Question

Which of the following is wrong
(a)The first transgenic cow Rosie, produced milk which was human alpha beta-lactam 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 the transfer of R-DNA into the host
(a)Statement (B) and (C )
(b)Statement (C ) and (D)
(c)Statement (A) and ( C)
(d)Statement (B) only

Answer 1

After endonucleases cut the DNA into small pieces, there is a technique used to separate fragments depending on the charge of the fragments.

Complete answer:
Restriction enzymes or restriction endonucleases are used to cut the DNA. This process is called restriction enzyme digestion. The cutting DNA by restriction enzymes results in the fragments of DNA. These fragments are isolated by the technique known as gel electrophoresis.
Ribonuclease enzymes are used to cut the DNA molecules and gel electrophoresis is used to isolate the DNA fragments.

Additional Information: -In 1977, the first transgenic cow, Rosie produced human protein-enriched milk that contains human alpha-lactalbumin. It is rich in essential amino acids and is the dominant protein in human milk.
-This milk was a nutritionally more balanced product for human babies than what is available in normal milk.
-In, the gel electrophoresis technique, DNA fragments are separated based upon their electric charge. As DNA is a negatively charged molecule, they can be separated by forcing them to move towards anode under an electric field through a medium matrix.
-After completion of the biosynthetic stage in R-DNA technology, the product has to be subjected through a series of processes which include separation and purification which are collectively called downstream processing.
-There are various methods of introducing the ligated DNA into recipient cells. Some of them are, microinjections, gene gun method, and disarmed pathogen vectors that are used to transfer R-DNA into the host.
So, the correct answer is ‘statement (b) only’.

Note: Restriction enzymes belong to a longer class of enzymes called nucleases which are of two kinds; exonucleases and endonucleases. Exonucleases remove nucleotides from the end of DNA whereas endonucleases make cuts at specific positions within DNA.