Protein Engineering Multiple Choice Questions on “Structural Study – Mass Spectroscopy – 1”.
1. Which of the following technique is used to determine the protein sequence?
A. X – ray crystallography
B. NMR spectroscopy
C. Atomic spectroscopy
D. Mass spectroscopy
Answer: D
Clarification: Mass spectroscopy is a technique that is used to determine the protein sequence. X – ray crystallography, NMR spectroscopy, and atomic spectroscopy cannot be used for the determination of protein sequence. Mass spectroscopy can also be used in many other fields.
2. Which among the following is an analytical technique that measures the mass-to-charge ratio of ions?
A. Atomic spectroscopy
B. NMR spectroscopy
C. Infrared spectroscopy
D. Mass spectroscopy
Answer: D
Clarification: Mass spectroscopy is an analytical technique that measures the mass-to-charge ratio of ions. Atomic spectroscopy, infrared spectroscopy, and NMR spectroscopy do not measure the mass-to-charge ratio of ions.
3. A mass spectrum is a plot of the ion signal as a function of the mass-to-charge ratio.
A. False
B. True
Answer: B
Clarification: The above statement is true. A mass spectrum is a plot of the ion signal as a function of the mass-to-charge ratio. These spectra are used to determine the elemental or isotopic signature of a sample.
4. Which of the following analytical technique can be used to identify a chemical substance by the sorting of gaseous ions in electric and magnetic fields according to their mass-to-charge ratios?
A. Raman spectroscopy
B. Atomic spectroscopy
C. NMR spectroscopy
D. Mass spectroscopy
Answer: D
Clarification: Mass spectroscopy is an analytical technique that can be used to identify a chemical substance by the sorting of gaseous ions in electric and magnetic fields according to their mass-to-charge ratios. Whereas, Raman spectroscopy, atomic spectroscopy, and NMR spectroscopy cannot be used to identify a chemical substance by the sorting of gaseous ions in electric and magnetic fields according to their mass-to-charge ratios.
5. Mass spectrometers operate on the principle that moving ions may be deflected by an electric and magnetic field.
A. False
B. True
Answer: B
Clarification: The above statement is true. Mass spectrometers operate on the principle that moving ions may be deflected by an electric and magnetic field. Results in these techniques are displayed as spectra of the signal intensity of detected ions as a function of the mass-to-charge ratio.
6. Which of the following is not a component of mass spectrometric technique?
A. Ion source
B. Analyzer
C. Detector
D. X – ray source
Answer: D
Clarification: X – ray source is not a component of mass spectrometric technique. Whereas, Ion source, analyzer, and detector are the components of the mass spectrometric technique. In ion source, a beam of charged particles characteristic of the sample is produced.
7. Which component of the mass spectrometers separates the ion beams into its components?
A. Sample handling system
B. Ion source
C. Detector
D. Analyzer
Answer: D
Clarification: The component of the mass spectrometers that separates the ion beams into its components is called an analyzer. The detector collects or observes the separated ion beams. The sample handling system, ion source, and detector do not separate the ion beams into its components.
8. Which component of the mass spectrometers produces a beam of charged particles characteristic of the sample?
A. Radiation source
B. Analyzer
C. Detector
D. Ion source/ Ionizer
Answer: D
Clarification: The component of the mass spectrometers that produces a beam of charged particles characteristic of the sample is known as Ion source/ Ionizer. The radiation source, analyzer, and detector do not produce a beam of charged particles characteristic of the sample.
9. Monoisotopic mass is the sum of masses for the most abundant isotope of each element in amino acid.
A. False
B. True
Answer: B
Clarification: The above statement is true. Monoisotopic mass is the sum of masses for the most abundant isotope of each element in amino acid. In this monoisotopic mass, only the masses of the most abundant isotope of each element present in the amino acid residue is added.
10. The average mass is the average of the isotopic masses of each element weighed for the isotopic abundance.
A. False
B. True
Answer: B
Clarification: The above statement is true. The average mass is the average of the isotopic masses of each element weighed for the isotopic abundance. Therefore, in average mass the average of the isotopic masses of each element weighed for the isotopic abundance is added.
11. What is the monoisotopic mass of glycine?
Given data: Mass of the most abundant isotope of Carbon (C°)=12.0000,
Mass of most abundant isotope of Hydrogen (H°)=1.0078,
Mass of most abundant isotope of Oxygen (O°)=15.9949,
Mass of most abundant isotope of Nitrogen (N°)=14.0031.
A. 99.0687
B. 87.2365
C. 57.052
D. 57.0214
Answer: D
Clarification: The monoisotopic mass of glycine is 57.0214.
The chemical formula of Glycine is C2H3ON
Formula:
Monoisotopic mass
=[no. of carbon atoms x (C°) + no. of hydrogen atoms x (H°)
+ no. of oxygen atoms x (O°) + no. of nitrogen atoms x (N°)]
Hence, the monoisotopic mass of glycine=2 x (12.000) + 3 x (1.0078) + (15.9949) + (14.0031)
monoisotopic mass of glycine = 57.0214.
12. What is the average mass of glycine?
Given data: Average mass of Carbon (C.=12.011,
The average mass of Hydrogen (H)=1.008,
The average mass of Oxygen (O)=15.999,
The average mass of Nitrogen (N)=14.007.
A. 87.0320
B. 99.0656
C. 57.021
D. 57.052
Answer: D
Clarification: The average mass of glycine is 57.052.
The chemical formula of Glycine is C2H3ON
Formula:
Average mass=[no. of carbon atoms x (C. + no. of hydrogen atoms x (H)
+ no. of oxygen atoms x (O) + no. of nitrogen atoms x (N)]
Hence, the Average mass of glycine=2 x (12.011) + 3 x (1.008) + (15.999) + (14.007)
The average mass of glycine=57.052.
13. ESI and MALDI belong to which of the following techniques?
A. Detection
B. Analysis
C. Acceleration
D. Ionization
Answer: D
Clarification: ESI and MALDI are the techniques for ionization step in mass spectrometry. ESI stands for Electrospray ionizer, and MALDI stands for Matrix-Assisted Laser Desorption/Ionization. Both of the techniques generate ions in the gaseous phase.
14. Which of the following is not an ionization technique?
A. MALDI
B. ESI
C. FAB
D. HPLC
Answer: D
Clarification: HPLC is not an ionization technique. HPLC stands for High-Performance Liquid Chromatography. MALDI, ESI, and FAB are not ionization techniques. FAB is Fast Atom Bombardment.
15. Which of the following is a sample inlet technique?
A. MALDI
B. TOF
C. ESI
D. GC/HPLC
Answer: D
Clarification: GC/HPLC is a sample inlet technique in mass spectrometry. GC is Gas Chromatography and HPLC is High-Performance Liquid Chromatography. MALDI, TOF, and ESI are not sampling inlet techniques. TOF is Time Of Flight.