Biophysical Miscellaneous
- In transmission electron microscopy, electron opacity is greatly enhanced by treating the specimen with
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In transmission electron microscope, to increase the electron opacity samples are impregnated with heavy metals such as uranyl acetate. Uranyl acetate is a water-soluble uranium compound and is often used as stains in electron microscopy.
Correct Option: B
In transmission electron microscope, to increase the electron opacity samples are impregnated with heavy metals such as uranyl acetate. Uranyl acetate is a water-soluble uranium compound and is often used as stains in electron microscopy.
- If the dissociation constant for solute-adsorbent binding is KD, the retention time of the solute in a chromatography column
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Chromatography involves a sample (or sample extract) being dissolved in a mobile phase (which may be a gas, a liquid or a supercritical fluid). The mobile phase is then forced through an immobile, immiscible stationary phase. The distribution of analytes between phases can often be described quite simply. An analyte is in equilibrium between the two phases ;
Amobile ⇔ Astationary
The time between sample injection and an analyte peak reaching a detector at the end of the column is termed the retention time (tR).
The dissociation constant for solute-adsorbent binding is KD. So, KD is indirectly proportional to the retention time of the column. So, retention time (tR) of a column decreases with increasing KD value.Correct Option: B
Chromatography involves a sample (or sample extract) being dissolved in a mobile phase (which may be a gas, a liquid or a supercritical fluid). The mobile phase is then forced through an immobile, immiscible stationary phase. The distribution of analytes between phases can often be described quite simply. An analyte is in equilibrium between the two phases ;
Amobile ⇔ Astationary
The time between sample injection and an analyte peak reaching a detector at the end of the column is termed the retention time (tR).
The dissociation constant for solute-adsorbent binding is KD. So, KD is indirectly proportional to the retention time of the column. So, retention time (tR) of a column decreases with increasing KD value.
- Match the entries in the Group I with the elution conditions in Group II.
Group I
P.Ion-exchange
Q.Hydrophobic chromatography
R.Gel filtration column chromatography
S.Chromatofocusing
Group II
1.Isocratic solvent chromatography
2.Ampholytes
3.Increasing gradient of salt
4.Decreasing gradient of polarity
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In Ion exchange chromatography, be it cation based or anion based resin used, the elution of the substrate bound to the resins is done through increasing concentrations of salt in a stepwise gradient form of elution. For Hydrophobic column chromatography, ligands bound to the column through various interactions can be eluted by decreasing the level of polarity in the solution. In Gel filtration chromatography, molecules elute based on their different molecular weights through the process of sieving from the column by the use of any kind of isocratic solution of particular pH. In Chromatofocusing or also known as Isoelectric focussing, samples of proteins are precipitated at the isoelectric point using ampholytes of different charges.
Correct Option: C
In Ion exchange chromatography, be it cation based or anion based resin used, the elution of the substrate bound to the resins is done through increasing concentrations of salt in a stepwise gradient form of elution. For Hydrophobic column chromatography, ligands bound to the column through various interactions can be eluted by decreasing the level of polarity in the solution. In Gel filtration chromatography, molecules elute based on their different molecular weights through the process of sieving from the column by the use of any kind of isocratic solution of particular pH. In Chromatofocusing or also known as Isoelectric focussing, samples of proteins are precipitated at the isoelectric point using ampholytes of different charges.
- A protein is to be purified using ion- exchange column chromatography. The relationship between HETP (Height Equivalent to Theoretical Plate) and the linear liquid velocity of mobile phase is given by :
H = A + Bu + C u
where H is HETP (m) and u is linear liquid velocity of mobile phase (m.s–1). The values of A, B and C are 3 × 10–8 m2.s–1, 3 s and 6 × 10–5 m, respectively. The number of theoretical plates based on minimum HETP for a column of 66 cm length will be ___________.
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(i)
H = A + Bu + C u
The minimum HETP occurs when
u = √A / B = 10–4 m / sec
A = 3 × 10–8 m2 / sec
B = 3 sec
C = 6 × 10–5 m
(ii) ∴ H = 6.6 × 10–4
Now, = 6.6 × 10–2 cm
(iii)H = L , N = No. of theoretical plates N
L = Length of the column∴ H = L N = 66 cm = 1000 6.6 × 10-2 cm
Correct Option: C
(i)
H = A + Bu + C u
The minimum HETP occurs when
u = √A / B = 10–4 m / sec
A = 3 × 10–8 m2 / sec
B = 3 sec
C = 6 × 10–5 m
(ii) ∴ H = 6.6 × 10–4
Now, = 6.6 × 10–2 cm
(iii)H = L , N = No. of theoretical plates N
L = Length of the column∴ H = L N = 66 cm = 1000 6.6 × 10-2 cm
- The helix content of a protein can be determined using
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The helix content of a protein can be determined using – circular dichromism spectroscopy. CD spectrum of unknown protein = A * [% alpha-helical] + B * [% beta-sheet] + C * [% random coil]
Correct Option: C
The helix content of a protein can be determined using – circular dichromism spectroscopy. CD spectrum of unknown protein = A * [% alpha-helical] + B * [% beta-sheet] + C * [% random coil]
