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Microbiology
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71
Other
Graduate
05/21/2009

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Term
Monotrichous
Definition
Single Flagelluma at 1 pole
Term
Lophotrichous
Definition
one pole with several flagella
Term
Peritrichous
Definition
flagella all over the cell
Term
Amphitrichous
Definition
flagella at both poles
Term
Endoflagella
Definition
chracteristic of spirochetes, axial filament with flagella in periplasm
Term
Regulon
Definition
multiple operons affected by a single regulatory protein
Term
Stimulon
Definition
multiple genes and operonss whose expression is controlled by a single stimulus. e.g. heat shock proteins
Term
Transitions
Definition
base substitution mutations in which a purine is changed to another purine(A-G) or a pyramidine is switched to another pyramidine (C-T)
Term
Transversions
Definition
base substitution mutations in which a purine is changed to pyramidine(A-T) or a pyramidine is switched to a purine (C-G)
Term
missense mutation
Definition
mutation that results in incorporation of a different amino acid
Term
nonsense mutation
Definition
mutation in which amino acid is changed to a stop codon and prematurely terminates the protein
Term
positive regulation
Definition
binding of the regulatory protein to DNA turns the genes on. in this case the regulator is an activator. the default state is off.
Term
negative regulation
Definition
binding of the regulatory protein to DNA turns the genes off. regulatory protein is called a repressor. default state is on.
Term
inducer
Definition
chemical that binds to a regulatory protein that turns genes on. regulatory protein can be an activator or a repressor. allolactose is an example.
Term
co-repressor
Definition
chemical that binds to a regulatory protein that turns genes off. regulatory protein can be an activator or a repressor.
Term
What has to be present to turn Lac operon on?
Definition
Allolactose must be present to bind and inhibit the repressor from binding to the operator sequence and high levels of cAMP must be present from lack of glucose to bind to CAP. the CAP-cAMP complex then binds to the promoter and interacts with RNA polymerase causing high levels of transcription
Term
What are the 2-3 and 1-4 hairpin in the Trp operon?
Definition
2-3 is the stable interaction of complementary regions that allow further transcription when there is low concentrations of Trp. 1-4 hairpin is formed in Trp excess that will prevent further transcription and serves as the terminator.
Term
What is the phosphorylating type two component system?
Definition
system that enables bacteria to monitor the external environment for signals that differ between the host and the external environment.
Term
quorum sensing
Definition
ability of bacteria to sense cell density
Term
transformation
Definition
transfer of genetic information from one cell to another via naked DNA. sensitive to DNAse, does not require cell to cell contact, does not involve bacteriophage particles.
Term
competence
Definition
ability to bind and take up exogenous naked DNA. DNA is fragmented during uptake. results in transformation
Term
induced transformation
Definition
competence developed under unusual laboratory conditions like high salt and heat shock for E Coli. DNA is taken up in an intact form.
Term
electroporation
Definition
short burst of high electric field that transiently permeabilize the cells and cause them to take up molecules around them. competence is not involved. DNA is taken up in an intact form.
Term
Conjugation
Definition
direct transfer of genetic material from one cell to another via direct cell-cell contact. requires specific surface proteins, DNAse resistant, does not involve a phage
Term
Plasmids
Definition
covalently closed, circular, supercoiled DNA molecules that replicate autonomously, are stably inherited in an extrachromosomal state. can integrate and exist as linear structures too.
Term
Incompatibilty
Definition
prevents two related plasmids from stably replicating in the same cell
Term
Surface exclusion
Definition
property of conjuagative plasmids that prevent entry of a plasmid into a cell that already has a closely related plasmid
Term
host range
Definition
hosts in which the plasmid can replicate
Term
copy number
Definition
number of copies of a plasmid per cell. determined by plasmid replication system and not size.
Term
mobilizable plasmids
Definition
non-conjugative plasmid that can be mobilized to transfer by another conjugative plasmid. they are oriT+ and tra-.
Term
Conjugative plasmids
Definition
have ability to promote their own transfer. are tra+ and oriT+.
Term
Non-mobilizable plasmids
Definition
non-conjugative plasmids that can't transfer under any condition.
Term
F- cells
Definition
have no F factor. are good recipients for DNA tranfer by conjugation.
Term
F+ cells
Definition
contain an extrachromosomal F factor. are poor recipients for conjugation due to their synthesis of surface exclusion proteins
Term
Hfr cells
Definition
the F factor is integrated into the chromosome. are poor recipients for conjugation due to their synthesis of surface exclusion proteins
Term
F' cells
Definition
has an extrachromosomal F factor that also carries some chromosomal genes incorporated during aberrant excision of an integrated plasmid. are poor recipients for conjugation due to their synthesis of surface exclusion proteins
Term
integrons
Definition
discrete DNA elements that carry promotorless antibiotic resistance genes. integrate into specific sites, unlike transposons
Term
transduction
Definition
the transfer of genetic material by a phage particle
Term
generalized transduction
Definition
occurs by mistaken packaging of a piece of host DNA into a phage particle instead of phage DNA
Term
specialized transduction
Definition
occurs by aberrant excision of a prophage leading to incorporation of a small piece of host DNA into the phage genome. found only in lysates made by induction. only genes next to the prophage attachment site are transduced. phage genes are lossed.
