Microbiology Chapter 8 Terms & Questions
Mutant cells in a bacterial culture can be identified by _____________ and _________ selection methods.
direct; indirect
Resistance, or R, plasmids
encode resistance to many different antimicrobial medications and heavy metals, such as mercury and arsenic, all of which are found in hospital environments.
R genes
encode resistance traits
RTF
encodes properties needed for conjugation
Horizontal transfer
from one organism to another in a population
Vertical transfer
from parent to offspring
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
The modified organism and daughter cells
mutants
The two mechanisms (sources of genetic change in bacteria are _______ and ________ gene transfer
mutation; horizontal
DNA in the environment that is contained within a cell or virus is called _________ DNA.
naked
In this image, the base substitution labeled as "Mutation C" is called a(n) __________ mutation.
nonsense (SEE PICTURE IN MICRO FOLDER ON LAPTOP)
In bacterial conjugation, F+ donor cells are high frequency recombinant (Hfr) cells when the F ______ is integrated into the chromosomes.
plasmid
Repair of nucleotide incorporation errors during the process of DNA replication is accomplished by _____________ by DNA polymerase and by __________ repair.
proofreading; mismatch
Protection against the toxic effects of antimicrobial compounds or heavy metals is often found to be encoded on _______ plasmids.
resistance or R
Indirect selection
used to isolate an auxotrophic mutant from a prototrophic parent strain
The consequences of not repairing damaged DNA in cells include: A) cell death B) cells that have less mutations C) cancer (in animals)
A) cell death C) cancer (in animals)
The type of transduction that can transfer any genes of a host cell is called _______ transduction. A) generalized B) specialized C) randomized D) localized
A) generalized
___________ 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
A point mutation always leads to a shift of the reading frame from the point mutation downstream. A) True B) False
B) False
Which of the following types of radiation are mutagenic? A) Infrared rays B) Ultraviolet rays C) X-rays
B) Ultraviolet rays C) X-rays
Bacteria routinely adjust to new circumstances by: A) endospore formation B) regulating gene expression C) genetic change
B) regulating gene expression C) genetic change
Chromosomes
Cells cannot survive their loss & Found in all eukaryotes and prokaryotes
Mutation rates are low because proofreading and __________ mechanisms fix altered or damaged DNA before it can be passed to progeny.
DNA repair
carried on mobile genetic elements including various plasmids, transposons, regions called ________.
Genomic islands
A(n) ____________ is a large segment of a cell's genome that has clearly originated in a different species.
Genomic islands;
Direct selection
Mutants that grow under conditions in which the parent cells cannot are usually easy to isolate
__________ are circular pieces of bacterial DNA that do not usually encode information essential to the life of a cell.
Plasmids
mobile gene pool
These genes can move from one DNA molecule to another,
If a scientist is working with a bacterium that has the typical phenotype of strains isolated from nature, that bacterium is called _____ type.
wild
Which of the following are replicons? A) plasmid B) chromosome C) chromosome fragment
A) plasmid B) chromosome
Which of the following can be transferred from one cell to another by conjugation? A) Phage DNA B) Plasmid DNA C) Bacterial RNA D) Bacterial proteins E) Chromosomal DNA
B) Plasmid DNA E) Chromosomal DNA
The two types of transduction are: A) specific B) generalized C) localized D) specialized E) filamentous
B) generalized D) specialized
An auxotroph can be isolated from a prototrophic parent strain by _________ selection. A) direct B) degenerate C) indirect D) differential
C) indirect
Plasmids
Typically do not encode genes essential to the life of the cell & Often the location of antibiotic resistance genes in bacteria
A bacteriophage consists of a(n) __________ coat that surrounds the nucleic acid __________.
protein; genome
Genetic change in bacteria occurs through which two mechanisms? A) horizontal gene transfer B) vertical gene transfer C) mutation
A) horizontal gene mutation C) mutation
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. A) True B) False
B) False
Which of the following mutations frequently results in the production of a shortened and non-functional protein because a different set of codons is translated? A) Missense B) Frameshift C) Point D) Silent E) Base substitution F) Nonsense
B) Frameshift
Which of the following are methods of the introduction of new genetic information into bacteria? A) Translation B) Transformation C) Transduction D) Conjugation E) Transcription F) Replication
B) Transformation C) Transduction D) Conjugation
If a bacterial cell spontaneously mutates to become resistant to an antimicrobial drug, this bacterium will _____________ when the antimicrobial drug is present. A) not grow as well as all the other bacteria B) grow without competition C) grow as well as all the other bacteria
B) grow without competition
Which of the following are possible outcomes of a base substitution? A) frameshift B) thymine dimer mutation C) silent mutation D) nonsense mutation E) missense mutation
C) silent mutation D) nonsense mutation E) missense mutation
The two mechanisms (sources) of genetic change in bacteria are __________ and ___________ gene transfer.
mutation; horizontal
Recognition and repair of errors in nucleotide incorporation by DNA polymerase is called ________.
proofreading
DNA-mediated Transformation
"Naked" DNA is taken up from the environment by a bacterial cell.
