Gene Manipulation Questions and Answers for Freshers focuses on “Basic Laboratory Techniques – 2”.
1. The technique of sucrose gradients was later superseded by __________
A. Electroporation
B. Electrodialysis
A. Gel electrophoresis
D. Biolistics
Answer: C
Clarification: The first experiments of cutting and joining DNA were monitored by velocity sedimentation in sucrose gradient; this has been entirely superseded by gel electrophoresis.
2. Gel electrophoresis is not used as a purification technique.
A. True
B. False
Answer: B
Clarification: Gel electrophoresis is not only used as an analytical method, but it is also routinely used preparatively for the purification of DNA.
3. Polyacrylamide in Gel electrophoresis technique is preferred for _______________
A. Smaller DNA
B. Bigger chunks
A. Proteins
D. Sucrose
Answer: A
Clarification: Agarose is convenient for separating DNA fragments ranging a few hundred base pairs in size and polyacrylamide is preferred for smaller DNA fragments.
4. The average pore size of an agarose gel depends on _______________
A. Casting tray
B. Buffer composition
A. Amount
D. Protein
Answer: B
Clarification: An agarose gel is a complex network of polymeric molecules whose average pore size depends on the buffer composition.
5. DNA molecules in an electrophoresis gel exhibit which behavior?
A. Black body
B. Inelastic
A. Elastic
D. Reputation
Answer: C
Clarification: DNA molecules display elastic behavior by stretching in the direction of the applied field and then contracting into dense balls.
6. Molecules greater than what size cannot be separated without using electric field?
A. 1 kb
B. 2 kb
A. 10 kb
D. 20 kb
Answer: D
Clarification: With molecules about 20 kb in size, it is difficult to separate molecules without recourse to pulsed electric fields.
7. PFGE was developed in which year?
A. 1970
B. 1984
A. 1950
D. 1944
Answer: B
Clarification: In pulsed-field gel electrophoresis (PFGE), developed by Schwartz and Cantor 1984, molecules as large as 10 Mb can be separated in agarose gels.
8. In PFGE, the direction of DNA molecules is periodically ________
A. Hindered
B. Changed
A. Paused
D. Slowed
Answer: B
Clarification: The DNA is caused to periodically alter its direction of migration by regular changes in the orientation of electric field with respect to the gel.
9. Reorientation angle is difference between ____________
A. Migration direction
B. Field direction
A. Tray direction
D. Gel direction
Answer: A
Clarification: The difference between the directions of migration induced by each of the electric fields is the reorientation angle and corresponds to the angle that the DNA must turn as it changes its direction of migration each time the fields are switched.
10. Reorientation angle is the angle of ______________
A. DNA
B. Protein
A. Vector
D. Gel
Answer: A
Clarification: The reorientation angle corresponds to the angle that the DNA must turn as it changes its direction of migration each time the fields are switched.
11. Samples do not run in straight lines is a ________ of PFGE.
A. Advantage
B. Disadvantage
A. Cost efficiency
D. Ease
Answer: B
Clarification: A major disadvantage of PFGE is that the samples do not run in straight lines, which makes the subsequent analysis of samples difficult.
12. CHEF is a type of _____________
A. Vector
B. Gel
A. Electrophoresis
D. Gene
Answer: C
Clarification: The contour-clamped-homogeneous electric field electrophoresis (CHEF) solves the problems encountered in PFGE.
13. The reorientation angle used for yeast in CHEF is _____
A. 106⁰
B. 110⁰
A. 120⁰
D. 200⁰
Answer: A
Clarification: The reorientation angle can be varied in newer CHEF systems and it has been found that for whole yeast chromosomes the migration rate is fastest at 106⁰.
14. DNA fragments of several ________ can be handled using CHEF.
A. Tens
B. Hundreds
A. Thousands
D. Mixed
Answer: B
Clarification: DNA as large as 200-300 kb are routinely handled in genomics work and these can be separated in a matter of hours using CHEF.
15. Which reorientation angle is most suited in CHEF for DNA up to several hundred base pairs?
A. 100⁰
B. 90⁰
A. 200⁰
D. 300⁰
Answer: B
Clarification: DNA as large as 200-300 kb are routinely handled in genomics work and these can be separated in a matter of hours using CHEF.
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