MICRO MH Ch. 8
In humans, two of the genes associated with the development breast cancer encode enzymes involved in ______.
DNA repair
A bacteriophage consists of a genome made up of DNA or
RNA; protein
Extensively damaged DNA activates the
SOS
Cells that have the ability to take up DNA from the environment are called ______ cells.
competent
Which of the following plasmids are self-transmissible?
conjugative plasmids only
Conjugation in bacteria requires ______.
contact between donor and recipient cell
is the nucleotide sequence in the DNA of a cell or an organism.
genotype
Replica plating is used in ______ selection to transfer an identical pattern of bacterial cells to both a nutrient agar and a glucose-salts agar plate.
indirect
gene transfer, DNA moves from one organism to another, while in
horizontal; vertical
The process by which organisms best adapted to a given environment will predominate in that environment is called _______.
natural selection
Which of the following are possible outcomes of a base substitution?
nonsense mutation synonymous mutation missense mutation
Which type of DNA repair is shown in this figure?
nucleotide excision repair
Donor and recipient bacterial cells are connected by a sex ______ during conjugation.
pilus
______ are segments of DNA that can move from one location to another in a cell's genome.
Transposons
Which of the following types of radiation are mutagenic?
Ultraviolet rays X-rays
The structure connecting these two cells is called an F
pilus conjugation
The type of DNA damage repair illustrated here is _______.
base excision repair
When describing conjugation in Gram-negative bacteria, a donor cell with an F ______ is considered F+, while that without this structure are termed F-.
plasmid
Chemicals that cause cancer are known as ______, and most of them are ______.
carcinogens; mutagens
Random genetic changes that result from normal cellular processes are ______.
spontaneous mutations
A base substitution that results in a codon that still codes for the wild type amino acid is called a(n) ______ mutation.
synonymous
True or false: A point mutation involves any substitution of a single nucleotide.
t
True or false: Incorporation of an incorrect nucleotide in a molecule of DNA results in a distortion of the DNA helix that can be detected by repair enzymes.
t
True or false: The native or wild type strain describes the typical phenotype of strains isolated from nature.
true
Recognition and repair of errors in nucleotide incorporation by DNA polymerase is called ______.
proofreading
The process of bacterial
transformation
Place the steps of DNA-mediated transformation into the correct order. Start with the earliest at the top.
1. Double 2.nucleases 3. single 4.strand
When bacteriophages replicate, phage components are synthesized in the host cell and assemble into new viruses ______.
within that cell before being released
______ is used to fix nucleotide incorporation errors that are missed by the proofreading function of DNA polymerase.
Mismatch repair
transduction results from a packaging error during the virus replication cycle, when a piece of bacterial DNA is included in the new virus particle.
Generalized
This figure depicts the interconversion between an F+ cell and a(n)
Hfr
structurally resemble nucleobases and can be mistakenly used when cells make nucleotides, which are then incorporated by DNA polymerase into DNA.
base analogs
A plasmid that can directs its own transfer from donor to recipient cells is called a(n)
conjugative
Ultraviolet radiation causes covalent bonds to specifically form between adjacent
thymine
Ultraviolet radiation causes a very specific type of DNA damage called ______.
thymine dimers
mutation occurs if a single base pair is changed during DNA synthesis.
point
is the change of a mutated genetic sequence back to its original, non-mutated form.
reversion
The most common type of mutation is base
substitution
Which of the following statements about transformation is correct?
Transformation is the uptake of naked DNA from the environment.
