MCQ on DNA Extraction (BioTechnology)

1. For isolating DNA from plants, the most suitable method is

a) CTAB method
b) SDS-phenol extraction
c) SDS-proteinase K treatment
d) all of these

Answer: a) CTAB method

2. Which of the following reagent is commonly used for bacterial cell wall lysis

a) CTAB
b) phenol extraction
c) lysozyme
d) penicillin

Answer: c) lysozyme

3. DNA extraction from plant tissues are difficult due to

a) presence of large amount of DNA
b )presence of large amount of RNA along with DNA
c) both a and b
d )presence of secondary metabolites and polysaccharides

Answer: d ) presence of secondary metabolites and polysaccharides

4. The action of Cetyl Trimethyl Ammonium Bromide (CTAB) in DNA extraction from plant tissue is

a) CTAB complex with nucleic acids and form precipitate
b) CTAB complex with proteins and form precipitate
c) CTAB complex with polysaccharides and form precipitate
d) CTAB complex with secondary metabolites and form precipitate

Answer: a) CTAB complex with nucleic acids and form precipitate

5. Which of the following reagents are used for precipitating DNA

a) isopropanol
b) ethanol
c) both a and b
d) none of these

Answer: c) both a and b

6. The action of EDTA in EDTA-lysozyme treatment in bacterial DNA extraction is

a) removes Mg+ ions essential for maintenance of bacterial cell wall structure
b) inhibits degradation of DNA by cellular enzymes
c) removes outer lipopolusaccharide layer of Gram negative bacteria
d) all of these

Answer: d) all of these

7. Phenol used in DNA extraction 

a) precipitates DNA and leave proteins in aqueous solution
b) precipitates RNA-protein complex and leave DNA in aqueous solution
c) precipitates cell debris and leave nucleic acids-protein complex in aqueous solution
d) precipitates proteins and leave nucleic acids in aqueous solution

Answer: d) precipitates proteins and leave nucleic acids in aqueous solution

8. In cell extracts with high protein content, before phenol treatment

a) chloroform is used to break polypeptides to small fragments
b) SDS is used to break polypeptides to small fragments
c) Proteases are used to break polypeptides to small fragments
d) all of these

Answer: c) Proteases are used to break polypeptides to small fragments

9. Which of the following reagent is used for quantifying DNA

a) chloroform
b) CTAB
c) Diphenylamine
d) dansyl chloride

Answer: c) Diphenylamine

10. Which of the following is in the correct order regarding DNA extraction

a) RNAase treatment->Protease treatment->Cell lysis-> ethanol precipitation
b ) Cell lysis->phenol treatment->RNAase treatment-> ethanol precipitation
c) Cell lysis-> RNAase treatment ->protease treatment-> ethanol precipitation
d) Cell lysis-> phenol treatment ->protease treatment-> ethanol precipitation

Answer: b ) Cell lysis->phenol treatment->RNAase treatment-> ethanol precipitation


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