Term
abortive transduction
Definition
occurs when transduced DNA does not recombine into host chromosome and instead circularizes to form a plasmid. will be passed down to only one daughter cells and therefore forming microcolonies
Term
High frequency Transducing lysate
Definition
results from a an induced transductant that arises by lysogenation with both a transducing phage and a normal helper phage.
Term
Insertion Sequence
Definition
short 1-2kb DNA segments with a short 15-50 bp inverted repeats at the ends. no detectable phenotypes except transposition.
Term
Direct specimen
Definition
when the pathogen is located in an otherwise sterile site
Term
indirect sample
Definition
whent the pathogen is located in an otherwise sterile site, but must pass through a site containing normal flora
Term
sample from a site with normal flora
Definition
sample collected is a mixture, then the normal flora are inhibited under growth conditions for analysis, e.g. throat swab, stool sample
Term
Agglutination assay
Definition
detection of antibody of patient serum to antigen attached to RBC or latex particle by visible agglutination. Fastest test 5-10 min, but false negative can occur if not sufficient sample size
Term
PCR
Definition
very sensitive analysis that does not require much DNA in specimen. very fast 3-5hrs. It is expensive and prone to having false positives and false negatives.
Term
Real time PCR
Definition
amplification and detection take place at same time. cheaper and faster (1-2 hrs) than regular PCR.
Term
virus
Definition
obligat intracellular parasites that replicate by self-assembly of individual components rather than by binary fission
Term
+ sense RNA
Definition
are same sense as mRNA, they can be used as mRNA.
Term
- sense RNA
Definition
are opposite to mRNA
Term
genome replication for +RNA virus
Definition
translated by host ribosome into polyprotein that is then cleaved. viral RNA dependent RNA polymerase just translated now transcribes a -RNA strand that will be used as a template to generate more +RNA strands that will be translated by host ribosomes
Term
eclipse period
Definition
post penetration phase until a virus can be detected intracellularly. corresponds to uncoating, early transcription, and genome replication steps; ends at virus assembly.
Term
latent period
Definition
post-penetration phase until virus can be detected extracellularly. includes the eclipse period. corresponds to uncoating, early transcription, genome replication, virus assembly, and release.
Term
genome replication pathway in -RNA virus
Definition
incoming viral RNA dependent RNA polymerase transcribes a +RNA strand that is translated by host ribosome into proteins and is used as a template for -RNA genome production.
Term
genome replication in retrovirus
Definition
incoming viral reverse transcriptase converts +RNA viral genome into dsDNA that is integrated into host genome.
Term
Viral Complementation
Definition
wild type virus in cell with mutant virus that can't replicate will be able to infect another cell thanks to helper wild type proteins. however, mutant cell will not be able to replicate after infection. a so called exchange of proteins
Term
Viral Recombination
Definition
an echange of genetic material on the same segment of genome. Mutant cell switches DNA with wild type and now can function normally.
Term
Viral Reassortment
Definition
an exchange of genetic material on different segments of the genome. results in novel strain of virus.
Term
incubation period
Definition
the period postinfection prior to the onset of symptoms
Term
chronic viral infection
Definition
virus is produced at low levels, but may not continue to cause disease symptoms
Term
latent viral infection
Definition
virus genome remains in cells indefinitely, but virus particles are not produce except during reactivation
Term
transforming viral infection
Definition
intact or partial virus genome integrates into cellular DNA or is otherwise maintained in the cell and immortalizes the cell, alters its growth properties
Term
PKR pathway
Definition
protein kinase pathway inactivates translation factor eIF-2, inhibits viral protein translation
Term
2-5a system
Definition
activates RNase L which cleaves RNA, destroying RNA genomes or inhibiting viral transcription
Term
Mx pathway
Definition
proyteins are GTPases that inhibit RNA polymerase activity
Term
disoxaril
Definition
antiviral that fits into cleft in the peceptor binding canyon of the capsid of picornavirus
Term
amantadine/rimantadine
Definition
antiviral that inhibits the uncoating of influenza A by neutralizing the acidity of the the internal viral environment preventing flu virus fusion and escape.
Term
ribavirin
Definition
inhibits nucleoside biosynthesis and as a result inhibits mRNA cap formation and inhibits some RNA polymerases
Term
Relenza/ Tamiflu
Definition
inhibit flu A and B neuraminidase which stops budding
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