Microbiology Exam 2 Flashcards
Table 8.2
Codon on mRNA and corresponding amino acid
UUA leucine UAA nonsense
GCA alanine AAU sparagine
AAG lysine UGC cysteine
GUU valine UCG, UCU serine
(Use Table 8.2.) What is the sequence of amino acids coded for by the following sequence of bases in a strand of DNA?
3’ ATTACGCTTTGC
A. Asparagine-cysteine-valine-serine
B. Leucine-arginine-lysine-alanine
C. Transcription would stop at the first codon
D. Asparagine-arginine-lysine-alanine
E. Can’t tell
C. Transcription would stop at the first codon
Which enzymes catalyze the elongation of a DNA strand in the direction?
primase DNA ligase helicase topoisomerase DNA polymerases
DNA polymerases
All of the following are functions of DNA polymerase in DNA replication except
proofreading each added nucleotide for correct base
pairing.
covalently adding nucleotides to the new strands.
initiating a polynucleotide strand.
replacing RNA primers with DNA.
initiating a polynucleotide strand.
Which of the following is not transcribed from DNA ?
exons. mRNA. tRNA. rRNA. all are transcribed from DNA
all are transcribed from DNA
Where do transcription and translation occur in prokaryotic cells?
in the cytoplasm in chromatophores in the nucleus in the cell wall on the plasma membrane
in the cytoplasm
A gene is best defined as
A segment of DNA.
A transcribed unit of DNA.
A sequence of nucleotides in DNA that codes for a
functional product.
A sequence of nucleotides in RNA that codes for a
functional product.
Three nucleotides that code for an amino acid.
A sequence of nucleotides in DNA that codes for a functional product.
In an analysis of the nucleotide composition of DNA, which of the following is true?
A = G and C = T A + C = G + T A = C A + T = G + C Both B and C are true.
A + C = G + T
The following questions refer to Figure 17.1, a table of codons.
What amino acid sequence will be generated, based on the following mRNA codon sequence?
5’AUG-UCU-UCG-UUA-UCC-UUG
met-ser-leu-ser-leu-ser
met-glu-arg-arg-gln-leu
met-leu-phe-arg-glu-glu
met-ser-ser-leu-ser-leu
met-ser-ser-leu-ser-leu
Where is the attachment site for RNA polymerase?
operator region promoter region initiation region structural gene region regulator region
promoter region
If you knew the sequence of nucleotides within a gene, which one of the following could you determine with the most accuracy?
The tertiary structure of the protein
The quaternary structure of the protein
The secondary structure of the protein
The primary structure of the protein
Can’t tell
The primary structure of the protein
CTable 8.2
Codon on mRNA and corresponding amino acid
UUA leucine UAA nonsense
GCA alanine AAU sparagine
AAG lysine UGC cysteine
GUU valine UCG, UCU serine
(Use Table 8.2.) If the sequence of amino acids coded for by a strand of DNA is serine-alanine-lysine-leucine, the coding for the template strand of DNA is
5' ACAGTTTCAAT 3' AGACGTTTCAAT 3' TCACGUUUCAAU 3' UGUGCAAAGUUA 3' UCUCGAAAGUUA
3’ AGACGTTTCAAT
Which of the following represents a similarity between RNA and DNA?
the presence of a double-stranded helix
the presence of an OH group on the 3’ carbon of the
sugar
the presence of uracil
repair systems that correct genetic code errors
nucleotides consisting of a phosphate, sugar, and
nitrogen base
nucleotides consisting of a phosphate, sugar, and nitrogen base
A plasmid may
be integrated into the chromosome.
replicate independent of the chromosome.
be transferred cell-to-cell during conjugation.
be involved in any of the above.
be involved in any of the above.
DNA is constructed of
Two strands of identical nucleotides with hydrogen
bonds between them.
Nucleotides bonded AC and GT.
A single strand of nucleotides with internal hydrogen
bonding.
