Deck 7: Microbial Genetics

Question 1

Which of the following statements is true of bacterial plasmids?

A) They are always found in the nucleoid.
B) They can replicate autonomously.
C) They carry genes for essential metabolic functions.
D) They are small circular DNA molecules.
E) They are small circular DNA molecules that can replicate autonomously.

Answer 1

E

Question 2

Which of the following types of plasmids allows a bacterial cell to kill its competitors?

A) virulence plasmids
B) fertility plasmids
C) bacteriocin plasmids
D) resistance plasmids
E) cryptic plasmids

Answer 2

C

Question 3

Which of the following is found in both archaeal and eukaryotic genomes?

A) chromatin fibers
B) histones
C) heterochromatin
D) euchromatin
E) nuclear envelope

Answer 3

B

Question 4

A bacterial genome is typically

A) a single linear piece of DNA.
B) multiple linear pieces of DNA.
C) a linear RNA molecule.
D) a single circular DNA molecule.
E) multiple circular DNA molecules.

Question 5

Amino acids are delivered in their appropriate order by

A) mRNAs.
B) RNA-induced silencing complexes (RISC).
C) ribozymes.
D) rRNAs.
E) tRNAs.

Question 6

Which of the following is NOT a characteristic of Okazaki fragments?

A) They are checked for accuracy by DNA polymerase III.
B) They make up the lagging strand of replicated DNA.
C) They begin with an RNA primer.
D) They are joined together by DNA ligase.
E) They are longer in eukaryotic cells.

Question 7

Semiconservative DNA replication means that

A) each daughter DNA molecule is composed of one original strand and one new strand.
B) nucleotides are constantly being recycled as cells make DNA.
C) the cell can proofread its newly synthesized DNA only part of the time.
D) the sequence of a DNA molecule is preserved as it is being replicated.
E) each strand of a double-stranded DNA molecule is replicated differently.

Question 8

Which of the following is found at the 5' end of a DNA strand?

A) a phosphate group
B) a hydrogen bond
C) a hydroxyl group
D) histones
E) a methyl group

Question 9

Which of the following is NOT a characteristic of both DNA and RNA polymerases?

A) directionality of synthesis
B) energy is provided by pyrophosphate
C) hydrogen bonding of complementary nucleotides
D) requirement for an initiation signal
E) requirement for a primer

Question 10

During elongation, a charged tRNA first enters the ribosomal ________ site and then moves into the ________ site.

A) A; E
B) P; A
C) P; E
D) A; P
E) E; A

Question 11

Which of the following is both a codon for an amino acid and a start signal?

A) AAA
B) AUG
C) UAG
D) GAU
E) UGA

Question 12

Two bacterial strains have the same genes for metabolizing a carbohydrate, but one is wild-type for a regulatory inducer while the other does not produce the inducer. Which of the following statements is CORRECT with regard to the metabolism of the bacteria?

A) The two bacterial strains have the same phenotype.
B) The two bacterial strains have different phenotypes.
C) The genotypes and phenotypes of the two bacterial strains are the same.
D) The two bacterial strains have the same phenotype but have different genotypes.
E) The answer cannot be determined from the information provided.

Question 13

Which of the following is a characteristic shared by DNA and RNA polymerases?

A) efficiency of proofreading
B) type of nucleotides used
C) direction of polymerization
D) speed
E) dependence on helicase

Question 14

DNA is composed of four nucleotides, A, C, G and T. Each codon is composed of three nucleotides. The number of possible codons is

A) 16.
B) 4.
C) 12.
D) 64.
E) 32.

Question 15

The bacterial chromosome is

A) usually found in the cytoplasm.
B) found in a nucleoid.
C) found in a nucleus.
D) both circular and found in a nucleoid.
E) both circular and found in a nucleus.

Question 16

Typical eukaryotic genomes are composed of ________ chromosomes.

A) multiple linear
B) multiple circular
C) a single circular
D) a single linear
E) both linear and circular

Question 17

Which of the following is involved in translation?

A) rRNA only
B) tRNA only
C) mRNA only
D) both mRNA and tRNA
E) mRNA, rRNA, and tRNA are all involved.

Question 18

The process indicated by the arrow in Figure 7.1 represents

A) lagging strand synthesis.
B) leading strand synthesis.
C) transcription.
D) translation.
E) recombination.

Question 19

Which of the following processes is involved in the "central dogma" of genetics?

