CO2 functions both as an activator and as a substrate in the reaction catalyzed by rubisco.

#Id: 2561

#Unit 13. Methods in Biology

An excited fluorescent molecule such as GFP or YFP can dispose of the energy from the absorbed photon in either of two ways: 

by fluorescence, emitting a photon of slightly longer wavelength (lower energy) than the exciting light, or 

by nonradiative fluorescence resonance energy transfer (FRET).

#Id: 2562

#Unit 13. Methods in Biology

FRET is inversely proportional to the sixth power of the distance between donor and acceptor. 

#Id: 2563

#Unit 13. Methods in Biology

Molecular beacons are FRET-labelled single-stranded hairpin-shaped oligonucleotide probes originally developed by Tyagi and Kramer in 1996.

#Id: 2564

#Unit 13. Methods in Biology

The loop region of the beacon is designed to bind specifically to a target nucleic acid. Thus, in the presence of the target nucleic acid, the stem region of the beacon becomes separated, releasing the fluorophore from the quencher such that active fluorescence can be observed.

#Id: 2565

#Unit 13. Methods in Biology

Molecular beacons consist of a stem (5–7 bp), and a loop (18–30 base pairs) and are labeled at the 5′ and 3′ ends by fluorophores and quenchers, respectively. 

#Id: 4707

#Unit 13. Methods in Biology

From the four possible transitions (n!p*, p!p*, n!s*, s!s*), only two can be elicited with light from the UV/Vis spectrum for some biological molecules: n!p* and p!p*. The n!s* and s!s* transitions are

energetically not within the range of UV/Vis spectroscopy and require higher energies.