Two strands of nucleotides running antiparallel.
None of the above.
Two strands of nucleotides running antiparallel.
Which of the following is not a product of transcription?
mRNA tRNA rRNA A new strand of DNA None of the above
A new strand of DNA
A cell that cannot make tRNA
Can make proteins if mRNA is provided in the growth
medium.
Can’t make proteins.
Can’t make proteins unless aminoacyl synthetase is
provided in the growth medium.
Can make proteins if amino acids are provided in the
growth medium.
None of the above.
Can’t make proteins.
Which one of the following is false?
The codons in a gene specify the amino acid sequence
of a polypeptide.
Ribosomes function as factories that coordinate the
functioning of mRNA and tRNA.
Transcription occurs in the cytoplasm of eukaryotic cells.
Eukaryotic mRNA is processed in several ways before
export out of the nucleus.
Polypeptides form proteins that determine the
appearance and function of the cell and organism.
Transcription occurs in the cytoplasm of eukaryotic cells.
Which one of the following statements about ribosomes is false?
A ribosome consists of two subunits.
Each ribosome has two binding sites for tRNA.
Subunits of RNA are made of proteins and ribosomal
RNA.
The ribosomes of prokaryotes and eukaryotes are the
same in structure and function.
Ribosomes coordinate the functioning of mRNA and
tRNA.
The ribosomes of prokaryotes and eukaryotes are the same in structure and function.
If you knew the sequence of nucleotides within a gene, which one of the following could you determine with the most accuracy?
The tertiary structure of the protein
The quaternary structure of the protein
The secondary structure of the protein
The primary structure of the protein
Can’t tell
The primary structure of the protein
Genetic change in bacteria can be brought about by
Transduction. Conjugation. Mutation. Transformation. All of the above.
All of the above.
The necessary ingredients for DNA synthesis can be mixed together in a test tube. The DNA polymerase is from Thermus aquaticus and the template is from a human cell. The DNA synthesized would be most similar to
Human DNA. T. aquaticus RNA. A mixture of human and T. aquaticus DNA. Human RNA. T. aquaticus DNA.
Human DNA.
Which of these mechanisms ensures that DNA replication is accurate?
complementary base pairing mismatch repair proofreading excision repair all of the above
all of the above
Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. What percent of the nucleotides in this sample will be thymine?
24 31 12 38 It cannot be determined from the information provided.
12
Which of the following pairs is mismatched?
RNA polymerase makes a molecule of RNA from an RNA
template
DNA gyrase coils and twists DNA
DNA ligase joins segments of DNA
Transposase insertion of DNA segments into DNA
DNA polymerase makes a molecule of DNA from a DNA
template
RNA polymerase makes a molecule of RNA from an RNA template
All of the following are found in prokaryotic messenger RNA except
cytosine. the AUG codon. the UGA codon. uracil. introns.
introns.
Which of the following represents a similarity between RNA and DNA?
the presence of a double-stranded helix
the presence of an OH group on the 3’ carbon of the
sugar
the presence of uracil
repair systems that correct genetic code errors
nucleotides consisting of a phosphate, sugar, and
nitrogen base
nucleotides consisting of a phosphate, sugar, and nitrogen base
Where do transcription and translation occur in prokaryotic cells?
in the cytoplasm in chromatophores in the nucleus in the cell wall on the plasma membrane
in the cytoplasm
Transformation is the transfer of DNA from a donor to a recipient cell
By a bacteriophage. By sexual reproduction. By crossing over. By cell-to-cell contact. As naked DNA in solution.
As naked DNA in solution.
Which enzymes catalyze the elongation of a DNA strand in the 5’ –> 3’ direction?
primase DNA ligase helicase topoisomerase DNA polymerases
DNA polymerases
Which of the following statements is false?
Multiple replication forks are possible on a bacterial
chromosome.
The lagging strand of DNA is started by an RNA primer.
