A 19-year-old from Wayanad with painful crises has hemoglobin electrophoresis at pH 8.6. The main band runs slower than Hb A. Why does Hb S move more slowly than Hb A?

Valine replaces glutamic acid at beta-6

Lysine replaces glutamic acid at beta-6

Hb S polymerizes in the alkaline buffer

Hb S has a larger molecular weight

Compared with filter paper, cellulose acetate as an electrophoresis support has the advantage of:

Faster runs with less protein adsorption

Higher resolution of DNA fragments

Electrophoresis

24 Kerala PSC Lab Technician Gr II practice questions on Electrophoresis, part of Biochemistry. The first 24 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Medium
A 19-year-old from Wayanad with painful crises has hemoglobin electrophoresis at pH 8.6. The main band runs slower than Hb A. Why does Hb S move more slowly than Hb A?
1. ALysine replaces glutamic acid at beta-6
2. BHb S polymerizes in the alkaline buffer
3. CValine replaces glutamic acid at beta-6
4. DHb S has a larger molecular weight
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Answer: C · Valine replaces glutamic acid at beta-6
In Hb S, neutral valine replaces negatively charged glutamic acid at position 6 of the beta chain. Each hemoglobin molecule loses two negative charges, so at pH 8.6 it moves less far toward the anode than Hb A. Hb C, with lysine at the same position, moves even more slowly. Hb D and Hb G run with Hb S at alkaline pH, so a solubility test or acid (pH 6.2) electrophoresis confirms it.
- A: Lysine at beta-6 is Hb C, which runs slower than Hb S.
- B: Hb S polymerizes when deoxygenated in red cells, not during electrophoresis.
- D: The single amino acid change hardly alters the size of the molecule.
Question 2 · Hard
A 55-year-old man with long-standing alcohol use has serum protein electrophoresis showing low albumin, a broad polyclonal rise in gamma globulin and beta-gamma bridging. The most likely diagnosis is:
1. ACirrhosis of the liver
2. BAcute bacterial infection
3. CNephrotic syndrome
4. DMultiple myeloma
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Answer: A · Cirrhosis of the liver
The damaged liver makes less albumin, so the albumin band is low. Immunoglobulins rise polyclonally, and IgA, which runs between beta and gamma, fills the gap between the bands to give beta-gamma bridging. Myeloma gives a narrow monoclonal band, not a broad rise. Nephrotic syndrome gives low albumin with a high alpha-2 band and low gamma globulin, and an acute bacterial infection raises the alpha-1 and alpha-2 bands.
- B: Acute infection raises the alpha-1 and alpha-2 acute-phase proteins.
- C: Nephrotic syndrome raises alpha-2 and lowers gamma globulin.
- D: Myeloma gives a narrow monoclonal band, not a broad polyclonal rise.
Question 3 · Easy
On agarose lipoprotein electrophoresis of a non-fasting sample, which fraction stays at the point of application?
1. ABeta (LDL)
2. BAlpha (HDL)
3. CChylomicrons
4. DPre-beta (VLDL)
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Answer: C · Chylomicrons
Chylomicrons are very large particles with little protein, so they hardly move and stay at the origin. HDL runs farthest, in the alpha position, followed by VLDL (pre-beta) and LDL (beta). Chylomicrons are normally absent after a 12-hour fast. A band at the origin in a fasting sample suggests type I or type V hyperlipoproteinemia.
- A: LDL moves to the beta position.
- B: HDL moves farthest, to the alpha position.
- D: VLDL moves to the pre-beta position, ahead of LDL.
Question 4 · Medium
Compared with filter paper, cellulose acetate as an electrophoresis support has the advantage of:
1. AHigher resolution of DNA fragments
2. BFaster runs with less protein adsorption
3. CSeparation by molecular size
4. DNo need for staining the bands
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Answer: B · Faster runs with less protein adsorption
Filter paper is fibrous and adsorbs proteins, which causes trailing, and a run takes many hours. Cellulose acetate is a uniform microporous film with little adsorption, so serum proteins separate in under an hour with a small sample. The strip can be made transparent for scanning by densitometry. It separates by charge, not size, and the bands still have to be stained, for example with Ponceau S.
- A: DNA fragments are separated in agarose or polyacrylamide gels.
- C: Cellulose acetate separates by charge; size sieving needs polyacrylamide.
- D: The protein bands still need staining to be seen.
Question 5 · Easy
In serum protein electrophoresis on cellulose acetate at pH 8.6, which fraction moves farthest toward the anode?
1. AAlbumin
2. BGamma globulin
3. CBeta globulin
4. DAlpha-1 globulin
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Answer: A · Albumin
At pH 8.6 the serum proteins are above their isoelectric points and carry a negative charge. Albumin has the lowest isoelectric point and the greatest negative charge for its size, so it moves fastest toward the anode. The order from the anode is albumin, alpha-1, alpha-2, beta and gamma globulin. Gamma globulins stay near the point of application.
- B: Gamma globulin moves least and stays near the origin.
- C: Beta globulin runs between alpha-2 and gamma.
- D: Alpha-1 globulin runs just behind albumin.
Question 6 · Medium
After a head injury, a man has clear fluid dripping from his nose. Which protein, shown by electrophoresis with immunofixation, confirms that the fluid is CSF?