In conjugation in E. coli, an Hfr cell refers to ______.
a cell in which the F plasmid has been integrated into the cell chromosome
Which of the following are caused by chemical mutagens?
frameshift mutations base substitutions
is a change in the nucleotide sequence of DNA that is passed on to daughter cells.
mutation
Genetic change in bacteria occurs through which two mechanisms?
mutation horizontal gene transfer
is the observed characteristics of an organism.
phenotype
When horizontal gene transfer occurs between a donor and recipient cells, the resulting cells are called
recombinants
Base ______ mutations occur when an incorrect nucleotide is incorporated in place of another during DNA synthesis.
substitution
Chemical mutagens can cause two types of mutations:
base; frameshift
There are two types of transduction:
generalized specialized
Chemical mutagens that modify ______ increase the odds of incorrect nucleotide incorporation during DNA replication.
nucleobases
A bacterial virus is known as a(n) _______.
phage
Which of the following can be found in a bacteriophage?
protein coat DNA or RNA genome
In the most thoroughly studied example of bacterial conjugation, the term
F+ F-
Which of the following are characteristics of recombinants?
The have properties of both donor and recipient cells. They result from horizontal gene transfer.
Mutations that arise naturally during cellular metabolism, and not as a result of exposure to mutation-causing agents, are called
spontaneous
Mutations that are caused by external influences such as radiation or chemicals are called ______ mutations.
induced
Plasmids, transposons and phage DNA are all examples of ______.
mobile genetic elements
The consequences of not repairing damaged DNA in cells include ______.
cell death cancer (in animals)
Mutant cells in bacterial cultures can be isolated by
direct; indirect
Cancer-causing chemicals are called
carcinogens
In bacteria
conjugation
mutations are genetic changes caused by factors from outside of the cell such as radiation or chemicals.
induced
are DNA segments that increase the rate of mutations by inserting themselves into genes and inactivating them.
transpoons
Organisms most fit to survive in a given environment will predominate because they can reproduce more rapidly than others. This phenomenon is called
natural selection
After new virus particles have assembled in the bacterial host cell, they are usually ______.
released as a result of host cell lysis
Mutagens that modify nucleobases change their
base; pairing
A bacterial cell described as
competent
The return of a gene from a mutated state to its original, non-mutated state is called a ______.
reversion
Plasmids that encode resistance to a variety of antimicrobial agents and heavy metals are called
R
Errors by DNA polymerase that incorporate the wrong nucleotide into replicating DNA can be repaired quickly by which two mechanisms?
Mismatch repair Proofreading by DNA polymerase
Protection against the toxic effects of antimicrobial compounds or heavy metals is often encoded on plasmids called
R
Mutants that can grow under conditions in which the parent (wild type) cells cannot are easily isolated by
direct
Two methods used to identify mutants in a culture are ______ and ______ selection.
direct; indirect
Low copy number high copy number narrow host range broad host range
occur in one or a few omccur in many can replicate in only can replicate in many
Which of the following are examples of mobile genetic elements?
phage DNA genomic islands transposons plasmids
Plating bacteria in duplicate patterns on both a nutrient agar plate and a glucose-salts agar plate is an example of
replica
An origin of transfer is encoded by _______.
both conjugative and mobilizable plasmids
Contains an origin of replication made of double stranded RNA typically do not encode genes essential to the life of the cell found in all eukaryotes and prokaryotes
both plasmids and chromosomes neither plasmids nor chromosomes plasmids only chromosomes only
During bacterial conjugation, synthesis of a new strand of F plasmid DNA occurs in ______.
both the donor and recipient
Although mobilizable plasmids encode an origin of transfer, they lack other genetic information required for transfer. Under what circumstances can a mobilizable plasmid be transferred to another bacterial cell?
when a conjugative plasmid is present in the same cell
During repair of oxidized guanine, which enzyme removes the damaged nucleobase from the sugar-phosphate backbone?
DNA glycosylase
In prokaryotes, genes can be transferred from a donor to a recipient via three different mechanisms:
transformation transduction conjugation
When an excision errors produces a plasmid containing both chromosomal and F plasmid DNA, the resulting plasmid is called a(n)
F prime
When integrated F plasmid DNA in an Hfr cell is excised from the chromosome, an excision error can result in the removal of chromosomal DNA along with the F plasmid DNA, creating a plasmid called ______.
