Cyanine Fluorescent Dyes in Biomedical Imaging
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Questions and Answers

Which property of light is the most important in bioanalysis?

  • Wavelength or photon energy (correct)
  • Speed of light
  • Intensity of transmitted light
  • Wave-particle duality

    • What are the typical wavelengths used in optical methods in bioanalysis?

  • 500–1000 nm
  • 200–800 nm (correct)
  • 100–500 nm
  • 800–2000 nm

    • What happens to the light intensity when a molecule absorbs light?

  • It decreases (correct)
  • It increases
  • It fluctuates
  • It remains the same

    • What can the detection of light interactions reveal about a sample?

    <p>Its properties or surface characteristics</p> Signup and view all the answers

    According to the text, which type of semiconductor will have an excess of electrons or negative charge carriers?

    <p>N-type semiconductor</p> Signup and view all the answers

    According to the text, which type of semiconductor is formed by doping silicon with a trivalent element?

    <p>P-type semiconductor</p> Signup and view all the answers

    According to the text, what occurs at a p-n junction?

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

    According to the text, which excitation light source produces light by passing electricity through ionized xenon gas at high pressure?

    <p>Xenon arc lamp</p> Signup and view all the answers

    Which color does Cy3 fluoresce in?

    <p>Greenish yellow</p> Signup and view all the answers

    Which region of the spectrum does Cy5 fluoresce in?

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

    What is the definition of quantum yield?

    <p>The ratio of emitted photons to absorbed photons</p> Signup and view all the answers

    What is fluorescence lifetime?

    <p>The time required for the molecule to return from the excited state to the ground state</p> Signup and view all the answers

    Which wavelengths are commonly used to assess the purity of a DNA solution?

    <p>260 nm and 280 nm</p> Signup and view all the answers

    What is the ratio A260/A280 for a pure DNA solution?

    <p>1.8</p> Signup and view all the answers

    What is the extinction coefficient for double stranded DNA?

    <p>0.020 L mg–1 cm–1</p> Signup and view all the answers

    How does the NanoDrop spectrophotometer work?

    <p>It uses the surface tension of aqueous solutions to form a column of sample between two pedestals and directs the light through it</p> Signup and view all the answers

    Which of the following is true about a diode?

    <p>A diode allows electricity to flow in one direction but not the other</p> Signup and view all the answers

    Which of the following is true about biasing a diode?

    <p>Forward bias is in the direction of easy current flow</p> Signup and view all the answers

    What is a photodiode?

    <p>A device that converts light into current</p> Signup and view all the answers

    What happens when a photon strikes a photodiode?

    <p>The photon is absorbed and converted into light</p> Signup and view all the answers

    According to the text, what is photoluminescence?

    <p>The emission of light by a substance that has absorbed light or other electromagnetic radiation</p> Signup and view all the answers

    What are the two types of photoluminescence?

    <p>Fluorescence and phosphorescence</p> Signup and view all the answers

    What does the Stokes shift refer to?

    <p>The energy difference between the absorbed photon and the emitted photon</p> Signup and view all the answers

    Why does the emitted photon usually have less energy than the absorbed photon?

    <p>Some of the energy is dissipated as heat and part of the excess energy can be transferred to the surrounding water molecules</p> Signup and view all the answers

    Which type of interaction is responsible for the energy transfer in FRET?

    <p>Dipole-dipole interactions</p> Signup and view all the answers

    What determines the efficiency of the energy transfer in FRET?

    <p>The orientation of the dipoles</p> Signup and view all the answers

    What is the rate of energy transfer (ket) in FRET given by?

    <p>ket = inverse of the fluorescence lifetime of the donor</p> Signup and view all the answers

    What does R represent in the Förster equation?

    <p>The distance between the donor and acceptor molecules</p> Signup and view all the answers

    What is the Förster distance (R0) in FRET?

    <p>The distance at which the fluorescence energy transfer is 50% efficient</p> Signup and view all the answers

    What does the efficiency of the energy transfer (E) represent in FRET?