A) translation only
B) transcription only
C) DNA replication only
D) transcription and translation
E) DNA replication and translation

Question 20

Which of the following statements concerning transcription in bacteria is FALSE?

A) It occurs in the nucleoid region.
B) Sigma factors are parts of RNA polymerase that recognize promoter regions.
C) Different RNA polymerases are required for synthesis of mRNA, rRNA, and tRNA.
D) Termination is either self-induced or due to the presence of Rho protein.
E) There are a variety of sigma factors that affect transcription.

Question 21

Prokaryotic operons typically include a(n) ________ and a(n) ________ with multiple genes.

A) operator; terminator
B) operator; promoter
C) promoter; repressor
D) inducer; repressor
E) CAP-binding site; inducer

Question 22

DNA damage caused by nitrous acid results in ________ mutations.

A) insertion
B) substitution
C) deletion
D) frameshift
E) both insertion and deletion

Question 23

The process of ________ requires the activity of DNA ligase.

A) translation
B) capping
C) transcription
D) DNA replication
E) transduction

Question 24

Frederick Griffith discovered

A) transformation.
B) transposons.
C) the lac operon.
D) DNA.
E) conjugation.

Question 25

Which of the following are considered to be frameshift mutations?

A) insertions only
B) inversions only
C) deletions only
D) both inversion and insertions
E) both deletions and insertions

Question 26

You observe a microbiologist examining two plates and notice the pattern of colonies are nearly identical with the exception of a few colonies that are absent on one of them. The plates likely were produced by

A) positive selection culturing.
B) replica plating.
C) pour plating.
D) streak plating.
E) the Ames test.

Question 27

In conjugation, F⁺ cells

A) serve as recipient cells.
B) contain an F plasmid.
C) do not have conjugation pili.
D) can transfer DNA only to other F⁺ cells.
E) contain "jumping genes."

Question 28

Which of the following is required for transposition?

A) F+ plasmid
B) bacteriophage
C) insertion sequence
D) donor cell
E) competence

Question 29

The horizontal transfer process known as transduction

A) involves a virus.
B) requires a pilus.
C) requires a cell to be "competent."
D) requires a plasmid.
E) involves a mutagen.

Question 30

Which of the following DNA repair processes is most likely to introduce mutations into the repaired DNA?

A) base-excision repair
B) light repair
C) single-strand repair
D) mismatch repair
E) SOS response repair

Question 31

The events of ________ are initiated at sequences called origins.

A) DNA replication
B) translation
C) splicing
D) transcription
E) transposition

Question 32

The Ames test demonstrates that a chemical is

A) carcinogenic.
B) carcinogenic in Salmonella.
C) mutagenic in Salmonella.
D) carcinogenic in humans.
E) mutagenic in humans.

Question 33

A polypeptide in a wild type microbe contains the sequence Leu-Pro-Tyr-Ser-Pro. A phenotypic variant of the species has the peptide sequence Leu-Pro-Cys-Ser-Pro. This is an example of a(n) ________ mutation.

A) nonsense
B) missense
C) silent
D) frameshift
E) inversion

Question 34

Which of the following causes mutations by creating thymine dimers?

A) nucleotide analogs
B) nitrous acid
C) ultraviolet light
D) benzopyrene
E) gamma rays

Question 35

Which of the following is characteristic of prokaryotic genomes but not eukaryotic genomes?

A) histones
B) circular chromosomes
C) linear chromosomes
D) enclosed in a nuclear membrane
E) typically consist of a few to several chromosomes

Question 36

Codons are recognized during

A) translation.
B) transcription.
C) base excision.
D) DNA replication.
E) transduction.

Question 37

RNA polymerase is primarily responsible for

A) DNA replication.
B) translation.
C) transcription.
D) transformation.
E) polyadenylation.

Question 38

If the codon AAA is changed to AAG, it still codes for the amino acid lysine; this is an example of a

A) silent mutation.
B) nonsense mutation.
C) frameshift mutation.
D) dimer formation.
E) missense mutation.

Question 39

Genetic elements known as promoters are initiation points in the process of

A) DNA replication.
B) transcription.
C) translation.
D) mutation repair.
E) transformation.

Question 40

Which of the following is NOT involved in the regulation of the lac operon?

A) an inducer
B) a repressor protein
C) an iRNA
D) glucose
E) cyclic AMP

Question 41

A(n) (operon/codon/gene) is a specific sequence of nucleotides that codes for a protein or an RNA molecule.