DNA polymerase joins nucleotides in one direction only.
DNA replication proceeds in one direction around the
bacterial chromosome.
The leading strand of DNA is made continuously.
DNA replication proceeds in one direction around the bacterial chromosome.
When does translation begin in prokaryote cells?
during transcription
as soon as the DNA introns are removed from the
template
after the 5’ caps are converted to mRNA
once the pre-mRNA has been converted to mRNA
after a transcription initiation complex has been formed
during transcription
The strands that make up DNA are antiparallel. This means that
base pairings create unequal spacing between the two
DNA strands.
one strand is positively charged while the other is
negatively charged.
the 5’ to 3’ direction of one strand runs counter to the 5’
to 3’ direction of the other strand.
the chromosomes are circular in shape.
the twisting nature of DNA creates nonparallel strands.
the 5’ to 3’ direction of one strand runs counter to the 5’ to 3’ direction of the other strand.
A restriction fragment is
A segment of DNA.
A segment of RNA.
A gene.
Part of a restriction enzyme.
A segment of DNA.
You have a small gene that you wish replicated by PCR. You add radioactively labeled nucleotides to the PCR machine. After 3 replication cycles, how many double-stranded DNA molecules do you have?
4 16 2 Thousands 8
8.
The reaction catalyzed by DNA polymerase.
DNA → DNA mRNA → cDNA DNA → mRNA mRNA → protein Both A and B
DNA → DNA
The following steps are used to make DNA fingerprints. What is the third step?
Collect DNA. Perform electrophoresis. Add stain. Digest with a restriction enzyme. Lyse cells.
Digest with a restriction enzyme.
Which of the following is not a disadvantage of E. coli for making a human gene product?
It lacks endoplasmic reticulum.
It can’t process introns.
It can’t deal with large complex proteins.
their growth rate is faster than eukaryotic host cells
None of the above.
their growth rate is faster than eukaryotic host cells
An enzyme that helps genes move between a chromosome and a plasmid.
DNA ligase DNA polymerase Transposase Restriction enzyme RNA polymerase
Transposase
Restriction enzymes are derived from
Animal cells.
Bacteria.
Viruses.
all of the above.
Bacteria.
DNA fingerprinting does not involve
Restriction enzymes Radiolabeled probes gel electrophoreis Isolation of mRNA RFLPs
Isolation of mRNA
Drug resistance occurs
Against antibiotics and not against synthetic
chemotherapeutic agents.
Because bacteria are normal microbiota.
When antibiotics are taken after the symptoms disappear.
When antibiotics are used indiscriminately.
All of the above.
When antibiotics are used indiscriminately.
The β-lactam antibiotics
prevent chromosomal replication.
inhibit protein synthesis.
inhibit cell wall synthesis.
inhibit plasma membrane synthesis.
inhibit cell wall synthesis.
Most of the available antimicrobial agents are effective against
Protozoa. Viruses. Bacteria. Fungi. All of the above.
Bacteria.
Table 20.2
The following results were obtained from a disk-diffusion test for microbial
susceptibility to antibiotics. Staphylococcus aureus was the test organism.
Antibiotic Zone of Inhibition A 3 mm B 7 mm C 0 mm D 10 mm
In Table 20.2, the antibiotic that exhibited bactericidal action was
A. B. C. D. Can't tell.
Can’t tell.
Agents that kill or destroy bacteria are said to be
bacteriostatic.
bacteriocidal.
inhibitory.
all of the above.
bacteriocidal.
Use of antibiotics in animal feed leads to antibiotic-resistant bacteria because
The antibiotics cause new mutations to occur in the
surviving bacteria, which results in resistance to
antibiotics.
The antibiotics kill susceptible bacteria, but the few that
are naturally resistant live and reproduce, and their
progeny repopulate the host animal.
The few surviving bacteria that are affected by the
antibiotics develop immunity to the antibiotics, which they
pass on to their progeny.
