UV/Visible Spectroscopy Basics Quiz
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Questions and Answers

What is the primary purpose of fluorescence spectroscopy?

  • To separate molecules based on charge in an electric field
  • To measure the size of molecules based on their fluorescence
  • To excite electrons in a sample with light and measure lower energy light emission (correct)
  • To denature proteins and run them in a gel

    • Which characteristic is associated with fluorescent molecules?

  • Highly conjugated systems, many rings, and rigid and planar structure (correct)
  • Small size and random orientation
  • Large molecular weight and irregular shape
  • Low energy levels and flexible structure

    • What is the Stoke shift in fluorescence spectroscopy?

  • The interference caused by the light source and prism
  • The difference between excitation and emission wavelengths (correct)
  • The measure of energy transfer in the sample
  • The sensitivity of the fluorescence spectrophotometer

    • How do fluorescence spectrophotometers avoid interference?

    <p>By measuring emission at right angles to the light source</p> Signup and view all the answers

    What does size exclusion chromatography use to separate molecules?

    <p>A column and a mobile and stationary phase</p> Signup and view all the answers

    How does size exclusion chromatography separate molecules?

    <p>Based on size, with small molecules entering beads and large ones excluded</p> Signup and view all the answers

    What is the primary principle behind dialysis?

    <p>Separating molecules based on size using a semi-permeable membrane</p> Signup and view all the answers

    How does electrophoresis separate molecules?

    <p>Based on charge in an electric field, with agarose gels acting as a molecular sieve</p> Signup and view all the answers

    What is the main purpose of UV/visible Spectroscopy?

    <p>All of the above</p> Signup and view all the answers

    What happens when a compound absorbs UV energy?

    <p>Electrons are promoted to higher energy levels</p> Signup and view all the answers

    How is transmittance calculated in UV spectroscopy?

    <p>As the percentage of light that passes through the substance</p> Signup and view all the answers

    What does high absorbance indicate in UV spectroscopy?

    <p>A high concentration of absorbing molecules</p> Signup and view all the answers

    Which law states that light absorption is proportional to the path length?

    <p>Lambert's law</p> Signup and view all the answers

    At which wavelength does DNA absorb UV light?

    <p>$260nm$</p> Signup and view all the answers

    Which amino acid side chains absorb UV light around $280/274nm$?

    <p>$Tryptophan and tyrosine$</p> Signup and view all the answers

    Which prosthetic group absorbs UV light at $400nm$?

    <p>$Haem$</p> Signup and view all the answers

    Fluorescence spectroscopy uses light to excite electrons, causing them to emit higher energy light.

    <p>False</p> Signup and view all the answers

    Stoke shift is the term for the difference between excitation and emission wavelengths in fluorescence spectroscopy.

    <p>True</p> Signup and view all the answers

    Fluorescence spectrophotometers measure emission at right angles to avoid interference.

    <p>True</p> Signup and view all the answers

    Dialysis separates molecules based on charge in an electric field.

    <p>False</p> Signup and view all the answers

    Agarose gels are used in size exclusion chromatography to separate molecules based on size.

    <p>False</p> Signup and view all the answers

    Proteins can be separated using electrophoresis, with DNA running in a thinner gel.

    <p>False</p> Signup and view all the answers

    SDS-PAGE separates proteins by denaturing them and running them in a thicker gel.

    <p>False</p> Signup and view all the answers

    Size exclusion chromatography separates molecules based on their charge.

    <p>False</p> Signup and view all the answers

    UV energy is similar to the bonding in organic molecules.

    <p>True</p> Signup and view all the answers

    Absorbance is calculated as log10(I0/I)

    <p>True</p> Signup and view all the answers

    Beer's law states that light absorption is proportional to the number of absorbing molecules (concentration)

    <p>True</p> Signup and view all the answers

    Lambert's law states that light absorption is proportional to path length (width of sample the light is passed through)

    <p>True</p> Signup and view all the answers

    DNA absorbs UV light at 260nm.

    <p>True</p> Signup and view all the answers

    Peptide bond in proteins absorbs UV light at 190nm.

    <p>True</p> Signup and view all the answers

    Tryptophan and tyrosine amino acid side chains absorb around 280/274nm.

    <p>True</p> Signup and view all the answers

    Study Notes

    • Fluorescence spectroscopy involves exciting electrons in a sample with light, causing them to emit lower energy light

    • GFP, a naturally fluorescent protein, is widely used in biotechnology

    • Fluorescent molecules have highly conjugated systems, many rings, and are rigid and planar

    • Stoke shift is the difference between excitation and emission wavelengths, with larger shifts increasing sensitivity

    • Fluorescence spectrophotometers use a light source, prism, slits, and measure emission at right angles to avoid interference

    • Fluorescence offers enhanced sensitivity and specificity, but can be affected by energy transfer and not all compounds are fluorescent

    • Molecules can be separated using techniques like size exclusion chromatography, which uses a column and a mobile and stationary phase

    • Size exclusion chromatography separates molecules based on size, with small molecules entering beads and large ones excluded

    • Dialysis uses a semi-permeable membrane to separate molecules based on size, with small molecules passing through and large ones remaining in solution

    • Electrophoresis separates molecules based on charge in an electric field, with agarose gels acting as a molecular sieve

    • DNA and proteins can be separated using electrophoresis, with DNA negatively charged and separated using agarose gels in a tank.

    • Proteins can be separated using SDS-PAGE, which denatures them and runs them in a thinner gel.

    • Fluorescence spectroscopy involves exciting electrons in a sample with light, causing them to emit lower energy light

    • GFP, a naturally fluorescent protein, is widely used in biotechnology

    • Fluorescent molecules have highly conjugated systems, many rings, and are rigid and planar

    • Stoke shift is the difference between excitation and emission wavelengths, with larger shifts increasing sensitivity

    • Fluorescence spectrophotometers use a light source, prism, slits, and measure emission at right angles to avoid interference

    • Fluorescence offers enhanced sensitivity and specificity, but can be affected by energy transfer and not all compounds are fluorescent

    • Molecules can be separated using techniques like size exclusion chromatography, which uses a column and a mobile and stationary phase

    • Size exclusion chromatography separates molecules based on size, with small molecules entering beads and large ones excluded

    • Dialysis uses a semi-permeable membrane to separate molecules based on size, with small molecules passing through and large ones remaining in solution

    • Electrophoresis separates molecules based on charge in an electric field, with agarose gels acting as a molecular sieve

    • DNA and proteins can be separated using electrophoresis, with DNA negatively charged and separated using agarose gels in a tank.

    • Proteins can be separated using SDS-PAGE, which denatures them and runs them in a thinner gel.

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    Description

    Test your knowledge of UV/visible spectroscopy with this quiz. Learn about the principles and applications of spectroscopy, including compound identification, molecular structure determination, and substance quantification.

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