Advanced Analytical Separation And Blotting Techniques Assessment Practice Tests

Question 1

A protein migrates 4.0 cm in a 10% polyacrylamide gel, while a standard protein of $60	ext{ kDa}$ migrates 2.0 cm. Given the linear relationship $\log_{10}(MW) = m \cdot d + c$, where $d$ is migration distance, if the slope $m = -0.15	ext{ cm}^{-1}$ and the intercept $c = 5.0$, calculate the molecular mass of the unknown protein in kDa.

Accepted Answer

15.85 kDa

Question 2

In an IEF experiment, a protein with a $pI = 6.5$ is placed in a buffer at $pH = 4.0$. Determine the direction of migration and the net charge state of the protein.

Accepted Answer

The protein will migrate toward the cathode and carries a net positive charge.

Answer

The protein will migrate toward the anode and carries a net negative charge.

Answer

The protein will migrate toward the anode and carries a net positive charge.

Answer

The protein will migrate toward the cathode and carries a net negative charge.

Question 3

In a Western Blotting procedure, the primary purpose of incubating the membrane with a blocking agent like Bovine Serum Albumin (BSA) is to increase the binding affinity of the primary antibody to the target protein.

Accepted Answer

False

Answer

True

Question 4

A researcher performs IEF on a protein mixture. Protein A has a $pI$ of 5.2, Protein B has a $pI$ of 7.4, and Protein C has a $pI$ of 8.9. If the gel is established with a pH gradient from 4.0 to 10.0, calculate the relative order of the proteins from the anode (+) to the cathode (-).

Accepted Answer

Protein A, Protein B, Protein C

Question 5

Which of the following factors directly influence the resolution of protein separation in SDS-PAGE?

Answer

Acrylamide concentration

Answer

Cross-linker ratio

Answer

Voltage gradient

Answer

Protein color

Question 6

If a protein has a molecular mass of $100	ext{ kDa}$ and is analyzed on a gel where the migration distance $d$ is related to $\log_{10}(MW)$ by $d = -2.5 \cdot \log_{10}(MW) + 12.5$, calculate the migration distance $d$ in cm.

Accepted Answer

7.5 cm

Question 7

When designing a Western Blot for an enzyme, which step is critical to ensure that the enzyme remains detectable in situ?

Accepted Answer

Avoiding harsh denaturing conditions during the transfer process.

Answer

Using a high concentration of SDS in the transfer buffer.

Answer

Increasing the temperature to 95°C during the blocking step.

Answer

Using a membrane with high non-specific binding capacity.

Question 8

In an HPLC system, if the void volume $V_m$ is $1.2\, mL$ and the retention volume $V_r$ of a solute is $3.6\, mL$, calculate the capacity factor $k$.

Accepted Answer

2

Question 9

For a chromatographic column with a plate height $H = 0.05\, mm$ and a column length $L = 150\, mm$, determine the theoretical plate number $N$.

Accepted Answer

Option A

Answer

Option B

Answer

Option C

Answer

Option D

Question 10

In a Reverse Phase HPLC experiment, a mixture of three compounds (A: non-polar, B: moderately polar, C: highly polar) is injected. Predict the elution order using a water/acetonitrile gradient.

Accepted Answer

Option A

Answer

Option B

Answer

Option C

Answer

Option D

Question 11

In an IMAC purification, a protein with a polyhistidine tag is bound to a $Ni^{2+}$ column. If the binding equilibrium is represented by $Protein + Ni^{2+} \rightleftharpoons Protein-Ni^{2+}$, explain the effect of adding a high concentration of imidazole on the elution of the protein.

Accepted Answer

Competitive elution

Question 12

Given two peaks with retention times $t_{r1} = 10.0\, min$ and $t_{r2} = 12.0\, min$, and peak widths at the base $w_1 = 0.8\, min$ and $w_2 = 1.0\, min$, calculate the resolution $R_s$.

Accepted Answer

Option A

Answer

Option B

Answer

Option C

Answer

Option D

Question 13

If the selectivity factor $\alpha$ between two peaks is $1.0$, the peaks can be separated regardless of the efficiency $N$ of the column.

Accepted Answer

False

Answer

True

Question 14

Calculate the required plate number $N$ to achieve a resolution $R_s = 1.5$ for two peaks with a selectivity factor $\alpha = 1.1$ and a capacity factor $k = 2.0$.

Accepted Answer

18000

Question 15

A capillary column has a length of $30\,m$ and an inner diameter of $0.25\,mm$. If the plate height $H$ is calculated as $0.20\,mm$, determine the total number of theoretical plates $N$ for this column using the relationship $N = \frac{L}{H}$.

Accepted Answer

150,000

Answer

15,000

Answer

6,000

Answer

60,000

Question 16

A polar steroid molecule has a high boiling point and strong intermolecular hydrogen bonding, preventing it from eluting in the gas phase. Calculate the required molar mass increase if the molecule is derivatized by adding three Trimethylsilyl (TMS) groups, each with a mass of $73.14\,g/mol$.

Accepted Answer

219.42 g/mol

Question 17

In a comparative study, a packed column provides a capacity factor $k' = 5$ and a capillary column provides $k' = 2$. If the mobile phase flow rate is constant, which column will exhibit a shorter retention time $t_R$ for a given analyte, assuming $t_R = t_M(1 + k')$ where $t_M$ is the dead time?

Accepted Answer

The capillary column

Answer

The packed column

Answer

Both have the same retention time

Answer

Cannot be determined without $t_M$

Question 18

An analyst needs to detect trace amounts of sulfur-containing pesticides in a complex soil matrix. Which detector provides the highest selectivity and sensitivity for this specific application?

Accepted Answer

Flame Photometric Detector (FPD)

Answer

Thermal Conductivity Detector (TCD)

Answer

Flame Ionization Detector (FID)

Answer

Mass Spectrometry (MS)

Question 19

In a Flame Ionization Detector (FID), the response is proportional to the number of oxidizable carbon atoms in the analyte, meaning the detector is considered a mass-flow sensitive detector.

Accepted Answer

True

Answer

False

Question 20

In GC-MS, an analyte produces a molecular ion peak at $m/z = 150$ and a base peak at $m/z = 91$. Calculate the mass of the neutral fragment lost during the formation of the base peak.

Accepted Answer

59

Advanced Analytical Separation And Blotting Techniques Assessment Practice Tests

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Advanced Analytical Separation and Blotting Techniques Assessment

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