quiz 7: ch 8
A _______ mutation results from an assertion or deletion of nucleotides, leading to a shift of the reading fame from a point of mutation downstream
frameshift
a ____ ____ is a large segment of a cell's genome and clearly originates in different species
genomic island
during transduction, donor DNA is injected into a recipient cell by a phage. This DNA integrates into the recipient's chromosome by
homologous recombination
the bacterial conjugation, F' donor cells are high frequency recombinant (Hfr) cells when the F plasmid _______
is integrated into the chromosome
genetic change in bacteria occurs through what two mechanisms:
mutation, horizontal gene transfer
a base substitution that changes an amino acid-encoding codon to a stop codon is called a(n) ______ mutation
nonsense
genomic islands that encode disease-causing factors such as endotoxins, capsules, and adherence factors are Called ______ islands
pathogenicity
the _____ is the observed characteristic of an organism
phenotype
______ are circular pieces of bacterial DNA that do not usually encode information essential to life of a cell
plasmids
the return of a gene from a mutated state to its original, non-mutated state is called a ______
reversion
random genetic changes that result from normal cellular processes are_______
spontaneous mutations
base _______ mutations occur when an incorrect nucleotide is incorporated in place of another during DNA synthesis
substitution
chromosomal DNA is transferred with F plasmid DNA in an Hfr cell because ______
the plasmid DNA is integrated into the chromosome in these cells
DNA-mediated ______ involves the uptake of "naked" DNA by competent bacterial recipient cells
transformation
variation in color of corn kettles was due to _____ elements
transposable
"jumping genes" or _____, can lead to changes in genotype within a cell or between cells
transposons
sequences of DNA that can move to new positions within the genome of a single cell are called
transposons
bacteriophages can consist of
-DNA genome -RNA genome -protein coat (capsid)
possible outcomes of a base substitution
-nonsense mutation -silent mutation -missense mutation
components of the simplest transposon, an insertion sequence?
-transposase gene -inverted repeats
Genomic Island
Large genomic segment in a cell's genome that originated in another species
DNA-Mediated Transformation
Mechanism of horizontal gene transfer in which "naked" DNA is taken up by the recipient cell.
Transduction
Mechanism of horizontal gene transfer in which bacterial DNA is transferred inside a phage coat.
Conjugation
Mechanism of horizontal gene transfer in which the donor cell physically contacts the recipient cell.
Phage DNA
Phage genome that sometimes carries additional genes
Homologous Recombination
Process by which a cell replaces a stretch of DNA with a segment that has a similar nucleotide sequence.
Plasmid
Replicon that is independent of the chromosome and generally encodes only non-essential genetic information
Transposon
Segment of DNA that can move from one site to another in a cell's genome.
Transposon
Segment of DNA that directs its own movement to another location in chromosomal or plasmid DNA
X rays
action: Cause single- and double-strand breaks in DNA result: Deletions
Intercalating agents
action: Insert between base pairs, pushing them apart result: Addition or subtraction of nucleotides
Transposons
action: Randomly insert into DNA result: Insertional inactivation
Ultraviolet (UV) light
action:Causes thymine dimers to form result: Errors during repair process
a _______ is a virus that infects bacteria, and can transfer bacterial genes from a donor cell to a recipient cell
bacteriophage
a bacterial cell described as _______ can take up DNA from the surrounding environment
competent
when bacteriophages replicate, phage components are synthesized in the host cell and assemble into new viruses ______
within that cell before being released
the common consequence of a ______ mutation is the appearance of an early stop codon that produces a shortened and thus non-functional protein
frameshift
the type of transduction that can transfer any genes of a host cell is called _______ transduction
generalized
once donor DNA is in a recipient cell, it integrates into that cell's chromosome by ______
homologous recombination
Plasmid
A DNA molecule that replicates independently of the chromosome.
Mutation
A change in the nucleotide sequence of a cell's DNA that is passed on to daughter cells.
Prototroph
A microorganism that does not require any organic growth factors.
Auxotroph
A microorganism that requires an organic growth factor.
Non-Homologous Recombination
DNA recombination that does not require extensive nucleotide sequence similarity in the stretches that recombine.
Horizontal Gene Transfer
DNA transfer from one bacterium to another by conjugation, DNA-mediated transformation, or transduction.
when an excision errors produces a plasmid containing both chromosomal and F plasmid DNA, the resulting plasmid is called a(n) _____ plasmid
F'
bacteria routinely adapt to new circumstances by ______
-regulating gene expression -genetic change
Phenotype
The observed characteristics of a cell.
Genotype
The sequence of nucleotides in an organism's DNA.
Vertical Gene Transfer
Transfer of genes from parent to offspring.
Base analogs
action: Base-pairing properties differ from those of nucleobases normally found in DNA result: Nucleotide substitution
Chemicals that modify nucleobases
action: Chemical modifications change base-pairing properties of nucleobases result: Nucleotide substitution
________ are an excellent model system for genetics studies because they can quickly grow to high densities, allowing us to screen for rare genetic events
bacteria
during ______ recombination, a segment of DNA inserts into the cell's genome, a process that does not quite require a similar nucleotide sequence in the region of recombination
non-homologous
the base substitution mutation leading to a stop codon is an example of a ______ mutation
nonsense
consider a population of bacteria susceptible to an antimicrobial. if a bacterium acquires a spontaneous mutation that gives resistance to the antimicrobial, this bacterium will ________ if the population is exposed to the antimicrobial
grow without competition
