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28 Cards in this Set
- Front
- Back
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What are pieces of extrachromosomal DNA, small circular dsDNA that exist independently of the bacterial chromosome?
How do these elements replicate and what do they carry? What do these elements encode for? |
Plasmids
replicate autonomously in the cytoplasm and have been observed to carry a variety of genetic markers. Some of these elements encode for the expression of toxin molecules, antibiotic resistance mechanisms, hydrocarbon utilization degradative pathways, generally carry only a few genes. |
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How many plasmids are in bacteria?
How much of the total cellular DNA do they represent? When did plasmids come about & for what reason? |
Bacteria contain several
1 to 2% Came about in late 60s for antibiotic development and advanced biotechnology |
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How can you view plasmids in agarose gel? Describe the process
How do plasmids relate to copy number? |
Agarose gel can be used to view plasmids
-grow bacteria overnight on broth media, then lysis protocol -isolating both chromosomal and plasmid DNA -view gel bands -antibiotic resistant plasmids are vectors smaller the plasmid, the higher the copy number. |
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2 classes of plasmids, BLANK and BLANK, ie BLANK and BLANK
BLANK plasmids carry a sequence of genes called BLANK for transfer, involved with conjugative transfer. Genes in the BLANK region are associated with... |
conjugative and nonconjugative; transferable and non transferable.
Conjugative; tra; tra; cell attachment and plasmid transfer between bacteria. |
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What is a large conjugative plasmid that encodes for a sex pilus in E. coli?
Name two plasmids that also have tra genes (full name) What are antibiotic resistant plasmids called? Name an example |
F (fertility) plasmid
NAH plasmid: naphthalene & RP1: antibiotic resistant plasmid R plasmids; Ex: R1 |
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Some plasmids will integrate into...
What are toxins produced by bacteria to kill other related bacteria called? |
the bacterial chromosome
Bacteriosins |
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How do nonconjugative plasmids mobilize?
They usually come across with... |
mobilized via mob genes that take advantage of the transfer genes on a conjugative plasmid.
the conjugative plasmid. |
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Bacteria can express antimicrobial resistance by the expression of BLANK genes and BLANK encoded genes.
Name an example of this. |
chromosomal & plasmid (R plasmids)
Ex: In Pseudomonads, carbenicillin can expressed chromosomally and also on a plasmid. |
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Usually antibiotic genes are transferred in nature via BLANK contact or BLANK.
Where and when were R plasmids discovered? |
cell to cell or conjugation
R plasmids discovered in Shigella infection in Japan in 1960s. |
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Two features to the R plasmids, BLANK genes and BLANK genes. The BLANK genes are usually placed on the R plasmid from BLANK.
Multiple resistance plasmids are the problem in medicine today. Name an example. What is the general trend in medicine because of R plasmids? |
tra; resistance; resistance; transposons (jumping genes)
For example R1, encoding for Ap, Km, Su, Cm, Sm. multiple antibiotics are given to eliminate the infection from the patient. |
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Where did the antimicrobial genes originate?
Resistance genes are usually produced in bacteria that produce the antimicrobial, otherwise... This is true even for what bacterial toxins (peptide antimicrobials)? |
antimicrobial genes are believed to have originated even before antibiotics were discovered
It would be a fatal event for the producing strain. Bacteria with bacteriosins |
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How soon did antimicrobial resistance appear?
Name an example |
In the middle 1970’s resistance was appearing
β lactamase genes appeared in Neisseria gonorrhoeae. Penicillin r (1970s), tetracycline r (1980s), and ciprofloxacin r (2000s), resistant strains |
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Some plasmids encode for BLANK pathways or the BLANK of specific hydrocarbons.
Name some examples Some plasmids encode for the production of BLANK, where are proteins that kill bacteria that are closely related or occupy the same niche. Name an example Some plasmids encode for resistance to heavy metals such as... |
metabolic; degradation
Ex: NAH, TOL, and SAL, and pJP4. bacteriocins Ex: colicin plasmids, Col. Silver and copper |
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Plasmids that remain separate AND integrate into the chromosome are called BLANK. Integration is generally...
The integration of these genes into the chromosome reduces their copy number because... |
Episomes; stable
plasmids exist in multiple copies in the cell whereas the chromosome has 1 copy. |
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What is plasmid curing?
It works by... Curing used to determine what a plasmid... |
The removal of plasmids from the cell, via treatment with acridine orange (AO) or temperature.
Interfering with plasmid replication. encodes for |
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How is plasmid incompatibility determined?
Many different incompatibility groups for different plasmids so... |
by plasmid genes that regulate DNA replication.
if plasmids are closely related they won't both be in the same microbial host. |
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Describe plasmid and transposon nomenclature (don't memorize, just review)
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plasmid nomenclature
pSRQ60: tra+, citronelloli transposon nomenclature TN 1725 (Tc^R) |
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What are 3 ways bacteria move genes? What way has multiple types?
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transformation, transduction, and conjugation
-different types of transduction |
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What are insertion sequences (Is)?
What do they contain? What are they involved with? |
Shorter DNA fragments than transposons.
They only contain genes that are related to insertion. These sequences seem to be involved with gene regulation. |
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Conjugation usually occurs between cells that are...
It involves a BLANK and a BLANK. The donor contains the BLANK BLANK but the recipient does not. |
closely related but different.
a Donor and a Recipient conjugative plasmid |
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Name an example of conjugation involving E.coli. What is the donor and recipient called?
F+ containing cells contain the BLANK and an elongated pilus, the BLANK BLANK. The genes for the pilus are encoded in the BLANK genes. |
Example: With F plasmids (for fertility), the donor is F+ the recipient is F-.
plasmid; sex pilus; tra |
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--Conjugation--
When the cells F+ are mixed with F-, the.. One strand of the F plasmid is nicked at the BLANK, and the BLANK end of the cut strand is transferred to the recipient. The plasmid replicates in the recipient cell via the... The recipient can now act as a donor for... Remember the chromosomes are different. |
the sex pilus aids in the contact between the cells.
oriT site (origin of transfer); 5’ rolling circle model. the F’ plasmid in another mating. |
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Describe High frequency recombination (Hfr) (2 steps)
Why does the F- cell rarely receives the entire F plasmid and therefore remains F-? |
1. First, the F plasmid integrates at several sites in the donor chromosome.
2. When a Hfr cell donates genes into an F- cell, part the F plasmid AND donor chromosome move across into the F- cell. because the mating would have to take 90 minutes. |
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What are F’ plasmids?
If this plasmid is lost via curing, why is this event fatal for the cell? |
These are F plasmids that have integrated into the donor chromosome and are occasionally excised from the chromosome.
Since this plasmid contains part of the chromosome. |
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What is the sex pilus?
When it forms between the donor and recipient cell it is also called... |
Hollow structure consisting of a phosphoprotein called pilin.
the conjugation bridge |
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Mating between Hfr cells and F’ cells allows for the determination of gene location on the chromosome. What is this process called?
Describe the mating process and what it allows for. |
Chromosomal mapping
Mating are conducted at various time intervals and interrupted; this allows for the determination of gene sites. |
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What are transposons? Who discovered them and when?
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Mobile fragments of DNA that can be incorporated into plasmids, bacteriophages and chromosomes discovered in the 1940’s by Barbara McClintock
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At what sites do transposons incorporate?
What do these jumping genes encode for? The ends of their gene sequences contain BLANK BLANK that recognize BLANK BLANK in the DNA for insertion. |
At sites that show complementary base sequences.
These jumping genes encode for antibiotic resistance, toxin production, hydrocarbon utilization, amino acid synthesis. inverted repeats; similar regions |
