60 Questions
Which property of light is the most important in bioanalysis?
Wavelength or photon energy
What are the typical wavelengths used in optical methods in bioanalysis?
200–800 nm
What happens to the light intensity when a molecule absorbs light?
It decreases
What can the detection of light interactions reveal about a sample?
Its properties or surface characteristics
According to the text, which type of semiconductor will have an excess of electrons or negative charge carriers?
N-type semiconductor
According to the text, which type of semiconductor is formed by doping silicon with a trivalent element?
P-type semiconductor
According to the text, what occurs at a p-n junction?
Diffusion
According to the text, which excitation light source produces light by passing electricity through ionized xenon gas at high pressure?
Xenon arc lamp
Which color does Cy3 fluoresce in?
Greenish yellow
Which region of the spectrum does Cy5 fluoresce in?
Red
What is the definition of quantum yield?
The ratio of emitted photons to absorbed photons
What is fluorescence lifetime?
The time required for the molecule to return from the excited state to the ground state
Which wavelengths are commonly used to assess the purity of a DNA solution?
260 nm and 280 nm
What is the ratio A260/A280 for a pure DNA solution?
1.8
What is the extinction coefficient for double stranded DNA?
0.020 L mg–1 cm–1
How does the NanoDrop spectrophotometer work?
It uses the surface tension of aqueous solutions to form a column of sample between two pedestals and directs the light through it
Which of the following is true about a diode?
A diode allows electricity to flow in one direction but not the other
Which of the following is true about biasing a diode?
Forward bias is in the direction of easy current flow
What is a photodiode?
A device that converts light into current
What happens when a photon strikes a photodiode?
The photon is absorbed and converted into light
According to the text, what is photoluminescence?
The emission of light by a substance that has absorbed light or other electromagnetic radiation
What are the two types of photoluminescence?
Fluorescence and phosphorescence
What does the Stokes shift refer to?
The energy difference between the absorbed photon and the emitted photon
Why does the emitted photon usually have less energy than the absorbed photon?
Some of the energy is dissipated as heat and part of the excess energy can be transferred to the surrounding water molecules
Which type of interaction is responsible for the energy transfer in FRET?
Dipole-dipole interactions
What determines the efficiency of the energy transfer in FRET?
The orientation of the dipoles
What is the rate of energy transfer (ket) in FRET given by?
ket = inverse of the fluorescence lifetime of the donor
What does R represent in the Förster equation?
The distance between the donor and acceptor molecules
What is the Förster distance (R0) in FRET?
The distance at which the fluorescence energy transfer is 50% efficient
What does the efficiency of the energy transfer (E) represent in FRET?
The fraction of photon energy absorbed by the donor
Which radioisotope has the longest half-life?
C-14
What is the maximum specific activity of 3H?
28.8 Ci/mmol
What is the main vulnerability of the reproductive organs to radiation?
Sterility
What safety measure should be taken when handling radioisotopes like 32P?
All of the above
Which two modes of detection are commonly used to probe for the presence of certain DNA, RNA, or proteins?
Fluorescence and radioactivity
What is the maximum specific activity of 32P, which is frequently used for detecting DNA and RNA?
9131 Ci/mmol
What is the primary advantage of using 32P in experiments for detecting DNA and RNA?
High emission energy
Which radioactive isotope is commonly used to label proteins and nucleic acids?
35S
Which type of epitopes are common in fibrous proteins?
Continuous
What is the main factor that determines the affinity and interaction between an antibody and an antigen?
Overall three-dimensional structure of the antigen
In competitive immunoassays, what do unlabelled and labelled antigens compete for?
Binding to the antibody
What type of immunoassays are better suited for large analyte molecules?
Non-competitive immunoassays
Which of the following is true about restriction enzymes?
They protect bacteria from invasion by foreign DNA
What is the probability of finding a target of 6 bases?
1/4096
What is the function of DNA ligase?
To seal nicks in the DNA backbone
What is the purpose of Southern blot technique?
To detect specific DNA sequences in DNA samples
According to the text, what is the purpose of Northern Blot?
To determine whether a specific mRNA is present in different cell types
What is the main application of Fluorescence in situ hybridization (FISH)?
To detect and localize specific DNA sequences on chromosomes
What is the purpose of DNA arrays?
To analyze multiple genes simultaneously
What is the purpose of RFLP (Restriction Fragment Length Polymorphism)?
To analyze genetic variations by detecting fragment length differences
Which of the following is true about DNA arrays?
DNA arrays are made up of DNA molecules or oligonucleotides immobilized on a substrate
What is the function of antibodies in the immune system?
To identify and neutralize pathogens
What is the difference between polyclonal and monoclonal antibodies?
Polyclonal antibodies can bind to several different parts (epitopes) on an antigen, while monoclonal antibodies bind to only one particular epitope
What are complete antigens?
Complete antigens can induce an immune response by themselves
Which enzyme is commonly linked to the secondary antibody in Western Blot detection?
Horseradish peroxidase (HRP)
What is the advantage of using chemiluminescent substrates in Western Blot detection?
All of the above
How can the half-life of a protein be determined?
By conducting a pulse-chase experiment
What is the equation to calculate the half-life of a protein in a pulse-chase experiment?
t1/2 = ln2 / γ
What is a biosensor?
A device used for molecular recognition and signal transduction
What is the role of a bioreceptor in a biosensor?
To detect a target analyte
Test your knowledge on cyanines and their applications as fluorescent dyes in biomedical imaging. Learn about the different structures and spectrums they cover, with a focus on the popular Cy3 and Cy5 variants. Explore the terminology and quantum properties associated with these compounds.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