1. ABeta-2 microglobulin
2. BBeta-2 transferrin
3. CMyelin basic protein
4. DAlpha-1 antitrypsin
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Question 7 · Easy
Which stain is commonly used to show serum protein bands on cellulose acetate?
1. AOil Red O
2. BPonceau S
3. CSudan black B
4. DEthidium bromide
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Question 8 · Hard
For a 24-year-old woman with MCV 64 fL and normal ferritin, HbA2 is estimated after cellulose acetate electrophoresis. The A2 band is eluted into 3.0 mL and reads 0.120 at 415 nm; the A band is eluted into 15.0 mL and reads 0.390. What is the HbA2 percentage?
1. A5.8%
2. B23.5%
3. C30.8%
4. D6.2%
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Question 9 · Easy
In zone electrophoresis, which factor makes a protein migrate faster?
1. AGreater net charge on the protein
2. BGreater viscosity of the medium
3. CLarger size of the protein
4. DHigher ionic strength of the buffer
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Question 10 · Medium
On alkaline (pH 8.6) cellulose acetate electrophoresis, which hemoglobin runs in the same position as Hb A2?
1. AHb F
2. BHb E
3. CHb S
4. DHb H
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Question 11 · Medium
On alkaline electrophoresis, Hb S and Hb D run in the same position. Which method separates them?
1. AOsmotic fragility test
2. BAlkali denaturation test
3. CRepeat cellulose acetate, pH 8.6
4. DAcid citrate agar electrophoresis, pH 6.2
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Question 12 · Easy
After lipoprotein electrophoresis on agarose, the bands are made visible with a fat stain such as:
1. ASudan black B
2. BAmido black 10B
3. CCoomassie blue
4. DPonceau S
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Question 13 · Hard
A patient's total serum protein is 8.4 g/dL. Densitometry of the electrophoresis strip gives: albumin 40%, alpha-1 4%, alpha-2 9%, beta 11%, gamma 36%. What is the gamma globulin concentration?
1. A3.0 g/dL
2. B2.2 g/dL
3. C0.36 g/dL
4. D3.4 g/dL
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Question 14 · Hard
A 22-year-old woman has Hb 11.2 g/dL, RBC 5.9 million/µL, MCV 63 fL, MCH 19 pg and normal ferritin. Alkaline electrophoresis shows Hb A with an A2-position band of 5.2% (reference 1.5-3.5%) and Hb F 1.2%. The most likely diagnosis is:
1. AAlpha-thalassemia trait
2. BHb E trait
3. CIron deficiency anemia
4. DBeta-thalassemia trait
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Question 15 · Medium
In SDS-polyacrylamide gel electrophoresis, proteins separate mainly by molecular weight because SDS:
1. AGives all proteins a uniform negative charge
2. BBinds proteins by their isoelectric point
3. CStains proteins as they move
4. DMakes all proteins neutral
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Question 16 · Easy
A sharp, narrow, dense band in the gamma region of serum protein electrophoresis most often indicates:
1. ALiver cirrhosis
2. BNephrotic syndrome
3. CAcute infection
4. DMultiple myeloma
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Question 17 · Medium
Why do alpha-1 and alpha-2 bands rise on electrophoresis in acute inflammation?
1. AAlbumin moves into them
2. BThey hold lipoproteins
3. CThey contain acute-phase proteins
4. DThey contain immunoglobulins
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Question 18 · Easy
At pH 8.6, serum proteins move toward the anode because at this pH they:
1. ACarry a net positive charge
2. BAre fully denatured
3. CCarry a net negative charge
4. DHave no net charge
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Question 19 · Easy
Normal serum protein electrophoresis on cellulose acetate shows how many main fractions?
1. AThree
2. BSeven
3. CFive
4. DTwo
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Question 20 · Easy
After a serum protein electrophoresis strip is stained and cleared, it is scanned with a densitometer to:
1. AMeasure the total protein
2. BIdentify the immunoglobulin class
3. CMeasure each fraction's percentage
4. DFind each protein's isoelectric point
Answer and explanation in LearnFree account
Question 21 · Medium
A child with heavy proteinuria and edema is most likely to show which serum protein electrophoresis pattern?
1. ALow albumin with a raised gamma band
2. BLow albumin with a raised alpha-2 band
3. CNormal albumin with a gamma spike
4. DNormal albumin with a low alpha-1 band
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Question 22 · Medium
A protein electrophoresis run on heparinised plasma instead of serum shows an extra band between beta and gamma. This band is:
1. ABence Jones protein
2. BC-reactive protein
3. CFibrinogen
4. DTransferrin
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Question 23 · Hard
A newborn from Wayanad is screened because both parents have sickle cell trait. Cord blood electrophoresis shows Hb F and Hb S, with no Hb A. The most likely diagnosis is:
1. ABeta-thalassemia trait
2. BNormal newborn
3. CSickle cell anemia
4. DSickle cell trait
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Question 24 · Medium
In isoelectric focusing, proteins are separated according to their:
1. ASolubility in salt
2. BLipid content
3. CMolecular weight
4. DIsoelectric point
Answer and explanation in LearnFree account