    <p>The fraction of photon energy absorbed by the donor</p> Signup and view all the answers

    Which radioisotope has the longest half-life?

    <p>C-14</p> Signup and view all the answers

    What is the maximum specific activity of 3H?

    <p>28.8 Ci/mmol</p> Signup and view all the answers

    What is the main vulnerability of the reproductive organs to radiation?

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

    What safety measure should be taken when handling radioisotopes like 32P?

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

    Which two modes of detection are commonly used to probe for the presence of certain DNA, RNA, or proteins?

    <p>Fluorescence and radioactivity</p> Signup and view all the answers

    What is the maximum specific activity of 32P, which is frequently used for detecting DNA and RNA?

    <p>9131 Ci/mmol</p> Signup and view all the answers

    What is the primary advantage of using 32P in experiments for detecting DNA and RNA?

    <p>High emission energy</p> Signup and view all the answers

    Which radioactive isotope is commonly used to label proteins and nucleic acids?

    <p>35S</p> Signup and view all the answers

    Which type of epitopes are common in fibrous proteins?

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

    What is the main factor that determines the affinity and interaction between an antibody and an antigen?

    <p>Overall three-dimensional structure of the antigen</p> Signup and view all the answers

    In competitive immunoassays, what do unlabelled and labelled antigens compete for?

    <p>Binding to the antibody</p> Signup and view all the answers

    What type of immunoassays are better suited for large analyte molecules?

    <p>Non-competitive immunoassays</p> Signup and view all the answers

    Which of the following is true about restriction enzymes?

    <p>They protect bacteria from invasion by foreign DNA</p> Signup and view all the answers

    What is the probability of finding a target of 6 bases?

    <p>1/4096</p> Signup and view all the answers

    What is the function of DNA ligase?

    <p>To seal nicks in the DNA backbone</p> Signup and view all the answers

    What is the purpose of Southern blot technique?

    <p>To detect specific DNA sequences in DNA samples</p> Signup and view all the answers

    According to the text, what is the purpose of Northern Blot?

    <p>To determine whether a specific mRNA is present in different cell types</p> Signup and view all the answers

    What is the main application of Fluorescence in situ hybridization (FISH)?

    <p>To detect and localize specific DNA sequences on chromosomes</p> Signup and view all the answers

    What is the purpose of DNA arrays?

    <p>To analyze multiple genes simultaneously</p> Signup and view all the answers

    What is the purpose of RFLP (Restriction Fragment Length Polymorphism)?

    <p>To analyze genetic variations by detecting fragment length differences</p> Signup and view all the answers

    Which of the following is true about DNA arrays?

    <p>DNA arrays are made up of DNA molecules or oligonucleotides immobilized on a substrate</p> Signup and view all the answers

    What is the function of antibodies in the immune system?

    <p>To identify and neutralize pathogens</p> Signup and view all the answers

    What is the difference between polyclonal and monoclonal antibodies?

    <p>Polyclonal antibodies can bind to several different parts (epitopes) on an antigen, while monoclonal antibodies bind to only one particular epitope</p> Signup and view all the answers

    What are complete antigens?

    <p>Complete antigens can induce an immune response by themselves</p> Signup and view all the answers

    Which enzyme is commonly linked to the secondary antibody in Western Blot detection?

    <p>Horseradish peroxidase (HRP)</p> Signup and view all the answers

    What is the advantage of using chemiluminescent substrates in Western Blot detection?

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

    How can the half-life of a protein be determined?

    <p>By conducting a pulse-chase experiment</p> Signup and view all the answers

    What is the equation to calculate the half-life of a protein in a pulse-chase experiment?

    <p>t1/2 = ln2 / γ</p> Signup and view all the answers

    What is a biosensor?

    <p>A device used for molecular recognition and signal transduction</p> Signup and view all the answers

    What is the role of a bioreceptor in a biosensor?

    <p>To detect a target analyte</p> Signup and view all the answers

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