F'
In bacteria,
conjugation
is a virus that infects bacteria, and some can transfer bacterial genes from a donor cell to a recipient cell.
bacteriophage
Which of the following describes an organism's observable characteristics?
phenotype
Many DNA polymerases have the ability to detect and repair their own errors in nucleotide incorporation. This ability is called
proofreading
Segments of DNA that can move to new positions within the genome of a single cell are called
transposons
selection is used to isolate an auxotroph from a prototrophic parent strain, because no selective medium exists to inhibit the parent.
indirect
______ sometimes incorporates the incorrect nucleotide when generating a new strand of DNA during DNA ______; this leads to a detectable distortion in the DNA helix.
DNA polymerase; replication
True or false: 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.
F
An auxotroph can be isolated from a prototrophic parent strain by ______ selection.
indirect
In transformation, only one daughter cell inherits donor DNA. This is because ______.
only a single strand of donor DNA integrates into the recipient chromosome
Mutagens that are DNA segments that can insert into genes and thereby inactivate them are called ______.
transposons
are circular pieces of bacterial DNA that do not usually encode information essential to the life of a cell.
Plasmids
______ repair is activated by extensive DNA damage and uses a polymerase that lacks proofreading ability, ultimately resulting in mutations.
SOS
This figure shows the steps of ______, a process that repairs thymine dimers by breaking the covalent bonds that have formed between adjacent thymines.
photoreactivation
An organism that has a mutation is called a
mutant
Which term refers to an organism that has a mutation?
mutant
Which of the following plasmids encodes all the necessary genetic information for transfer from one bacterial cell to another?
Conjugative plasmids only
In E. coli, less than 50% of the genes are found in all strains. These conserved genes are called the
core
The genes that are present in all strains of a given species are called the ______.
core genome
Which of the following terms describes the sequence of nucleotides (genetic makeup) of an organism or a cell?
Genotype
mutation is a base substitution that does not change the encoded amino acid.
silent
The mechanism by which bacterial DNA is moved from one bacterium to another by a bacteriophage is called
transduction
The genetic transfer mechanism shown here is called
transformation
Which of the following are the three main methods of gene transfer in bacteria?
transformation conjugation transduction
The native or
wild type
True or false: In bacterial conjugation, all F+ donor cells are high frequency recombinant (Hfr) cells.
False
True or false: Plasmids are insertion sequences that can lead to changes in genotype within a cell or between cells.
False
Place the steps of F plasmid transfer in the correct order. Start with the earliest at the top.
1. f 2. o 3. s 4. c
_______ is the transfer of bacterial DNA from a donor to recipient via a bacteriophage.
Transduction
Which mechanism of gene transfer involves the uptake of "naked" DNA by competent bacterial recipient cells?
Transformation
Base ______ structurally resemble nucleobases and can be mistakenly incorporated into nucleotides and then into DNA.
analogs
True or false: A point mutation always leads to a shift of the reading frame from the point of mutation downstream.
f
True or false: Ultraviolet rays are chemical mutagens.
f
mutation results from an insertion or deletion of nucleotides, leading to a shift of the reading frame from the point of mutation downstream.
frameshift
The type of transduction that can transfer any genes of a host cell is called ______ transduction.
generalized
Plasmids with a
low; high
A base substitution that results in a change in the amino acid encoded is called a(n) ______ mutation.
missense
mutation is a base substitution that changes the codon to one that specifies a different amino acid.
missense
A base substitution in a protein-encoding gene results in one of three possible mutation outcomes:
silent; missense; nonsense
Transduction exists in two kinds. What are they?v
specialized generalized
The F or fertility plasmid contains genes that are required for bacterial ______.
conjugation
Selecting penicillin-resistant mutants by plating them on a medium containing penicillin is an example of ______ selection.
direct
This figure shows a cell with an integrated F plasmid. If this plasmid is incorrectly excised, the result could be an F plasmid that carries along a portion of the bacterial chromosome. Such a cell would then be called a(n)
F prime
Repair of nucleotide incorporation errors during the process of DNA replication is accomplished by
proofreading; mismatch
