1. When Fred Griffith injected mice with a mixture of dead, pathogenic, encapsulated S cells and living unencapsulated R cells of Streptococcus pneumoniae, he discovered that
A. the previously harmless strain (S) had inherited the ability to kill mice.
B. the dead mice teemed with living pathogenic (R) cells.
C. the killer strain (R) was encased in a protective capsule.
D. b and c above
E. all of the above
2. The significance of the experiments in which 32P and 35S were used is that
A. the semiconservative nature of DNA replication was finally demonstrated.
B. it demonstrated that harmless bacterial cells had become permanently transformed through a change in the bacterial hereditary system.
C. it established that pure DNA extracted from disease-causing bacteria transformed harmless strains into killer strains.
D. it demonstrated that radioactively labeled bacteriophages transfer their DNA but not their protein coats to their host bacteria.
E. none of the above
3. Which scientist(s) discovered the basis for the base-pair rule, which states that the amounts of adenine and thymine match, as do the amounts of cytosine and guanine?
A. Avery
B. Griffith
C. Chargaff
D. Hershey and Chase
E. Pauling
4. In the bonding of nitrogenous bases,
A. adenine is paired with cytosine.
B. adenine is paired with guanine.
C. cytosine is paired with thymine.
D. guanine is paired with cytosine.
5. In the bonding of two nucleotides,
A. hydrogen bonds are used.
B. adenine and thymine bind together.
C. purines bind with pyrimidines.
D. double-ring nitrogenous bases connect to single-ring bases.
E. all of the above
6. Replication of DNA
A. produces RNA molecules.
B. produces only new DNA.
C. produces two molecules, each of which is half-new and half-old DNA joined lengthwise to each other.
D. generates excessive DNA, which eventually causes the nucleus to divide.
E. is too complex to characterize.
7. The primary function of DNA ligase is to
A. cut the two strands of the DNA molecule prior to replication.
B. attach free nucleotides to the growing chain.
C. remove bases that might have been inserted incorrectly.
D. seal new short stretches of nucleotides into one continuous strand..
E. fragment old DNA that is no longer of use to the cell.
8. Histone-DNA units are called
A. polysomes.
B. ribosomes.
C. nucleosomes.
D. chromocenters.
E. vesicles.
9. Movement of molecules in an electrophoretic experiment is based on
A. the amount of carbon.
B. the size and charge of the molecules.
C. the number of organic rings.
D. their ease in going into solution.
E. the pH of the test material.
10. A linear stretch of DNA that specifies the sequence of amino acids in a polypeptide is called a(n)
A. codon.
B. intron.
C. messenger.
D. gene.
E. enzyme.
11. __________ molecules carry protein-assembly instructions from the nucleus to the cytoplasm.
A. Template DNA
B. Messenger RNA
C. Transfer RNA
D. Ribosomal RNA
E. all of the above
12. The nitrogenous base found in RNA but not in DNA is
A. adenine.
B. cytosine.
C. guanine.
D. uracil.
E. thymine.
13. The synthesis of an RNA molecule from a DNA template strand is
A. replication.
B. translation.
C. transcription.
D. DNA synthesis.
E. metabolism.
14. The portion of the DNA molecule that is not translated and is a noncoding portion of DNA is composed of
A. introns.
B. anticodons.
C. exons.
D. transcriptons.
E. both c and d, but not a or b
15. The genetic code is made up of units consisting of how many nucleotides?
A. 2
B. 3
C. 5
D. 6
E. 12
16. Each "word" in the mRNA language consists of how many letters?
A. 3
B. 4
C. 5
D. more than 5
E. none of the above
17. Which of the following carries amino acids to ribosomes, where amino acids are linked into the primary structure of a polypeptide?
