Ch 8 pearson
Think about the process of DNA replication, the enzymes involved in the process, and the results of the process.
-DNA replication provides an exact copy of DNA for daughter cells (next generation). -DNA replication occurs prior to mitosis and prior to binary fission. -The major replication enzyme is DNA polymerase -Topoisomerase and DNA gyrase remove supercoiling ahead of the replication fork. -DNA replication can copy plasmids, which can be transferred among bacterial cells of the same generation. -DNA replication is semiconservative. -DNA helicase separates the DNA strands, creating a replication fork.
A strain of Neisseria gonorrhoeae that was formerly sensitive to penicillin has recently acquired the ability to produce penicillinase, an enzyme that inactivates penicillin. Evidence indicates that this is not a new mutation but rather a gene received from another bacterium. The gene is now spreading rapidly among the population, causing the recipient bacteria to be resistant to penicillin. Place the following steps in the order in which they most likely occurred to result in the production of penicillinase.
-Transformation introduced the penicillinase gene to this strain of Nesisseria gonorrhoeae -Recombination occurred, placing the penicillinase gene in the Neisseria gonorrhoeae genome. The penicillinase gene was replicated along with all of the other DNA prior to cell division, resulting in the vertical trnasnmission of the gene to daughter cells. -The penicillinase gene was transcribed into mRNA -The penicillinase mRNA was translated into the protein penicillinase
During elongation, how is the RNA synthesized?
5' to 3'
Which of the following is NOT an example of horizontal gene transfer?
A bacterium passes a mutated gene to its offspring via binary fission
What kind of bond is formed when two amino acids join together?
A peptide bond
A bacterial strain undergoes a chromosomal mutation that converts one of its genes to a resistance gene. Later, you discover that some members of this strain now carry the gene on a plasmid. Which of the following do you think accomplished this transfer?
A transposase
Which of the following is a characteristic of an F+ cell?
Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell.
Why does conjugation between an Hfr strain and an F- strain not result in two Hfr strains?
Conjugation is typically disrupted before the fertility factor can be transferred.
Which of the following DNA sequence best represents a mutation of this sequence: 5' - TACGTAGCA - 3'?
DNA: 5' - TACCTAGCA - 3'
How is generalized transduction different from specialized transduction?
Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage.
How does an F+ cell differ from an Hfr cell?
Hfr strains have the F plasmid integrated into the chromosome.
A. baumannii became resistant to tetracycline by acquiring an R plasmid. Which of the following best describes how A. baumannii obtained this R plasmid?
Horizontal gene transfer
Where would one find an uncharged tRNA molecule in a ribosome?
In the P and E sites
What benefit does the F- strain receive from mating with an Hfr strain?
It acquires new, potentially beneficial genes from the Hfr strain
Which of the following options is a signature symptom of necrotizing fasciitis?
Loss of tissue around a wound
What is considered to be the average natural mutation rate that occurs during DNA replication?
One in every billion nucleotides replicated.
How frequently do silent mutations occur?
One out of every three mutations
How does the ribosome know if the entering charged tRNA is correct?
The anticodon on the tRNA base pairs to the codon on the mRNA.
With which genetic region does the repressor protein interact?
The operator region
What is the basic function of the lac operon?
To code for enzymes involved in catabolizing lactose.
What are the two steps A. baumannii uses to produce proteins from DNA?
Transcription and translation
Sort the following items according to whether they are associated with transcription, translation, both, or neither.
Transcription: RNA polymerase, DNA, ribonucleotides, promoter Translation: codon and anticodon pairing, ribosome, amino acids Both transcription and translation: mRNA and tRNA Neither transcription and translation: DNA polymerase, deoxyribonucleotides
What is unique about transduction compared to normal bacteriophage infection?
Transduction transfers DNA from the chromosome of one cell to another.
Drag the statement to the gene transfer mechanism with which it is associated. A statement may be associated with more than one mechanism.
Transformation: Extracellular DNAases would block this transfer mechanism. -This mechanism was first explored by Griffith as he studied smooth and rough strains of Streptococcus pneumoniae. Conjugation: This mechanism is initiated by cells with F plasmids. -This mechanism requires cell-to-cell contact. -A chemical that blocked the formation of a pilus would block this genetic transfer mechanism. Transduction: A virus that infects bacteria is a key component in this transfer mechanism. All mechanisms: This mechanism of genetic transfer always involves a one-way transfer from a donor cell to a recipient cell. -This mechanism may result in the transfer of genes that encode antibiotic resistance.
How is translation terminated?
When a protein called a release factor enters and binds to the A site
What is the inducer molecule in the lac operon?
allolactose
A transducing phage
contains fragments of the host chromosome instead of the viral genome.
A base insertion or deletion in the translated region of the gene may lead to
frameshift mutation
How would one increase the concentration of a particular polypeptide in a cell?
increase the level of transcription
Part complete A base substitution that changes a codon coding for an amino acid to a stop codon is called a
nonsense mutation
During the initiation step of translation, the fMet charged tRNA assembles in which site of the ribosome?
p site
What is the initial target of RNA polymerase?
promoter
A mutation that affects the genotype of the organism but not the phenotype is called a
silent mutation
RNA that has hydrogen bonded to itself forms a
stem loop
RNA polymerase is guided by the
template strand of DNA.
When a transducing phage interacts with a new host cell,
the DNA from the previous host can recombine with the new host chromosome.
According to the animation, to what genetic element does the RNA polymerase bind?
the promoter
When the cell is not in the presence of lactose,
the repressor proteins bind to the operator.
