Ch. 8 Microbiology Assignment Questions
recognition and repair of errors in nucleotide incorporation by DNA polymerase is called a) excision repair b) mismatch repair c) photoactivation d) proofreading
d) proofreading
a large segment of a cell's genome that originated in other species is called a(n) - genomic island - genomic library - virulence factor - fertility factor - genomic imprint
genomic island
the consequences of not repairing damaged DNA in cells include - cell death - cancer (in animals) - cells that have less mutations
- cell death - cancer (in animals)
chromosomes - ___ can't survive their loss - found in all ___ and ___
- cells - eukaryoes, prokayotes
___ are an excellent experimental system for genetic studies because they can grow to high densities allowing us to screen for rare genetic events
bacteria
chemicals that modify nucleobases change their ___-___ properties
base pairing
___ are chemicals that cause cancer
carcinogens
a bacterial cell described as ___ can take up DNA from the surrounding environment
competent
donor DNA that is injected into a recipient cell by a phage integrates into the recipient's chromosome by ___ ___
homologous recombination
when 2 bacterial strains that are his-/trp- (require his and trp for growth) and leu-/thr- (require leu and thr for growth) are mixed together and plated on minimal media, any colonies that form are likely due to one strain acquiring genes from another strain. This is called ___ ___ ___
horizontal gene transfer
the ___ gene pool consists of genes that can move from one DNA molecule to another
mobile
can replicate in only one species
narrow host range
___ ___ is the process by which organisms which are better adapted to an environment reproduce at a higher rate than those who are not
natural selection
in bacterial conjugation, F+ donor cells are high frequency recombinant (Hfr) cells when the F ___ is integrated into the chromosome
plasmid
a bacteriophage consists of a(n) ___ coat that surrounds the nucleic acid ___
protein, genome
___ is the change of a mutated genetic sequence back to its original, non-mutated form
reversion
most transposons contain ___ terminators
transcriptional
which mechanism of gene transfer involves the uptake of "naked" DNA by competent bacterial recipient cells - transformation - conjugation - transduction - transposition
transformation
"jumping genes," or ___, can lead to changes in genotype within a cell or between cells
transposons
T/F: bacterial genetics can help explain why there are increasing numbers of bacteria that are resistant to many different antibiotics
true
T/F: the native or wild type strain describes the typical phenotype of strains isolated from nature
true
the type of transduction that can transfer any genes of a host cell is called ___ transduction a) generalized b) specialized c) randomized d) localized
generalized
a ___ plasmid can be transferred to another bacterial cell when it is in the same cell as a conjugative plasmid
mobalizable
can replicate in many different species
broad host range
in insertion sequences, the ___ gene (the only gene) is flanked by ___ repeats
transposase, inverted
bacteriophages can consist of - nucleus - DNA genome - hybrid DNA/RNA genome - protein coat (capsid) - membrane (envelope) - RNA genome
- DNA genome - protein coat (capsid) - RNA genome
it is important for people interested in human health to have a basic understanding of bacterial genetics because it can help explain how: - effective penicillin is against most bacteria - bacteria acquire resistance traits - multi-drug resistant bacteria like MRSA arise
- bacteria acquire resistance traits - multi-drug resistant bacteria like MRSA arise
place the steps of DNA mediated transformation in the correct order - nucleases degrade one strand of double stranded DNA at the cell surface - single stranded DNA integrates into genome after entering the cell - single stranded DNA enters the cell after one strand has been degraded - double stranded DNA molecule binds to surface receptor
- double stranded DNA molecule binds to surface receptor - nucleases degrade one strand of double stranded DNA at the cell surface - single stranded DNA enters the cell after one strand has been degraded - single stranded DNA integrates into genome after entering the cell
in bacterial conjugation, a donor cell with an F ___ located in the cytoplasm is considered F+ a) pilus b) plasmid c) fimbrae d) chromosome e) complex
plasmid
the distortion of DNA by thymine dimers directly blocks which of the following cellular processes - translation - replication - respiration - transcription
- replication - transcription
chemical mutagens can cause which of the following - thymine dimers - frameshift mutations - double stranded breaks - base substitutions
- frameshift mutations - base substitutions
plasmids - typically don't encode genes that are ___ - are often the location of ___ in bacteria
- genes essential to the life of the cell - antibiotic resistance genes in bacteria