Place the steps of F plasmid transfer in the correct order. Single strand of F plasmid is cut in origin of transfer. Complement of transferred strand is synthesized. F pilus makes contact with recipient cell. Single strand of F plasmid is transferred to the recipient cell.
1 - F pilus makes contact with recipient cell 2 - One strand of F plasmid is cut in origin of transfer 3 - Single strand of F plasmid is transferred to the recipient cell 4 - Complement of transferred strand is synthesized
Plasmids and Chromosomes
Contains an orgin of replication & Made of double stranded DNA
Which of the following can be transferred from one cell to another by conjugation? A) Genotype B) Serotype C) Haplotype D) Phenotype
D) Phenotype
Selecting penicillin-resistant mutants by plating them on a medium containing penicillin is an example of ___________ selection. A) differential B) indirect C) degenerate D) direct
D) direct
The return of a gene from a mutated state to its original, non-mutated state is called a __________. A) repression B) recombination C) regression D) reversion E) revision
D) reversion
Conjugation
DNA is transferred during cell-to-cell contact; a complex process that requires contact between donor and recipient bacterial cells.
Transduction
DNA is transferred from one bacterial cell to another by a bacteriophage (a virus that infects bacteria).
High-copy-number plasmids
Occur in many copies in a cell
Low-copy-number plasmids
Occur in one or a few copies per cell
Match each statement with the correct nucleic acid molecule (ADD 1-3 with A-F put A-F in the correct category) 1 - Plasmids and Chromosomes 2 - Plasmids 3 - Chromosomes A) Cells cannot survive their loss B) Typically do not encode genes essential to the life of the cell C) Contains an orgin of replication D) Often the location of antibiotic resistance genes in bacteria E) Made of double stranded DNA F) Found in all eukaryotes and prokaryotes
Plasmids and Chromosomes - C & E Plasmids - B & D Chromosomes - A & F
Horizontal gene Transfer
Transfer of DNA from a source other than the parent organisms; the movement of DNA from one organism to another.
Vertical gene transfer
Transfer of DNA from parent organisms during reproduction; The movement of genetic information from parent to daughter cells and is not a source of genetic change
__________ are DNA segments that increases the rate of mutations by inserting themselves into a gene and inactivating it.
Transposons
reversion
a mutation will change back to its orginal, non-mutated state
Induced mutations
are genetic changes caused by factors from outside of the cell such as radiation or chemical changes
Genomic islands
are large DNA segments in a cell's genome that originated in other species.
Replicon
it has an origin of replication
New virus particles that have assembled in the bacterial host cell are released from that cell, usually as a result of host cell _________.
lysis
wild type
the typical phenotype of strains isolated from nature
Most transposons contain _______________ terminators
transcriptional
Plasmids are insertion sequences that can lead to changes in genotype within a cell or between cells. A) True B) False
B) False
Broad host range
Can replicate in many different species
Narrow host range
Can replicate in only one species
The native or _______ ______ strain describes cells that carry non-mutated DNA.
wild type
Which of the following results in the production of a shortened and non-functional protein? A) Frameshift B) Silent C) Missense D) Base substitution E) Point F) Nonsense
A) Frameshift F) Nonsense
X-rays can cause which types of damage to a DNA molecule? A) Nucleobase alterations B) Double stranded breaks C) Single stranded breaks D) Thymine dimer formation
A) Nucleobase alterations B) Double stranded breaks C) Single stranded breaks
Bacteriophages can consist of: A) Protein coat (capsid) B) DNA genome C) Membrane (envelope) D) Nucleus E) RNA genome F) Hybrid DNA/RNA genome
A) Protein coat (capsid) B) DNA genome E) RNA genome
A point mutation involves any substitution of a single nucleotide that does not change the DNA reading frame A) True B) False
A) True
Plasmids are small, usually circular pieces of DNA that contain their own orgin of replication. A) True B) False
A) True
The two types of transduction are: A) generalized B) specific C) specialized D) filamentous E) localized
A) generalized C) specialized
___________ are random genetic changes that result from normal cellular processes. A) Induced mutations B) Spontaneous mutations C) Silent mutations
B) Spontaneous mutations
Cells that have the ability to take up DNA from the environment are called _________ cells. A) immunogenic B) competent C) recombinant D) pathogenic
B) competent
Chemical mutagens can cause which of the following? A) base substitutions B) frameshift mutations C) double stranded breaks D) thymine dimers
A) base substitutions B) frameshift mutations
Place the steps of DNA-mediated transformation into the correct order. Nucleases degrade one strand of double-stranded DNA at the cell surface. Single-Stranded DNA enters cell after one strand has been degraded. Double-stranded DNA molecule binds to surface receptor. Single-stranded DNA integrates into genome after entering the cell.
1) Double-stranded DNA molecule binds to surface receptor. 2) Nucleases degrade one strand of double-stranded DNA at the cell surface. 3) Single-Stranded DNA enters cell after one strand has been degraded. 4) Single-stranded DNA integrates into genome after entering the cell.
Base ________ structurally resemble nucleobases and can be mistakenly incorporated into nucleotides and then into DNA. A) analogs B) donors C) pairs D) adapters
A) analogs
