Bioluminescence

Question 1

What is bioluminescence?

Answer 1

Light production by living organisms via enzymatic oxidation of luciferin.

Question 2

What are the components of bioluminescence?

Answer 2

Luciferin, luciferase, oxygen, and sometimes cofactors like ATP or Ca²⁺.

Question 3

Define luciferin.

Answer 3

The light-emitting substrate in bioluminescence.

Question 4

Define luciferase.

Answer 4

The enzyme that oxidizes luciferin, producing light.

Question 5

What type of chemical reaction produces bioluminescence?

Answer 5

Oxidation reaction that emits photons.

Question 6

What is a photoprotein?

Answer 6

A protein (like aequorin) that emits light when bound to calcium.

Question 7

What is aequorin?

Answer 7

A calcium-sensitive photoprotein from jellyfish Aequorea victoria.

Question 8

What happens when calcium binds to aequorin?

Answer 8

It triggers a conformational change that emits blue light.

Question 9

What is the role of GFP in jellyfish?

Answer 9

It absorbs blue light and emits green light via energy transfer.

Question 10

How does BRET/FRET work?

Answer 10

Transfers energy between closely spaced fluorophores to study protein interactions.

Question 11

What is counterillumination?

Answer 11

Bioluminescence that matches background light to camouflage organisms.

Question 12

What is quorum sensing?

Answer 12

Bacteria detect cell density via autoinducers to coordinate behaviors like light production.

Question 13

What is the lux operon?

Answer 13

A gene cluster in bacteria coding for bioluminescent machinery.

Question 14

What do luxA and luxB code for?

Answer 14

The alpha and beta subunits of bacterial luciferase.

Question 15

What triggers lux operon activation?

Answer 15

High concentrations of autoinducer molecules from dense bacterial populations.

Question 16

What organism hosts Vibrio fischeri?

Answer 16

The Hawaiian bobtail squid (Euprymna scolopes).

Question 17

What is the purpose of bioluminescence in the bobtail squid?

Answer 17

Camouflage via counterillumination to avoid predators.

Question 18

How does the squid control light emission?

Answer 18

Using pigmented lids or rotating organs to block or direct light.

Question 19

How do flashlight fish use bioluminescence?

Answer 19

To hunt at night and confuse predators by blinking and redirecting movement.

Question 20

Why emit red/orange light in the deep sea?

Answer 20

Red light is invisible to most organisms; helps with stealth predation.

Question 21

What is fluorescence?

Answer 21

Emission of light after absorbing external light (requires excitation).

Question 22

How is phosphorescence different from fluorescence?

Answer 22

It is delayed emission after light exposure (longer-lasting glow).

Question 23

What is the main difference between fluorescence and bioluminescence?

Answer 23

Fluorescence needs light to excite it; bioluminescence produces light chemically.

Question 24

How is aequorin used in science?

Answer 24

As a calcium sensor in cells for imaging intracellular Ca²⁺ levels.

Question 25

How is BRET used for protein interaction studies?

Answer 25

By detecting energy transfer between fused photoproteins when proteins bind. Fuse protein A to luciferase (donor), protein B to fluorescent protein (acceptor). Co-express both in living cells. Add substrate (e.g., coelenterazine) → luciferase emits light. If A and B interact, donor and acceptor are close enough for energy transfer. Measure the BRET ratio (acceptor vs donor emission) to detect interaction.

Question 26

What is a luciferase reporter gene?

Answer 26

A gene used to track promoter activity by measuring emitted light.

Question 27

How is luciferase used in drug screening?

Answer 27

It signals gene expression changes in response to drug treatments. A luciferase gene is placed under the control of a promoter that responds to a pathway of interest (e.g., estrogen receptor). Add drug → if it activates/inhibits that pathway → luciferase is expressed → light is produced. More light = more activation (or the opposite, depending on setup).

Question 28

How are bioluminescent bacteria used in pollution monitoring?

Answer 28

Light production stops in the presence of toxins → acts as a biosensor.

Question 29

Why is bioluminescence ideal for low-background detection?

Answer 29

Because it emits light only when the reaction occurs (no background fluorescence).

Question 30

What challenges exist in engineering bioluminescent systems?

Answer 30

Multi-protein complexity, need for specific substrates, and host compatibility.