these chemicals, produced in aerobic environments, lead to the oxidation of guanine in DNA resulting in increased base substitutions - hydrogen peroxide - adenine - superoxide - reactive oxygen species
- hydrogen peroxide - superoxide
if a scientist is working with a bacterium that has the typical phenotype of strains isolated from nature, that bacterium is called a ___ type
wild
some of the disadvantages of using the SOS DNA polymerase include: - it competes with the standard DNA polymerase - it can result in a lot of mutations in the DNA - it only works on undamaged DNA - it has no proofreading ability
- it can result in a lot of mutations in the DNA - it has no proofreading ability
which of the following are replicons? - chromosome fragment - plasmid - chromosome
- plasmid - chromosome
which of the following are components of the simplist transposon, an insertion sequence - origin of replication - inverted repeats - reverse transcriptase - antibiotic resistance gene - transposase gene
- inverted repeats - transposase gene
x rays can cause which types of damage to a DNA molecule - nucleobase alterations - single stranded breaks - double stranded breaks - thymine dimer formation
- nucleobase alterations - single stranded breaks - double stranded breaks
which of the following can be transferred from one cell to another by conjugation - plasmid DNA - chromosomal DNA - bacterial RNA - bacterial proteins - phage DNA
- plasmid DNA - chromosomal DNA
a ___ mutation occurs if a single base pair is changed during DNA synthesis
point mutation
which of the following types of radiation are mutagenic - infrared rays - x rays - ultraviolet rays
- x rays - ultraviolet rays
which of the following are examples of mobile genetic elements - phage DNA - genomic islands - transposons - plasmids - chromosomal DNA
- phage DNA - genomic islands - transposons - plasmids
chemical mutagens that squeeze between base pairs and induce frameshift mutations are called ___ a) intercalating agents b) alkylating agents c) thymine dimers d) base analogs
a) intercalating agents
genetic change in bacteria occurs through which two mechanisms a) mutation b) horizontal gene transfer c) vertical gene transfer
a) mutation b) horizontal gene transfer
when excision errors produce plasmids containing both chromosomal and F plasmid DNA, the resulting plasmid is called a(n) ___ plasmid
F prime
which enzyme degrades short stretches of DNA that contain modified nucleobases a) DNA polymerase b) DNA helicase c) DNA ligase d) RNA polymerase
a) DNA polymerase
when DNA is transferred from an Hfr cell to a recipient cell, the recipient is a(n) ___ cell a) F- b) F+ c) competent d) Hfr
a) F-
which of the following plasmids encodes all the necessary genetic information for transfer from one bacterial cell to another a) conjugative plasmids only b) mobilizable plasmids only c) both conjugative and mobilizable plasmids
a) conjugative plasmids only
which type of mutation alters the reading frame of a gene a) frameshift b) reversion c) missense
a) frameshift
if a bacterial cell spontaneously mutates to become resistant to an antimicrobial drug, this bacterium will ___ when the antimicrobial drug is present a) grow without competition b) not grow as well as all the other bacteria c) grow as well as all the other bacteria
a) grow without competition
___ sometimes incorporates the incorrect nucleotide when generating a new strand of DNA during DNA ___; this leads to a detectable distortion in the DNA helix a) DNA polymerase; transcription b) DNA polymerase; replication c) RNA polymerase; transcription d) RNA polymerase; replication
b) DNA polymerase; replication
___ repair is activated by extensive DNA damage and uses polymerases that lack proofreading ability, ultimately resulting in mutations a) photoreactivation b) SOS c) excision d) proofreading e) mismatch
b) SOS
which is an agent that induces changes in DNA a) mutation b) mutant c) mutagen
c) mutagen
mutants that can grow under conditions in which the parent (wild type) cells cannot are easily isolated by ___ selection
direct
mutant cells in a bacterial culture can be identified by ___ and ___ selection methods
direct, indirect
___ plasmids encode resistance to a variety of antimicrobial agents and heavy metals a) X b) F c) A d) Ti e) R
e) R
function of R genes
encode resistance traits
function of RTF
encodes properties needed for conjugation
the integration of a region of DNA into a segment that does not have extensive similarity in nucleotide sequence is called a) vertical gene transfer b) homologous recombination c) generalized transduction d) specialized transduction e) horizontal gene transfer f) non homologous recombination
f) non homologous recombination
T/F: a point mutation always leads to a shift of the reading frame from the point of mutation downstream
false
T/F: in bacterial conjugation, all F+ donor cells are high frequency recombinant (Hfr) cells
false
T/F: vertical gene transfer is the transfer of genes from one organism to another in a population, while horizontal gene transfer is the transfer of genes from parent cell to progeny
false