Bacteria from other animals replace those killed by the
antibiotics.
The antibiotics persist in soil and water.
The antibiotics kill susceptible bacteria, but the few that are naturally resistant live and reproduce, and their progeny repopulate the host animal.
The most successful agents used for antiviral chemotherapy are
nucleotide or nucleoside analogs.
semisynthetic antibiotics
protein synthesis inhibitors.
capsid inhibitors.
nucleotide or nucleoside analogs.
Table 20.2
The following results were obtained from a disk-diffusion test for microbial
susceptibility to antibiotics. Staphylococcus aureus was the test organism.
Antibiotic Zone of Inhibition A 3 mm B 7 mm C 0 mm D 10 mm
In Table 20.2, the most effective antibiotic tested was
A. B. C. D. Can't tell.
D.
Which of the following is not involved in making cDNA?
Reverse transcription.
RNA processing to remove introns.
Translation.
Transcription.
Translation.
In many bacteria, genes that confer resistance to antibiotics are carried on
R plasmids. bacterial viruses transposons. exons. Both A and C
Both A and C
Which enzyme would cut this strand of DNA: GCATGGATCCCAATGC?
Enzyme Recognition
EcoRI G↓AATTC
CTTAA↑G
Enzyme Recognition
PstI CTGC↓G
G↑ACGTC
Enzyme Recognition
HindIII A↓AGCTT
TTCGA↑A
Enzyme Recognition
Hae III GG↓CC
CC↑GG
Enzyme Recognition
BamHI G↓GATCC
CCCTAG↑G
Enzyme Recognition
BamHI G↓GATCC
CCCTAG↑G
Antimicrobial peptides work by
Inhibiting protein synthesis. Inhibiting cell-wall synthesis. Disrupting the plasma membrane. Complementary base-pairing with DNA. Hydrolyzing peptidoglycan.
Disrupting the plasma membrane.
The first antibiotic discovered was
Streptomycin. Penicillin. Salvarsan. Sulfa drugs. Quinine.
Penicillin.
Table 20.2
The following results were obtained from a disk-diffusion test for microbial
susceptibility to antibiotics. Staphylococcus aureus was the test organism.
Antibiotic Zone of Inhibition A 3 mm B 7 mm C 0 mm D 10 mm
In Table 20.2, which antibiotic would be most useful for treating a Salmonella infection? A B C D Can't tell
Can’t tell
The antibiotic actinomycin D binds between adjacent G-C pairs, thus interfering with
Transcription. Peptide bond formation. Cellular respiration. Plasma membrane function. Translation.
Transcription.
Protozoan and helminthic diseases are difficult to treat because
They replicate inside human cells.
They don’t have ribosomes.
They don’t reproduce.
Their cells are structurally and functionally similar to
human cells.
None of the above.
Their cells are structurally and functionally similar to human cells.
Semisynthetic antibiotics
have an artificially constructed core that stimulates the
production of “natural products.”
are found in nature but their rate of production is
enhanced in the laboratory.
are natural antibiotics that have been purified by artificial
means.
are natural antibiotics that have been chemically modified
in the laboratory.
are natural antibiotics that have been chemically modified in the laboratory.
Eukaryotic cells are often used as hosts for cloned genes because
they have introns and know what to do with them.
they are able to add sugars on to the expressed protein.
they are the easiest type of host cell to work with.
they are more economical than using bacterial host cells.
they are able to add sugars on to the expressed protein.
An enzyme that cuts double-stranded DNA at specific nucleotide sequences.
RNA polymerase Transposase Restriction enzyme DNA ligase DNA polymerase
Restriction enzyme
All of the following statements about drug resistance are true except
It may be carried on a plasmid.
It may be transferred from one bacterium to another during conjugation.
It may be due to increased uptake of a drug.
It may be due to enzymes that degrade some antibiotics.
It is found only in gram-negative bacteria.
It is found only in gram-negative bacteria.
