This set of Gene Manipulation Interview Questions and Answers for freshers focuses on “Basic Laboratory Techniques – 4”.
1. Which nylon membranes should be used in southern blotting to reduce the need for gel pretreatment?
Explanation: An alternative method is to use positively charged nylon membranes, which removes the need for extended gel pretreatment.
2. What is the native form of DNA?
c) Small size
d) Composite form
Explanation: The native form of the DNA is the one in which all inter and intra bonds are intact in the helical structure of the DNA.
3. Nitrocellulose is flammable in nature.
Explanation: Due to the flammable nature of nitrocellulose and also the nitrocellulose membrane, the baking of the nitrocellulose is done in a vacuum oven.
4. Thymine residues in the DNA and positively charged amino groups on the surface of nylon membranes ___________
a) Are of same size
b) Are of same charge
Explanation: A fixation method is based on ultraviolet cross-linking. It is based on the formation of cross-links between thymine groups of DNA and positive amino groups on nitrocellulose membrane.
5. How can the fixation period be determined initially?
b) Calibration experiment
d) UV analysis
Explanation: A calibration experiment must be performed to determine the optimal fixation period. This fixation period can then be utilized in subsequent experiments.
6. Following the fixation step in blotting, the membrane is placed in RNA or DNA sequence which is _____________ to blot-transferred DNA.
c) Larger in size
Explanation: Following the fixation step, the membrane is placed in a solution of labeled RNA or single-stranded DNA or oligodeoxynucleotide which is complementary in sequence to the blot-transferred DNA.
7. The labeled nucleic acid used for detection is called _________
Explanation: Conditions are chosen so that the labeled nucleic acid hybridizes with the DNA on the membrane. Since the labeled nucleic acid is used to detect and locate the complementary sequence, it is called the probe.
8. The labeled nucleic acid _________ with DNA sample to be analyzed.
Explanation: The labeled nucleic acid acts as a probe. The main function of this nucleic acid is to hybridize with the given DNA or RNA sample.
9. Which film is used in southern blotting?
a) UV film
b) Radiography film
c) X-ray film
d) Cellulose film
Explanation: After the hybridization reaction has been carried out, the membrane is washed to remove unbound radioactivity and regions of hybridization are detected autoradiographically by placing the membrane in direct contact with X-ray film.
10. Lower ionic strength is an example of increased stringency in southern blotting.
Explanation: The hybridization can be carried out in conditions of relatively low stringency which permit a high rate of hybridization, followed by a series of high stringencies such as high temperature and low ionic strength.
11. Which of the following will reveal any of the imperfectly hybridized DNA samples?
a) Membrane separation
c) UV radiation
d) Infrared radiation
Explanation: Autoradiography following each washing stage will reveal any DNA bands that are related to, but not perfectly complementary, the probe and will also permit an estimate of the degree of mismatching to be made.
12. The Southern Blotting methodology is extremely _____________
Explanation: The southern blotting can be extremely sensitive. It can be applied to mapping restriction sites around a single-copy gene sequence.
13. Mini-satellite probes in Southern blotting can be used in ______________
a) DNA forensics
Explanation: When mini-satellite probe is used in Southern blotting, it can be applied forensically to minute amounts of DNA.
14. Northern blotting is used for _______
Explanation: Northern blotting technique is a variant of southern blotting technique and is used exclusively for RNA analysis.
15. Which of the following techniques can be used for RNA analysis?
c) Southern blotting
d) Northern blotting
Explanation: Southern’s technique is of enormous value but cannot be used for RNA analysis because RNA was found not to bind with nitrocellulose.
Sanfoundry Global Education & Learning Series – Vector Biology & Gene Manipulation.
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