a(n) ___ mutation results from an insertion or deletion of nucleotides, leading to a shift of the reading frame from the point of mutation downstream
frameshift
___ selection is used to isolate an auxotroph from a prototrophic parent strain, because no selective medium exists to inhibit the parent
indirect
occur in one or a few copies per cell
low copy number plasmids
new virus particles that have assembled in the bacterial host cell are released from that cell, usually as a result of host cell ___
lysis
sometimes the proofreading function of DNA polymerase misses errors in nucleotide incorporation. These errors are usually fixed by a mechanism called ___ repair
mismatch
genomic islands that encode disease-causing factors such as exotoxins, capsules, and adherence factors are called ___ islands
pathogenicity
random genetic changes that occur as a result of natural cellular processes are called ___ mutations
spontaneous
cells that acquire new properties as a result of the transfer of genetic material are called a) revertants b) regenerants c) replicants d) recombinants
d) recombinants
the ___ is the nucleotide sequence in the DNA of a cell or an organism, usually with reference to a specific characteristic
genotype
occur in many copies in a cell
high copy number plasmids
chromosomal DNA is transferred with F plasmid DNA in an Hfr cell because a) the plasmid DNA is integrated into the chromosome in these cells b) the chromosomal DNA is fragmented into segments c) the plasmid DNA and chromosomal DNA are similar in size d) the chromosomal DNA is homologous with plasmid DNA
a) the plasmid DNA is integrated into the chromosome in these cells
when bacillus subtillis senses that the supply of nitrogen and carbon in the environment is low a) it begins nitrogen and carbon synthesis b) it turns on genes required for competence c) it signals other cells to lyse
b) it turns on genes required for competence
mutations are rare because a) mutated DNA cannot be replicated, so it cannot be passed to progeny b) most damage is repaired before it is passed on to progeny c) damage to DNA is a very uncommon event
b) most damage is repaired before it is passed on to progeny
a ___ is a virus that infects bacteria, and can transfer bacterial genes from a donor cell to a recipient cell
bacteriophage
the easiest way to detect if streptomycin sensitive (StrS) cells are transformed with DNA from streptomycin resistant cells (StrR) is by growing the cells on a) a minimal medium like glucose salts agar b) a rich medium like TSA c) streptomycin containing medium
c) streptomycin containing medium
mutagens that are DNA segments that insert themselves into genes and inactivate them are called ___ a) intercalating agents b) alkylating agents c) transposons d) thymine dimers
c) transposons
when bacteriophages replicate, phage components are synthesized in the host cell and assemble into new viruses a) within the nucleus of the host cell before release b) after the components are released from the host cell c) within that cell before being released d) when the bacterial cell enters a new eukaryote host
c) within that cell before being released
when bacteriophages replicate, phage components are synthesized in the host cell and assemble into new viruses a) within the nucleus of the host cell before release b) within that cell before being released c) when the bacterial cell enters a new eukaryote host d) after the components are released from the host cell
b) within that cell before being released
___ ___ are molecules whose structure resembles that of nucleobases and can be mistakenly incorporated into DNA
base analogs
place the steps of F plasmid transfer in the correct order - one strand of F plasmid is cut in origin of transfer - complement of transferred strand is synthesized - single strand of F plasmid is transferred to the recipient cell - F pilus makes contact with recipient cell
- one strand of F plasmid is cut in origin of transfer - complement of transferred strand is synthesized - single strand of F plasmid is transferred to the recipient cell - F pilus makes contact with recipient cell
plasmids and chromosomes - contain an ___ of ___ - are made of ___ stranded DNA
- origin of replication - double stranded DNA
errors by DNA polymerase that incorporate the wrong nucleotide into replicating DNA can be repaired quickly by which two mechanisms - SOS repair - excision repair - mismatch repair - photoactivation - proofreading by DNA polymerase
- proofreading by DNA polymerase - mismatch repair
which of the following are methods of the introduction of new genetic information into bacteria - transduction - translation - transformation - replication - transcription - conjugation
- transduction - transformation - conjugation
examples of conditions where bacteria can become naturally competent in the environment include: - when certain nutrients are scarce - when they are exposed to extreme heat - when there is high density of bacteria - when the bacterial DNA is damaged
- when certain nutrients are scarce - when there is high density of bacteria