Question 42

A chemical is reported to inhibit bacterial replication. Bacterial cells are placed in medium with all nutrients necessary for replication. The chemical is added to the culture, and after a half hour an extract of the DNA is prepared. A significant percentage of the DNA is in pieces about 1000 to 2000 bases in length. The results are consistent with the chemical blocking the function of DNA ligase.

Question 43

The effects of a transposition event are equivalent to a(n)

A) nonsense mutation.
B) missense mutation.
C) frameshift mutation.
D) silent mutation.
E) HFR conjugation.

Question 44

The structure of DNA explains both its ability to encode genetic information and the way in which it is copied during cell reproduction.

Question 45

DNA, which is negatively charged, wraps around positively charged histones as part of the packaging of eukaryotic chromosomes.

Question 46

Loosely packed, transcriptionally active regions of a eukaryotic chromosome are called (euchromatin/heterochromatin/nucleosomes).

Question 47

The process of ________ is described as semiconservative.

A) translation
B) transcription
C) mismatch repair
D) transformation
E) DNA replication

Question 48

Nucleotide analogs cause frameshift mutations.

Question 49

Most bacteria have a natural ability to take up DNA from their environment.

Question 50

All eukaryotes are diploid.

Question 51

The modified amino acid fMet is essential for

A) bacterial translation.
B) bacterial transcription.
C) eukaryotic transcription.
D) eukaryotic translation.
E) eukaryotic mRNA processing.

Question 52

Which of the following processes occurs in eukaryotes but not prokaryotes?

A) DNA replication
B) capping
C) transcription
D) translation
E) gene regulation

Question 53

The phenotype of an organism is its set of (genes/traits/chromosomes).

Question 54

In generalized transduction, viruses carry random DNA sequences from one cell to another.

Question 55

Transfer of DNA between bacterial cells by viruses is called (transformation/transduction/conjugation).

Question 56

The phenotype of an organism reflects only part of its genotype.

Question 57

In contrast to leading strand synthesis, the lagging strand is synthesized 3' to 5', which is why it is slower.

Question 58

The enzyme responsible for separating the DNA strands during DNA replication is (topoisomerase/primase/helicase).

Question 59

The term "semiconservative replication" means that both strands of a DNA molecule are a mix of newly replicated and original template DNA.

Question 60

Transfer of random pieces of DNA mediated by phage is known as

A) transformation of competent cells.
B) generalized transduction.
C) conjugation.
D) transposition.
E) specialized transduction.

Question 61

A point mutation can be completely harmless, or it can result in the death of a cell or organism. Explain why these types of mutations can have such varying effects.

Question 62

The chemical 5-bromouracil mimics the chemical structure of thymine, making it a(n) (analog/nucleotide/precursor) of thymine.

Question 63

Nucleotide analog mutagens cause (deletion/frameshift/point) mutations.

Question 64

Describe the various types of nucleic acids that are typically found in cells.

Question 65

Compare and contrast the lactose operon with the tryptophan operon.

Question 66

The (leading/lagging/replicating) strand is the DNA strand that is synthesized continuously during DNA replication.

Question 67

Describe the basic similarities and differences between DNA replication and transcription.

Question 68

A(n) (genome/codon/operon) is a set of prokaryotic genes that are regulated and transcribed as a unit.

Question 69

Bacterial strain A contains a plasmid. Bacterial strain B does not. When the bacteria are incubated together in a broth culture strain B cells containing the plasmid can be isolated. Devise an experiment to determine what type of gene transfer process is involved.

Question 70

The full set of genetic instructions of an organism is its (phenotype/genome/genotype).

Question 71

Except during initiation of translation, transfer RNA molecules carrying amino acids initially bind to the ribosome at the (P/A/E) site.

Question 72

The (codon/anticodon/loop) of a transfer RNA molecule is complementary to a codon in a messenger RNA molecule.

Question 73

Errors made during replication are primarily corrected by (base-excision/mismatch/nucleotide-excision) repair.

Question 74

A (missense/nonsense/silent) mutation of a gene usually produces a nonfunctional polypeptide.

Question 75

While studying a bacterial strain, a scientist notes a short DNA sequence between inverted repeats is present in both the chromosome and a plasmid within the cell. This sequence is most likely a(n) (phage/transposon/F plasmid).