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BIO 219 FINAL EXAM – Accurately Answered Questions
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BIO 219 FINAL EXAM – Accurately Answered Questions
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BIO 219 FINAL EXAM – Accurately Answered QuestionsWhat are the two purposes to the quarter-long project Right Ans - to
isolate the lix operon from Aliivibrio fischeri genomic DNA and transform
E.coli to induce bioluminesce
To quantify gene expression changes in E.coli after transformation using the
gadA system
What bioluminescent bacterial organism did we use? Right Ans - A. fischeri
Gram negative rod shaped bacteria
Found in marine environments
It’s chromosomal dna contains the lux operon needed for bioluminescence
Explain the symbiotic relationship between a.fischeri and the creatures that
house it Right Ans - 96% of all deep sea creatures have this relationship
Hosts benefit through communication, attracting prey, hiding from predators,
and attracting a mate
Bacteria benefit through reliable food sources and protection
Two organisms that have a symbiotic relationship with a.fischeri Right Ans
- lophius piscatorius (angler fish)
euprymna scolopes (hawaiian bobtail fish)
What is the lux operon? Right Ans - causes bioluminescence (transcription
of chemical components)
emits blue-green light at 490nm
Lux operon structure Right Ans - luxi
luxr
,luxc
luxd
luxa
luxb
luxe
LuxI Right Ans - encodes for the Auto-inducer
LuxR Right Ans - encodes for the transcriptional activator that binds the
auto inducer
luxC Right Ans - encodes for the Acyl-reductase enzyme
luxD Right Ans - encodes for the acyl-transferase enzyme
luxA Right Ans - encodes for the alpha subunit of luciferase - has the active
site for enzyme
luxB Right Ans - encodes for the beta subunit of luciferase - absolutely
necessary for the activity of enzyme
luxE Right Ans - encodes for acyl-protein synthetase enzyme
Bioluminescence reaction Right Ans - oxidation of luciferin catalyzed by
luciferase
FMNH2 + O2 + R-CHO -> FMN + R-COOH + H2O + Light
Oxygen oxidizes flavin mononucleotide and a long aliphatic aldehyde to a
aliphatic craboxylic acid
hydroxyflavin intermediate product which is dehydrated to FMN to produce
light
Genes transcribed as Right Ans - polycistronic mRNA
, Auto-inducer + luxR gene product bind where? Right Ans - between luxr
and luxi to start gene expression of lux operon
What is quorum sensing? Right Ans - the regulation of gene expression in
response to fluctuations in cell-population density
Auto-induction Right Ans - a metabolic process in which a drug stimulates
the production of enzymes that enhance its own metabolism, which leads to a
reduction in drug concentrations
AHL Right Ans - N-acyl homoserine lactone
Freely diffused across the cell membrane into the extra cellular membrane
As the density of bacteria increases, more of the induced is released into the
extra cellular membrane
E. coli Right Ans - gram negative, rod shaped
Lacks lux operon but can still respond to AHL
What is the E.Coli LuxR homolog? Right Ans - encodes SdiA to detect AHL
luxi does not have a homolog, cannot produce AHL on its own
SdiA Right Ans - detect the presence of AHLs and induce up-regulation of
the gadAX operon (which contains gadA gene)
can e.coli use quorum sensing? if so how does e.coli do this in nature? Right
Ans - can quorum sense other organisms that produce AHL, to up or down
regulate
gadA is upregulated in presence on an auto inducer
gadA Right Ans - encodes for a glutamate decarboxylase that plays a role in
acid tolerance
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