Question

Describe how recombinant DNA techniques can be used to express a mammalian gene in bacteria.

a) By inserting the mammalian gene into a bacterial plasmid and using a restriction enzyme to cut the DNA.
b) By using ligase to join the mammalian gene with bacterial DNA, creating a recombinant DNA molecule.
c) By incorporating the recombinant DNA into the bacterial cell, allowing it to produce the mammalian protein.
d) By utilizing promoters to initiate transcription of the mammalian gene within the bacterial host.

Answer 1

Recombinant DNA techniques involve cutting and isolating a mammalian gene using restriction enzymes, ligating it into a bacterial plasmid, transforming bacteria with the recombinant plasmid, and using bacterial promoters to express the gene.

Step-by-step explanation:

To express a mammalian gene in bacteria using recombinant DNA techniques, several steps are involved:

1. Isolation and cutting of the mammalian gene using a restriction enzyme that targets a specific sequence, allowing isolation of the desired gene.
2. Ligation of the isolated gene into a plasmid using DNA ligase, forming a recombinant DNA molecule. The plasmid serves as a cloning vector and contains features that facilitate the insertion, removal, and expression of the desired gene.
3. Introducing the recombinant plasmid into bacterial cells through a process called transformation, enabling the bacteria to take up and replicate the recombinant DNA within their own cellular machinery.
4. Using promoters specific to bacterial expression systems to initiate the transcription of the mammalian gene, leading to the production of the mammalian protein within the bacterial host.

Through these steps, bacteria become capable of producing the mammalian protein, which can then be collected and used for various applications, such as medical research or the production of pharmaceuticals.

A promoter is a critical element within the cloning vector, which provides the necessary signal for the expression of the inserted gene within the bacterial cell. Without an appropriate promoter that functions in the bacterial host, the gene of interest will not be transcribed into mRNA and subsequently translated into protein.