UV/VIS and CD Spectroscopy UPDATED
ACTUAL Questions and CORRECT
Answers
What is CD Spectroscopy? - CORRECT ANSWER -A technique that measures the difference in
absorption of the left and right circularly polarized light. This helps to determine the secondary structures
of chiral molecules, such as proteins, since the signal between LCPL and RCPL are different at each
wavelength. Alpha helices and Beta sheets have unique CD peaks/signals.
What does CD actually measure? - CORRECT ANSWER -The difference between the absorbed
left and right circularly polarized light. Circularly polarized light will rotate in a spiral pattern that moves
forward with these two types. Chiral molecules and secondary structures will interact with polarized light
differently.
Why do we measure the absorbance of molecules? How do we do this? - CORRECT ANSWER -To
understand the absorption and concentrations of your molecule depending on the wavelength,
pathlenghth, and molar absorptivity. The Beer-Lambert law and the absorbance log help show this. A =
log (I in / I) where this the light in over the light out, since the biomolecule should absorb some
photons/light.
Explain the Beer-Lambert law. - CORRECT ANSWER -A = ebc, where:
A = absorbance
e = molar absorptivity (M-1cm-1)
b = path length or distance the light has to travel (cm)
c = concentration of biomolecule (M)
What does Molar Absorptivity help with? - CORRECT ANSWER -This is a physical property of
your molecule. It is a measure of how much light the molecule will absorb at a specific wavelength,
where this varies with wavelength. Note: all molecules absorb light because of electrons; the difference is
which wavelengths they absorb and how much light they can absorb (e)
ACTUAL Questions and CORRECT
Answers
What is CD Spectroscopy? - CORRECT ANSWER -A technique that measures the difference in
absorption of the left and right circularly polarized light. This helps to determine the secondary structures
of chiral molecules, such as proteins, since the signal between LCPL and RCPL are different at each
wavelength. Alpha helices and Beta sheets have unique CD peaks/signals.
What does CD actually measure? - CORRECT ANSWER -The difference between the absorbed
left and right circularly polarized light. Circularly polarized light will rotate in a spiral pattern that moves
forward with these two types. Chiral molecules and secondary structures will interact with polarized light
differently.
Why do we measure the absorbance of molecules? How do we do this? - CORRECT ANSWER -To
understand the absorption and concentrations of your molecule depending on the wavelength,
pathlenghth, and molar absorptivity. The Beer-Lambert law and the absorbance log help show this. A =
log (I in / I) where this the light in over the light out, since the biomolecule should absorb some
photons/light.
Explain the Beer-Lambert law. - CORRECT ANSWER -A = ebc, where:
A = absorbance
e = molar absorptivity (M-1cm-1)
b = path length or distance the light has to travel (cm)
c = concentration of biomolecule (M)
What does Molar Absorptivity help with? - CORRECT ANSWER -This is a physical property of
your molecule. It is a measure of how much light the molecule will absorb at a specific wavelength,
where this varies with wavelength. Note: all molecules absorb light because of electrons; the difference is
which wavelengths they absorb and how much light they can absorb (e)
