Chapter 10
DNA ligase
What attaches the target gene to a desired location?
A nucleotide-altering chemical
What can alter nitrogenous bases of DNA, resulting in incorrect base pairing?
The cells have a capsule
What characteristic of the S strain allows it to evade the immune system of the mice?
It can replace the base thymine, and can base pair with guanine rather than adenine.
What describes how 5-bromouracil might create a mutation?
Stay healthy, because their immune systems can kill this strain easily
What happens to mice that are injected with only the R strain of Streptococcus pneumoniae?
Mutagen
What increases the likelihood of mutations in DNA?
F+ bacteria have a nonintegrated F plasmid, while Hfr bacteria have an F plasmid that is integrated into their main chromosome
What is the difference between an F+ and an Hfr bacterium?
Benzopyrene
What might result in a frameshift mutation?
The R strain picked up the S strain DNA, enabling it to produce a capsule
What most likely explains the recovery of live S strain cells from a mouse injected with heat-killed S strain mixed with live R strain cells?
The cells must come into contact with each other
What must occur for bacterial conjugation to take place?
Both simple and complex transposons
Which type of transposon would contain a gene for transposase?
It can be copied, transcribed, and translated into a desired protein
Why would a recombinant DNA molecule be inserted into a host cell?
transformation
genetic transfer process by which DNA is incorporated into a recipient cell and brings about genetic change
replicative
mechanism of transposition where a new copy of transposon is inserted in another location -number of transposon present doubles
conservative
mechanism of transposition where transposon is excised from one location and reinserted in second -number of transposon stays consistent
transposons
moves DNA between inverted repeats
genetic recombination
physical exchange of DNA between genetic elements
homologous recombination
process that results in genetic exchange between homologous DNA from 2 different sources
transposition
process used to move transposable elements
transposable elements
segments of DNA that move as a unit from location to another within other DNA molecules
A mutation
A change in the base sequence of DNA that is passed on to daughter cells is __________.
An auxotroph
An organism that cannot synthesize methionine is called __________.
Conjugation does not result in the formation of new offspring
Bacterial conjugation is often referred to as bacterial sex. Why is this term inaccurate?
Cas protein
CRISPER-associated protein -stores, recognizes, and destroys foreign DNA
Competent cells
Cells that can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination
generalized transduction
DNA from any portion of host genome is package inside virion
specialized transduction
DNA from specific region of host chromosome is integrated directly into the virus genome
When a frameshift mutation occurs, it causes changes in many bases downstream and can affect many of the amino acids in the protein
Frameshift mutations can be very severe. What is one reason why they are often so serious?
Complex transposons code for additional genetic elements, such as antibiotic resistance genes; simple transposons only code for the transposase gene essential for the tranposon itself
How do complex transposons differ from simple transposons?
They cut DNA at sites, called recognition sites, that have specific nucleotide sequences
How do restriction enzymes cut DNA sequences?
They differ in their genotype and in their phenotype
In a culture of bacteria, there are some individuals that are unable to synthesize histidine. What is the best and most likely description of how these individuals differ from the other bacteria in the culture?
To insert a desirable gene, remove an undesirable gene, or replace a defective gene with a functioning gene
In general, how might recombinant DNA technology be used to prevent a genetic disorder caused by a mutation in a single gene?
These bacteria may be able to adapt rapidly to a new environment (e.g., an environment with an antibiotic)
Some bacteria have unusually high mutation rates. Is there an adaptive reason why they might have such high mutation rates?
S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains
Surprising findings from Griffith's experiments?
It is important to compare the rate of mutations with the chemical to the normal background mutation rate. Mutations occur spontaneously even without the presence of a mutagen
The Ames test is commonly used to test whether a particular chemical is mutagenic. When you conduct an Ames test, you need two groups of plates. One group of plates contains bacteria that are exposed to the chemical of interest, while the other plates contain bacteria that are not exposed to the chemical. Why is the latter group needed if you are just interested in the rate of mutation caused by the chemical?
Near the beginning of the coding region of a protein
The addition of two bases to the genome of a prokaryote would be most damaging if located __________.
AUU, AUC, and AUA all code for Ile
The genetic code is degenerate. What describes an example of the degenerate nature of the code?
nonionizing radiation
Thymine dimers result from what?
phage conversion
alteration of the phenotype of a host cell by a lysogenization
CRISPER
clustered regulatory interspaced short palindromic repeats -type of prokaryotic "immune system"
transduction
transfer of DNA from one cell to another by a bacteriophage
transfection
transformation of bacteria with DNA extracted from a virus
