The flashcards below were created by user
BrookeNH10
on FreezingBlue Flashcards.
-
Bacterial chromosome
Circular dsDNA
-
Bacteiral plasmid
Circular dsDNA
-
Allows coordinated production of proteins to respond to a stimulus.
Operon
-
-
Protein nomenclature
DnaA
-
Pathogenicity Islands
1) Large genomic regions that carry one or more ___
2) ____ different from rest of genome
3) Mechanism for mobilization
- 1) virulence factors
- 2) %G+C
-
Bacterial replication is ________ and _______.
May have several______
- Semi-conservative, bi-directional
- Can have several replication forks
- There are no visibly condensed chromosomes
-
Replication is initiated at:
Origin of replication in the chromosome?
Origin of replication in the plasmid?
Ends at terminus?
- Chromosome = oriC
- Plasmid= oriV
- Terminus= ter
-
What enzyme releaves supercoiling?
What antibiotics target these enzymes?
Topoisomerase relieves supercoiling and is the target of quinolone antibiotics.
-
Bacterial replication requires 4 enzymes. What are they and what do they do?
- Helicase
- Primase
- DNA Polymerase
- Topoisomerase
-
What enzyme is required for bacterial transcription?
What antibiotic targets this enzyme?
- RNAP: RNA Polymerase
- Rifampin
-
Bacterial genes that are going to be transcribed are specified by what factor of RNA Polymerase?
- Sigma factor
- Different sigma factor recognize different promoters, coordinate multiple different operons
-
70S ribosome subunit is target of many antibiotics. Name them.
Aminoglycosides, tetracyclines, macrolides, lincosamides, oxazoldinones, etc.
-
What is two processes of the central dogma are coupled in bacteria since they are not compartmentalized like eukaryotes?
Transcription and translation are coupled in bacteria.
-
Most important level of gene regulation in bacteria?
Transcription
-
Genes are expressed unless switched off by a repressor protein which binds to operator.
- Negative control
- (Bla1 binds operator in absence of penicillin preventing synthesis of Beta-lactamase)
-
Genes are not transcribed unless an active regulator protein is present.
Positive control
-
Accessory Gene Regulator (agr) of Staphylococci:
1) Consists of:
2) Affects? Up-regulates? Down-regulates?
3) Facilitates switch from ____ to _____ state.
- 1) Two-Component Regulatory System (TCS) & Quorum-Sensing System (QS)
- 2) Affects expression of most known virulence factors. Up-regulates- genes w/ extracellular produces. Down-regulates- genes w/ surface-associated products
- 3) adhesive--> invasive state
-
Quorum-Sensing System (QS) responds to
Cell density
-
Which portion of the agr includes a histidine kinase and a response regulator (AgrC, AgrA)?
Two-component regulatory system
-
Which portion of the agr contains a signal molecule (AgrD)?
QS
-
The agr in gram-P cells signal with ______
peptide signals
-
The agr in Gram-N cells signal with
Homoserine lactone chemical signals
-
What is the ultimate source of genetic variation in bacteria?
Mutations
-
Deamination involves a switch of
C--> U --> T
-
Purine <-> Purine
Pyrimidine <-> Pyrimidine
Transition
-
Purine <-> Pyrimidine
Transversion
-
Transitions or transversions, which are more common?
Transitions (they don't distort the DNA double helix as much)
-
Mutations in which codon position are often silent?
3rd
-
Slippery Sequences
Short repetitive sequences that cause problems for DNA Polymerase during replication. Result in slipped-strand mispairing.
-
Antigenic variation in Neisseria gonorrhoeae
PorB (encoded by PIA and PIB) exposed at different levels.
-
MDR-TB is defined as having resistance to?
- 2 first-line drugs
- Arises from step-wise accumulation of mutations combined w/ antibiotic selection
-
Most effective drug for TB tx?
It is a pro-drug activated by?
- Isoniazid (disrupts synthesis of mycolic acids)
- Activated by catalase enzyme KatG
-
Breakage and rejoining of two DNA molecules in new combiantions?
Recombination
-
What type of recombination requires longer regions of similarity between the two DNAs?
Homologous recombination
-
Homologous recombination is mediated by what enzyme?
RecA enzyme
-
What type of recombination requires shorter regions of similarity or no similarity at all?
Nonhomologous recombination
-
Nonhomologous recombination is mediated by what enzymes?
- DDE transposaes
- Site-specific recombinases
-
Intracellular horizonal genetic transfer is accomplished by?
Transposition via transposons
-
Intercellular genetic transfer is accomplished by?
- Conjugation (via plasmids)
- Transformation (via "naked" DNA)
- Transduction (via phage)
-
Segments of DNA that are able to move from one replicon to another within a cell?
Transposons
-
Transposon that consists of transposase and associated repeat sequence?
Insertion Sequences (IS elements)
-
Transposon: Consits of two IS elements plus any DNA btw them and associated repeated sequences.
Composite transposon (Tn)
-
Tranposon: Consists of a transposase, a resolvase, other genes (cargo), and associated repeat sequences.
Replicative transposons (Tn)
-
Simple Transposition:
What is it?
Requires activity of what type of enzyme?
Only target DNA gets the transposon
- "Cut & Paste"
- Requires activity of transposase
-
Replicative Transposition:
What is it?
Requries activity of?
Both donor and target DNA get transposon (one DNA strand moves)
- "Copy & Paste"
- Requires activity of transposase and resolvase (separates a single circular molecule into two circular molecules)
-
Conjugative plasmids:
Self-transmissable or not self-transmissible?
Encodes 15-35 ___ genes w/ ___ and ___ fxns
Example: F-plasmid
- Self-transmissable
- Encodes 15-35 tra genes w/ Mpf and Dtr fxns
-
Mpf fxns
Makes cell to cell contact via pilus (type 4 SS in gram-N) or via aggregation (gram-P)
-
Dtr fxns
Forms relaxosome, enables circle replication at oriT
-
Mobilizable Plasmids:
Self-transmissable or not self-transmissible
Dtr fxns are encoded by ___ genes instead of ___ genes
- Not self-transmissible (lack Mpf genes)
- Dtr fxns are encoded by mob (mobilization) genes instead of tra genes
-
3 Types of Bacterial Plasmids
- Conjugative Plasmids
- Mobilizable Plasmids
- Non-mobilizable plasmids
-
Conjugative pilus is what type of secretion system?
Type 4 Secretion System
-
Translocation of DNA requires?
ATP
-
Types of Conjugation? What do they do?
- 1) F Plasmid Conjugation: F+ donor (male) converts an F- recipient (female) into an F+ cell
- 2) Hfr (High Frequency Recombination) Conjugation: F plasmid is integrated into the donor's chromosome via homologous recombination. A portion of the donor's chormosome replaces the recipient's chromosome, no conversion of recipient to F+.
-
What does a plasmid need to be considered mobilizable?
oriT
-
Conjugative transposons (normally integrated into a chromosome or plasmid):
Combine features of transposons and conjugative plasmids (maintained by replication like transposons, transferred like conjugative plasmids)
1) How are they different from a classical transposon?
2) When do they replicate? How about once they're in their target genome?
- 1) Intercellular transposition
- 2) Replicate only during the conjugation process until they're in their target genome. Then they replicate like other DNA.
-
Conjugative transposons are highly promiscuous.
Donor and recipient strains don't need to be the same species or even the same genus!
|
|