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11 votes
Accepted

Why is there a λ⁴ in the spectral overlap integral in FRET calculations

Why this is such a good question After finishing teaching at 8pm EDT, it took me about 1 hour to find the answer and 1.5 hours writing this answer and confirming things. The Wikipedia article just ...
user1271772's user avatar
6 votes

If you measure the O.D. of cells at one wavelength, is it possible to find its equivalent O.D. at another wavelength?

O.D. can mean 30 different things, many of them being related to science and to optics (see here)! I'll assume you mean absorbance (for Optical Density I'd guess) or light scattering as @canadianer ...
Remi.b's user avatar
  • 68.1k
4 votes

If you measure the O.D. of cells at one wavelength, is it possible to find its equivalent O.D. at another wavelength?

As already said by Remi.b, there is no way you can directly convert the O.D.550 to an O.D.600. However, in case you already made numerous experiments using O.D.550, you may not have to do them all ...
Flo's user avatar
  • 707
4 votes

Spectroscopic methods for quantifying peptides/proteins with or without Tryptophan or Tyrosine content

I think it would not be a problem if you use NanoDrop for your measurements. But there are better options if using UV-Vis is not a strict rule. Alternatively, Qubit itself doesn't have any issues ...
cc12amu's user avatar
  • 126
4 votes

Why does absorption (at 260nm) of ssDNA increase with temperature?

It seems canadianer's intuition is correct -- Base stacking still occurs in ssDNA, so I suspect that is why you see a temperature dependence -- based on this paper: Conformational Changes in Single-...
acvill's user avatar
  • 8,296
4 votes
Accepted

Using nanodrop for analysing biological samples other than nucleotides

The Nanodrop is a generic UV-visible spectrophotometer. According to the manufacturer, the latest model can measure absorbance from 190 to 850 nm. Its dynamic range is also very good: from about 0.1 ...
Guillaume's user avatar
  • 715
3 votes

Why do most plants reflect green and others other colors?

All photosynthetic plants contain chlorophyll, and chlorophyll is green (leaving out various algae). Plant leaves often contain other pigments, which can mask the chlorophyll's green, or be masked by ...
jamesqf's user avatar
  • 3,643
3 votes

What happens to the absorbed blue and red light in the chlorophyll molecule?

It is glad to say that we can enter to this question due to having of valuable theorem of 1st law of thermodynamics. Energy cannot be destroy but it can convert in to another type of energy.The ...
Osal Thuduwage's user avatar
2 votes
Accepted

How do carbon 13:12 ratios confirm the biological origin of oldest microfossils?

Via: https://en.wikipedia.org/wiki/Carbon-13#Uses_in_science Due to differential uptake in plants as well as marine carbonates of 13C, it is possible to use these isotopic signatures in earth ...
Alex Reynolds's user avatar
2 votes
Accepted

How do we see the violet color?

Color perception: There are several competing/complementary theories of color perception: the most popular, trichromatic theory, being complemented by the opponent process theory. There is also Land’s ...
Rich's user avatar
  • 326
2 votes

Identifying substance in body fluid (serum, urine)

Dipstick urinalysis? source The urine dipstick has a bunch of squares, each with a chemical analysis ready to go. The dip will semiquantitatively show you what is in the urine. My bet would be ...
Willk's user avatar
  • 2,964
1 vote

CD spectra of Porin molecules?

CD (circular dichroism) spectrum of porin will look like CD spectra of most beta-sheet-reach proteins. You can look, for example, paper on PorB protein (Minetti et al, JBC, 1998) where authors present ...
Volodymyr's user avatar
  • 119
1 vote

What does the spectrum of Chlorophyll fluorescence look like?

I think for your purpose you should start, for example, with this link: https://academic.oup.com/jxb/article/60/11/2987/533160 UPD: Chlorophyllous tissues emit radiation of wavelengths approximately ...
Daria Sukhova's user avatar
1 vote

Using nanodrop for analysing biological samples other than nucleotides

I used the Nanodrop for the measurement of the absorbance at 600 nm of bacterial cultures, as well as nucleic acid preparations. However, I switched to using another spectrophotometer (...
charlesdarwin's user avatar
1 vote

How can I calculate alpha helix content from molar ellipticity?

You can use the information at this site, especially section 3. (https://www.photophysics.com/resources/tutorials/circular-dichroism-cd-spectroscopy) Notice the different CD spectra for alpha-helix, ...
Jeppe Nielsen's user avatar

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