Electrophoresis

A 19-year-old from Wayanad with painful crises has hemoglobin electrophoresis at pH 8.6. The main band runs slower than Hb A. Why does Hb S move more slowly than Hb A?

A 55-year-old man with long-standing alcohol use has serum protein electrophoresis showing low albumin, a broad polyclonal rise in gamma globulin and beta-gamma bridging. The most likely diagnosis is:

On agarose lipoprotein electrophoresis of a non-fasting sample, which fraction stays at the point of application?

Compared with filter paper, cellulose acetate as an electrophoresis support has the advantage of:

In serum protein electrophoresis on cellulose acetate at pH 8.6, which fraction moves farthest toward the anode?

After a head injury, a man has clear fluid dripping from his nose. Which protein, shown by electrophoresis with immunofixation, confirms that the fluid is CSF?

Which stain is commonly used to show serum protein bands on cellulose acetate?

For a 24-year-old woman with MCV 64 fL and normal ferritin, HbA2 is estimated after cellulose acetate electrophoresis. The A2 band is eluted into 3.0 mL and reads 0.120 at 415 nm; the A band is eluted into 15.0 mL and reads 0.390. What is the HbA2 percentage?

In zone electrophoresis, which factor makes a protein migrate faster?

On alkaline (pH 8.6) cellulose acetate electrophoresis, which hemoglobin runs in the same position as Hb A2?

On alkaline electrophoresis, Hb S and Hb D run in the same position. Which method separates them?

After lipoprotein electrophoresis on agarose, the bands are made visible with a fat stain such as:

A patient's total serum protein is 8.4 g/dL. Densitometry of the electrophoresis strip gives: albumin 40%, alpha-1 4%, alpha-2 9%, beta 11%, gamma 36%. What is the gamma globulin concentration?

A 22-year-old woman has Hb 11.2 g/dL, RBC 5.9 million/µL, MCV 63 fL, MCH 19 pg and normal ferritin. Alkaline electrophoresis shows Hb A with an A2-position band of 5.2% (reference 1.5-3.5%) and Hb F 1.2%. The most likely diagnosis is:

In SDS-polyacrylamide gel electrophoresis, proteins separate mainly by molecular weight because SDS:

A sharp, narrow, dense band in the gamma region of serum protein electrophoresis most often indicates:

Why do alpha-1 and alpha-2 bands rise on electrophoresis in acute inflammation?

At pH 8.6, serum proteins move toward the anode because at this pH they:

Normal serum protein electrophoresis on cellulose acetate shows how many main fractions?

After a serum protein electrophoresis strip is stained and cleared, it is scanned with a densitometer to:

A child with heavy proteinuria and edema is most likely to show which serum protein electrophoresis pattern?

A protein electrophoresis run on heparinised plasma instead of serum shows an extra band between beta and gamma. This band is:

A newborn from Wayanad is screened because both parents have sickle cell trait. Cord blood electrophoresis shows Hb F and Hb S, with no Hb A. The most likely diagnosis is:

In isoelectric focusing, proteins are separated according to their: