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