A. mRNA
B. tRNA
C. hnRNA
D. rRNA
E. all of the above
18. The wobble effect pertains to the matching of
A. codons with anticodons.
B. codons with exons.
C. exons with introns.
D. template DNA with messenger RNA.
E. messenger RNA with ribosomal RNA.
19. A polysome is
A. one of the units of a ribosome.
B. the nuclear organelle that synthesizes RNA.
C. an organelle that functions similarly to a ribosome during meiosis.
D. the two units of a ribosome considered together.
E. an mRNA molecule with several ribosomes attached.
20. Genes located in different regions of the body during embryonic development may
A. be turned on and off.
B. never be turned on.
C. be turned on and left on.
D. be activated for only a short time in one cell and a long time in another cell.
E. all of the above
21. The lactose operon includes
A. an operator.
B. three structural genes that manufacture lactose-metabolizing enzymes.
C. a promoter.
D. a repressor.
E. all but choice d
22. The obvious advantage of the lactose operon system is that
A. lactose is not needed as an energy source for bacteria.
B. lactose-metabolizing enzymes need not be made when lactose is not present.
C. the bacteria will make lactose only in the presence of the proper enzymes.
D. milk is no longer needed in the diet of adult humans.
E. glucose can substitute for lactose in the diet of intolerant persons.
23. The positive control of the lactose operon in bacteria is
A. activated by a repressor protein.
B. independent of glucose concentrations.
C. activated by a protein known as CAP.
D. regulated by RNA polymerase.
E. all of these
24. The model of the prokaryote operon explains the regulation of which of the following?
A. replication
B. transcription
C. induction
D. Lyonization
E. none of the above
25. A repressor protein binds with
A. messenger RNA.
B. the operator.
C. the regulator.
D. a product.
E. a substrate.
26. Eukaryotic nucleosomes exert control at what level?
A. transcriptional
B. transcript processing
C. transport
D. translational
E. post-transcriptional
27. This item contains regulator, promoter, and operator regions.
A28. A repressor protein can shut down transcription by binding to this item.
B29. When the repressor is inactivated, RNA polymerase can bind to this item and allow transcription to occur.
C30. Small circular molecules of "extra" DNA in bacteria are called
A. plasmids.
B. desmids.
C. pili.
D. F particles.
E. transferins.
31. Enzymes used to cut genes in recombinant DNA research are
A. ligases.
B. restriction enzymes.
C. transcriptases.
D. DNA polymerases.
E. replicases.
32. The "natural" use of restriction enzymes by bacteria is to
A. integrate viral DNA.
B. destroy viral DNA.
C. repair "sticky ends."
D. copy the bacterial genes.
E. clone DNA.
33. Which of the following enzymes joins the paired sticky ends of DNA fragments?
A. reverse transcriptase
B. restriction enzymes
C. DNA ligase
D. DNA polymerase
E. transferase
34. Separation of DNA fragments by gel electrophoresis
A. requires priming.
B. is controlled by the size of the fragment.
C. is based upon the negative charges of phosphate groups.
D. is easily accomplished.
E. all are correct except a
35. The use of RFLPs for "genetic fingerprinting" is based upon
A. the type of gel used in electrophoresis.
B. identical alleles at loci.
C. differences of locations where enzymes make their cuts.
D. differences between blood and semen DNA.
E. bonding of DNA to RNA.
36. RNA can manufacture DNA via the action of
A. DNA polymerase.
B. RNA polymerase.
C. reverse transcriptase.
D. ligase.
E. restriction endonuclease.
37. Because it has no introns, researchers prefer to use __________ when working with human genes.
A. cDNA
B. cloned DNA
C. hybridized DNA
D. RFLPs
E. viral DNA
38. Collections of DNA fragments produced by restriction enzymes and incorporated into cloning vectors is this.
D39. A collection of DNA fragments produced by restriction enzymes and incorporated into plasmids is called
A. copied DNA.
B. transcribed DNA.
C. DNA amplification.
D. a DNA library.
E. plasmid DNA.
40. Recombinant DNA technology
A. uses bacteria to make copies of the desired product.
B. splices DNAs together.
C. is possible only between closely related species.
D. a and b only
E. a, b, and c
41. New genetic combinations result from
A. crossing over.
B. sexual reproduction.
C. mutations.
D. exchange of genes between different species.
E. all of the above
42. Molecules that interact with DNA to alter gene expression are
A. operons.
B. promoters.
C. regulatory proteins.
D. repressor amines.
E. carbohydrates.
43. When a gene transcription occurs, which of the following is produced?
A. more DNA
B. protein or polypeptide sequences
C. messenger RNA
D. enzymes
E. genetic defects
44. Which of the following is the region that is the binding site for RNA polymerase?
A. heterogeneous nuclear DNA
B. repressor gene
C. promoter sequence
D. operator sequence
E. all of the above
45. The RNA molecule is made up of how many strands?
A. 1
B. 2
C. 3
D. 6
E. 12
46. Before leaving the nucleus, the RNA molecule
A. acquires a poly-A tail.
B. breaks loose from the terminator signal on the template.
C. becomes capped.
D. is stripped of its introns.
E. all of the above
47. Which of the following could NOT be an RNA transcript?
A. AUGCGU
B. ATGCGT
C. UACGCA
D. UAGCGU
E. GCGUUU
48. The building blocks of nucleic acids are
A. amino acids.
B. nucleotides.
C. pentose sugars.
D. phosphate groups.
E. nitrogenous bases.
49. Which of the following statements is true?
A. The hydrogen bonding of cytosine to guanine is an example of complementary base pairing.
B. Adenine always pairs up with guanine in DNA, and cytosine always teams up with thymine.
C. Each of the four nucleotides in a DNA molecule has the same nitrogen-containing base.
D. When adenine base pairs with thymine, they are linked by three hydrogen bonds.
E. In the DNA of all species, the amount of purines never equals the amount of pyrimidines.
50. The appropriate adjective to describe DNA replication is
A. nondisruptive.
B. semiconservative.
C. progressive.
D. natural.
E. lytic.