BIO219 Final Exam Questions With
Complete Solutions
Describe the Lux operon The Lux operon is a region of DNA that encodes for proteins
necessary for bioluminescence. It is 8.5 kb in size arranged in the order LuxRICDABE.
Lux operon components & their functions. LuxI- encodes for the auto-inducer synthase
(N-acyl homoserine lactone / AHL)
LuxR- encodes for the transcriptional activator that binds the auto inducer
LuxCDE- fatty acid reductase complex components:
LuxC- Acyl-reductase enzyme
LuxD- Acyl-transferase enzyme
LuxE- Acyl-protein synthetase enzyme
LuxAB- alpha and beta subunits of luciferase, the catalyst for the bioluminescent reaction
Fatty acid reductase complex function Allows to break down the acyl chains and emit
light - the whole point of the lux operon
Biochemical reaction of bioluminescence formula & description FMNH2 + RCHO + 02 -
> FMN + H2O + RCOOH
, BIO219 Final Exam Questions With
Complete Solutions
simple description: ** more in depth for exam luciferase catalyzes oxidation of luciferin
What is quorum sensing Quorum sensing is a population density based method of
molecular signalling and gene regulation. This allows for cells to communicate via autoinducers.
In A. fischeri, AHL serves as the autoinducer, and in high quantities this allows for
bioluminescence. Bioluminescence will not occur with a low density of cells, because not
enough autoinducers will be produced. Quorum sensing also allows for other processes such as
biofilm formation, which occurs when bacteria have a high cell density and produce
autoinducers, which signal to each other and upregulate the formation of the necessary proteins
for the biofilm.
What is autoinduction? Autoinduction happens through autocrine signalling, where a cell
sends out a small signal molecule (autoinducer), such as AHL. The molecule then comes back
into the same cell it was released from and turns on an operon. This function does not allow for
bioluminescence in an individual cell, but allows for production to be ramped up and allows for
quorum sensing to occur.
LuxR homolog in E. coli SdiA
, BIO219 Final Exam Questions With
Complete Solutions
Can E. coli use quorum sensing, if so, how? Yes, E. coli uses quorum sensing by picking
up small molecules from other organisms in the environment. ** add to this answer
What is the GadAX operon? The GADAX operon contains the GadA gene, which can be
upregulated by AHL. This is the target of this experiment. The operon as a whole is responsible
for the glutamate-dependent acid resistance system in E. coli, which allows it to exist under
acidic conditions.
SdiA, a homolog of the LuxR gene. SdiA produces an autoinducer receptor, so when the LuxI
gene is transformed to SdiA, AHL is able to be received by it. NOT IN GADAX operon
WEEK ONE - chDNA isolation week one is after this card
Structure of bacterial chromosomes circular, double stranded, often supercoiled
Reagents needed for the lysis phase of chDNA & their function 1. Resuspension buffer -
disrupts the lipid bilayer and re-suspends the cells so they are all planktonic with no clumping
Complete Solutions
Describe the Lux operon The Lux operon is a region of DNA that encodes for proteins
necessary for bioluminescence. It is 8.5 kb in size arranged in the order LuxRICDABE.
Lux operon components & their functions. LuxI- encodes for the auto-inducer synthase
(N-acyl homoserine lactone / AHL)
LuxR- encodes for the transcriptional activator that binds the auto inducer
LuxCDE- fatty acid reductase complex components:
LuxC- Acyl-reductase enzyme
LuxD- Acyl-transferase enzyme
LuxE- Acyl-protein synthetase enzyme
LuxAB- alpha and beta subunits of luciferase, the catalyst for the bioluminescent reaction
Fatty acid reductase complex function Allows to break down the acyl chains and emit
light - the whole point of the lux operon
Biochemical reaction of bioluminescence formula & description FMNH2 + RCHO + 02 -
> FMN + H2O + RCOOH
, BIO219 Final Exam Questions With
Complete Solutions
simple description: ** more in depth for exam luciferase catalyzes oxidation of luciferin
What is quorum sensing Quorum sensing is a population density based method of
molecular signalling and gene regulation. This allows for cells to communicate via autoinducers.
In A. fischeri, AHL serves as the autoinducer, and in high quantities this allows for
bioluminescence. Bioluminescence will not occur with a low density of cells, because not
enough autoinducers will be produced. Quorum sensing also allows for other processes such as
biofilm formation, which occurs when bacteria have a high cell density and produce
autoinducers, which signal to each other and upregulate the formation of the necessary proteins
for the biofilm.
What is autoinduction? Autoinduction happens through autocrine signalling, where a cell
sends out a small signal molecule (autoinducer), such as AHL. The molecule then comes back
into the same cell it was released from and turns on an operon. This function does not allow for
bioluminescence in an individual cell, but allows for production to be ramped up and allows for
quorum sensing to occur.
LuxR homolog in E. coli SdiA
, BIO219 Final Exam Questions With
Complete Solutions
Can E. coli use quorum sensing, if so, how? Yes, E. coli uses quorum sensing by picking
up small molecules from other organisms in the environment. ** add to this answer
What is the GadAX operon? The GADAX operon contains the GadA gene, which can be
upregulated by AHL. This is the target of this experiment. The operon as a whole is responsible
for the glutamate-dependent acid resistance system in E. coli, which allows it to exist under
acidic conditions.
SdiA, a homolog of the LuxR gene. SdiA produces an autoinducer receptor, so when the LuxI
gene is transformed to SdiA, AHL is able to be received by it. NOT IN GADAX operon
WEEK ONE - chDNA isolation week one is after this card
Structure of bacterial chromosomes circular, double stranded, often supercoiled
Reagents needed for the lysis phase of chDNA & their function 1. Resuspension buffer -
disrupts the lipid bilayer and re-suspends the cells so they are all planktonic with no clumping
