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Step-by-Step Explanation
Step 1: Understand the Question
The question provides four statements about transgenic animals and recombinant DNA (rDNA) technology. We need to identify which two statements are erroneous.
Step 2: Examine Each Statement
Statement (A): "The first transgenic buffalo, Rosie, produced milk which was human alpha-lactalbumin enriched."
• The problem here is referring to "Rosie" as a buffalo. Historically, Rosie was a transgenic cow (not a buffalo) that produced milk enriched with human alpha-lactalbumin.
Statement (B): "Restriction enzymes are used in isolation of DNA from other macromolecules."
• Restriction enzymes are primarily used to cut DNA at specific recognition sites. The process of isolating DNA from macromolecules mainly uses different enzymes (e.g., lysozyme for bacterial cell walls, cellulase for plant cell walls, chitinase for fungal cell walls), along with other steps like detergent treatment and centrifugation. Thus, statement (B) is also incorrect as restriction enzymes are not the key enzymes for DNA isolation.
Statement (C): "Downstream processing is one of the steps of rDNA technology."
• This is correct because once products (proteins, enzymes, etc.) are formed using recombinant DNA, subsequent purification and packaging steps are called downstream processing.
Statement (D): "Disarmed pathogen vectors are also used in the transfer of rDNA into the host."
• This is also correct. Harmless (disarmed) viral or bacterial vectors can be used to deliver recombinant DNA into host cells.
Step 3: Identify the Two Erroneous Statements
From the analysis above, the two statements containing mistakes are (A) and (B).
Step 4: Detailed Reasoning
First Transgenic Cow: Rosie was a transgenic cow, not a buffalo. She produced human protein-enriched milk containing $\\alpha$-lactalbumin, which is nutritionally more balanced for human babies.
Use of Restriction Enzymes: Restriction enzymes (endonucleases) cut DNA at specific sites. DNA isolation, however, involves breaking cells open (using lysozyme, cellulase, or chitinase), removing proteins (proteases), and finally washing and separating the DNA. Restriction enzymes do not play a role in this isolation step.
Step 5: Conclusion
Therefore, "Statements (A) and (B)" are the ones with mistakes. The transgenic animal Rosie was actually a cow, and restriction enzymes are not used for the initial isolation of DNA from macromolecules.
