Insertion and ligation of dna - class-XII

The purified DNA, after treatment with various enzymes, precipitates out after addition of chilled ethanol. This is viewed as a collection of fine threads in the suspension, and is easily collected. The process is known as DNA spooling.

Insertional inactivation is the inactivation of a gene upon insertion of another gene inside in its place or within its coding sequence. This helps the selection of transformant and as well as recombinant colonies in selective antibiotic medium aided due to insertional inactivation of the antibiotic gene which becomes inactive due to foreign gene insert within its sequence. 

r-DNA technology is the process involving the introduction of a foreign piece DNA containing a gene of interest into the genome of an organism. Isolation and separation is a step in the process in which various techniques are used to separate the required gene (containing the gene of interest) from the nucleus of the cell (free of the other cellular contaminants). The isolated DNA is then restriction digested and amplified to make several copies. It is then inserted into a vector for transfer into an appropriate host. Elution is a step involved in the process of separation of DNA. So, the correct answer is 'isolation and separation'.

Escherichia coli (E. coli) is the most widely used host organism in genetic engineering due to its well-understood genetics and ease of culture.

Restriction endonucleases are enzymes that cleave the phosphodiester bonds between nucleotides within a polynucleotide chain. This bond breakage is achieved through the addition of a water molecule, which is a hydrolysis reaction.

The biolistic method, or gene gun technique, coats microscopic gold or tungsten particles with foreign DNA and accelerates them at high velocity into target cells. Microinjection directly injects DNA into the nucleus using a micropipette.

Trichoderma harzianum is a biofungicide and is used for suppression of various disease causing fungal pathogens. Penicillium expansum, blue mold, causes postharvest decay of stored apples and produces the carcinogenic mycotoxin patulin. Meloidogyne incognita, southern root-knot nematode" or the "cotton root-knot nematode", is a nematode with multiple hosts. Agrobacterium tumefaciens is a soil plant pathogenic bacterium that carries Ti plasmid. It can transfer a particular segment of the tumor-inducing (Ti) plasmid into the nucleus of infected cells. The transferred T-DNA is then integrated into the host genome and transcribed with it. This ability of Agrobacterium tumefaciens to transfer the T-DNA in host genome is explored in genetic engineering to transfer the desired DNA segment, carrying the gene of the interest, into genome of selected organisms. Option D is the correct answer. 

Ligase is nick named as 'molecular sutures'. In Biochemistry, ligase is defined as an enzyme that can catalyze the joining of two large molecules by forming a new chemical bond.

(A) Rosie was the first transgenic cow and its milk was rich in human alpha-lactalbumin protein.

Elution is the process of extracting DNA fragments from an agarose gel after they have been separated.

Crown gall disease is caused by Agrobacterium tumefaciens, which transfers a specific segment of its Ti plasmid (T-DNA) into the plant genome.

The correct chronological sequence of recombinant DNA technology steps is: first isolate the suitable plasmid (c), break the donor DNA using restriction enzymes (a), join the donor DNA with the plasmid using ligase to form recombinant DNA (e), insert the recombinant DNA into a host through cloning (d), and finally culture the transformed bacteria (b). This matches the sequence 1, 3, 5, 4, 2 if steps a, c, e, d, b correspond to those numbers.

Restriction enzymes cut DNA creating sticky ends of restriction fragments. While DNA ligase joins these sticky ends to form recombinant DNA. 

In insertional inactivation, the Z-gene (encoding beta-galactosidase) is disrupted. If the gene is intact, the bacteria produce the enzyme and turn blue on chromogenic substrate (non-recombinant). If the DNA segment is inserted, the enzyme is not produced, and colonies remain white (recombinant).