Question

Read statement a-d. Which two of them have mistakes?
(a) First transgenic buffalo, Rosie produced milk which was human alpha lactalbumin enriched.
(b) Restriction enzymes are used in isolation of DNA from other macromolecules.
(c) Downstream processing is one of the steps of r-DNA technology.
(d) Disarmed pathogen vectors are also used in transfer of r-DNA into the host.

• A. $b\text{and}c$
• B. $c\text{and}d$
• C. $a\text{and}c$
• D. $a\text{and}b$

Answer 1

The correct options are (a) and (b)

Explanation of the correct answers:

Option (a):

1. The first transgenic cow was Rosie, developed in 1997, in which the gene introduced was Human-alpha-lactalbumin milk at 2.4 grams per litre.
2. As a result, the milk produced had a better content of protein and was nutritionally more apt for human infants.
3. This was because the milk was a nutritionally more balanced product compared to the natural bovine milk and could be served to the elderly or babies having special digestive or nutritive requirements.
4. Hence, the statement given in question that Rosie was a first transgenic buffalo is wrong.
5. Rosie was a cow.

Option (b):

1. Restriction enzymes are the enzymes produced by certain bacteria that have the property of cleaving DNA molecule at or near specific base sequences.
2. So, it is used in isolation of a part of DNA from the whole DNA macromolecule.
3. It is not used to isolate DNA from other macromolecules.
4. Enzymes like proteinase K is used to separate out DNA from the other macromolecules like histone proteins.
5. So, the statement that restriction enzymes are used in isolation of DNA from other macromolecules is wrong.

Explanation of the incorrect answers:

Option (c):

1. Downstream processing refers to the series of unit operations used to isolate, purify and concentrate the product obtained by r DNA.
2. Downstream processing includes the separation and purification process.
3. Thus, downstream processing is one of the steps of r-DNA technology.

Option (d):

1. Disarmed pathogens are created by removing the genes that are responsible for virulence and adding genes of our interest instead so that when the disarmed pathogen is used to infect the host, it does not cause disease but transfers the recombinant DNA into the host.
2. Example is retrovirus vector.
3. Retroviruses have the ability to transform normal animal cells into cancerous cells.
4. Retroviruses have been disarmed and are now used to deliver desirable genes into animal cells.
5. Therefore, disarmed pathogen vectors are also used in transfer of r-DNA into the host.

Final answer: The two statements that first transgenic buffalo, Rosie produced milk which was human alpha lactalbumin enriched and restriction enzymes are used in isolation of DNA from other macromolecules are wrong.