Microbiology (Human Pathogens) Chapter 8 Delgado
Errors by DNA polymerase that incorporates the wrong nucleotide into replicating DNA can be repaired quickly by which two mechanism
- Mismatch repair - Proofreading by DNA polymerase
place the steps of F plasmid transfer in the correct order
1)F pilus makes contact with recipient cell 2)one strand of F plasmid is cut in origin of transfer 3) single strand of the F plasmid is transferred to the recipient cell 4) complement of transferred strand is synthesized
Conjugation
A temporary union of two organisms for the purpose of DNA transfer.
________Such as E.Coli 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
chemical mutagens can cause 2 types of mutations: ________ substitution and ___________ mutations .
Base Frameshift
Bacteriophages can consist of
DNA genome RNA genome protein coat (capsid)
non-homologous recombination
DNA recombination that does not require extensive nucleotide sequence similarity in the stretches that recombine
In humans 2 of the genes associated with the development breast cancer encode enzymes involved in ___________
DNA repair
horizontal gene transfer
DNA transfer from one bacterium to another by conjugation, DNA-mediated transformation, or transduction
In bacterial conjugation, all F+ donor cells are high frequency recombinant (Hfr) cells
False
Barbara McClintock (1902-1992)
Observed that kernel colors in corn not inherited in a predictable manner • Concluded segments of DNA moved in and out of genes involved in color • Destroyed function of genes • Published results in 1950 • Met with skepticism • DNA believed stable • Idea established by 1970s • Awarded Nobel Prize in 1983 • Termed transposons • "Jumping genes"
A mutant that requires a growth factor is a
auxotroph
cells that have the ability to take up DNA from the environment are called ___________ cells
competent
The F or Fertility plasmid contains genes that are required for bacterial ___________
conjugation
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.
frameshift
which type of mutation alters the reading of a gene
frameshift
The 2 types of transduction are
generalized specialized
Which of the following terms describes the sequence of nucleotides (genetic makeup) of an organism or a cell?
genotype
Transduction
mechanism of horizontal gene transfer in which bacterial DNA is transferred inside a phage coat
DNA-mediated transformation
mechanism of horizontal gene transfer in which the bacterial DNA is transferred as "naked" DNA
A _________ is an agent that that induces changes in DNA
mutagen
an organism that has a mutation is called _______
mutant
A ________ is a change in DNA that is passed on to daughter cells.
mutation
_______is the process of by which organism better adapted to an environment reproduce at a higher rate
natural selection
A ________mutation is a base substitution that changes an amino acid encoding codon to a stop codon.
nonsense
homologous recombination
process by which a cell replaces a stretch of DNA with a segment that has a similar nucleotide sequence
Bacteria are great model systems for genetic studies because when they are grown to very high numbers in small volumes of simple media _________.
rare genetic changes that happen can be easily studied
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
mutation rates are low because proofreading and ______ mechanisms fix altered or damaged DNA before it can be passed to the progeny.
repair
The return of a gene from a mutated state to its original, non-mutated state is called a
reversion
Transposon
segments of DNA that can move from one region of DNA to another in a cell's genome
base substitution that results in a codon that still codes for the wild type amino acid is called _______ mutation
silent
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
Phenotype
the observed characteristics of a cell
DNA mediated___________ involves the uptake of 'naked' DNA by competent bacterial recipient cells.
transformation
which of the following are methods of gene transfer in bacteria
transformation transduction conjugation.
The native or wild type strain describes the typical phenotype of strains isolated from nature .
true
Which of the following types of radiation are mutagenic
ultraviolet rays x-rays
If a scientist is working with bacteria that have the typical phenotype of those isolated from nature, the bacteria are considered to be _____ type
wild
Plasmid
A DNA molecule that replicates independently pf a chromosome.
_________________ are segments of DNA that can move from one location to another in cell's genome
Transposon
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
mutant cells in bacterial cultures can be isolated by _____________ and ____________ selection methods
direct indirect
A point mutation always leads to a shift of the reading frame from the point of mutation downstream.
false
bacterial conjugation does not require contact between the 2 cells
false
Genotype
the sequence of nucleotides in an organism's DNA