Genetic Engineering (Class XII)

It contains the palindrome for EcoRI-GAATTC.

Cutting both the target gene and the carrier plasmid will create complementary sticky ends required for fitting the target gene into the carrier plasmid.

Agrobacterium tumefasciens has a tumor-inducing plasmid, which has a specific region called T-DNA. This T-DNA gets integrated in the plant genome. Since it happens as a natural phenomenon, the bacterium is called a natural genetic engineer.

Denaturation or separation of DNA strands is the first step. This step separates the strands by heating to a high temperature. Each separate strand can then serve as a template for copying.

Acidic nature of DNA does not form the basis of polymearse chain reaction.

Reverse transcriptase transcribes RNA into DNA.

DNA ligase joins the complementary sticky ends together.

To know which host cells have taken up the recombined DNA, a radioactive nucleic acid probe, complementary to the gene of interest is added to the growth media. It enters the cells and if a cell contains the gene of interest, it binds to that region of DNA. The colony that emits radioactivity indicates the presence of the gene.

It is a technique for the identification of an organism by matching the DNA restriction fragment lengths by using the technique RFLP. Same DNA will generate same DNA lengths when treated with a fixed set of restriction enzymes.

Bacteria are used as host cells, not as vectors. They are large in size and contain a single circular chromosome. However, it provides an ideal environment for cloning of rDNA irrespective of vectors which may be a bacteriophage, plasmid, YAC or BAC.

A palindrome is a region on a double stranded DNA where the 5' to 3' sequence on one strand matches the 5' to 3' on the complementary strand. Such sites are cleaving sites for specific restriction enzymes.

Bacteria multiply at astounding rates. E. coli forms visible colonies within 24 hours. Hence, it is quick and easy to deal with.

The lacZ gene containing restriction sites is used as a marker gene. The target DNA is inserted in between this gene. In a recombined vector, insertion inactivates lacZ gene, so the enzyme beta galactosidase will not be produced and hence, X-gal will not be converted to the blue insoluble product. So, a blue colony indicates that insertion has not taken place and hence, the enzyme beta galactosidase is produced. It indicates the presence of non-recombined vector.

It’s the most appropriate choice. Its restriction site is present inside a marker gene and hence, the researcher will be able to screen for recombinants later.

The speed of fragments depends on their charge to mass ratio in the electric field. Smaller (hence, lighter) fragments move faster compared to longer (hence, heavier) fragments.