Question

Identify the correct sequence for DNA extraction : A. Phenol-chloroform mixture is added to separate proteins from DNA.
B. Double stranded DNA molecules are transferred for analysis.
C. Unwanted proteins or cellular debris are separated by centrifugation.
D. SDS and Proteinase K are added to break open the cell membrane.
Choose the correct answer from the options given below :

• A. A, B, C, D
• B. C, A, B, D
• C. D, A, C, B
• D. B, C, A, D

Hint:

DNA extraction flow: Lysis → Protein removal → Separation → DNA collection.

Answer 1

The Correct Option is C

Concept: DNA extraction is a stepwise process used to isolate DNA from cells. It involves cell lysis, removal of proteins and contaminants, and purification of DNA.

Step 1: Cell lysis (D).
SDS (detergent) and Proteinase K are added to break down cell membranes and proteins, releasing DNA into solution.

Step 2: Protein removal (A).
Phenol-chloroform is added to separate proteins from DNA. Proteins dissolve in organic phase while DNA remains in aqueous phase.

Step 3: Centrifugation (C).
The mixture is centrifuged to separate different components into layers, allowing removal of unwanted debris.

Step 4: DNA collection (B).
Finally, purified double-stranded DNA is collected and transferred for further analysis.

Step 5: Forming correct sequence.
\[ D \rightarrow A \rightarrow C \rightarrow B \] Final Conclusion:
Hence, the correct answer is option (3).