oligonucleotides from PCRs
d. electroporation of cDNAs
e. Both a and b are correct.
45. Reverse transcriptase is important in genetic engineering because
a. it is found in retroviruses
b. it allows us to make DNA from RNA
c. it allows bacteria to translate eukaryotic RNA
d. it removes exons from eukaryotic genes
e. both c and d are correct
Questions 46-49 refer to the techniques, tools or substances below. Answers may be used once,
more than once, or not at all.
a. restriction enzymes
b. gene cloning
c. DNA ligase
d. gel electrophoresis
e. reverse transcriptase
46. Produces many copies of a gene for basic research or for large-scale production of a gene
product.
47. Enables one to create complementary DNA (cDNA) from mRNA; results in a smaller
gene product (RNA processed – no introns) that is more easily translated by bacteria
48. Separates molecules by movement due to size and electrical charge
49. Seals the sticky ends of restriction fragments to make recombinant DNA
50. What is the genetic function of restriction endonucleases?
a. adds new nucleotides to the growing strand of DNA
b. joins nucleotides during replication
c. joins nucleotides during transcription
d. cleaves nucleic acids at specific sites
e. repairs breaks in sugar-phosphate backbones
ESSAY
Answer BOTH of the following questions below as completely and as thoroughly as
possible. Answer the question in essay form (NOT outline form), using complete sentences.
You may use diagrams to supplement your answer, but a diagram alone without
appropriate discussion is inadequate.
1. Contrast the methods in which bacteria and virus are transmitted from cell to cell.
(Discuss the reproductive cycles of viruses in the answer).
2. Describe the methods in which gene expression is regulated within a eukaryote. Describe
one method used to regulate gene expression in prokaryotes that is different than what
you have described.