Question

40. Which one of the following bacterium is considered as 'natural genetic engineer'?
(A) Agrobacterium tumefaciens
(B) Agrobacterium radiobactor
(C) Pseudomonas putida
(D) Thermus aquaticus​

Answer 1

Answer:

Many of the genetic engineering works involve the transfer of genes, i. e. transfer of DNA from one organism to the other. For that purpose, desired DNA is inserted into a vector and is transferred into the competent cell in a process known as transformation. All these steps are carried out in laboratories to engineer the desired organism genetically. The entire process of transformation is performed by scientists, known as genetic engineers.

On the other hand, the bacterium Agrobacterium tumefaciens contains inside its cell, a plasmid, i. e. an extrachromosomal self-replicating small DNA, known as Ti plasmid (tumour inducing plasmid) that induce overproduction of growth factors in the host cells eventually leading to cell proliferation & tumour formation. This bacterium establishes contact with suitable root cells of plants by recognising chemical signals and then prepares its plasmid ready to be delivered through t-pilus developed by type IV secretion system . Then it transfers this DNA (also known as t-DNA) into the plant host cell. This delivery requires the assistance of several viral proteins. The t-DNA is transferred and stably integrated into the host chromosome which laterwards leads in tumour development in the host. The whole process of successful DNA transfer and integration is performed & monitored by the bacteria itself (which in vivo is done by genetic engineers in laboratories ).

Explanation:

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Answer 2

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