Question

Now drag the lacZ gene to the appropriate location on the stretch of DNA. Wait a few seconds, then describe what happens.

a) DNA replication occurs
b) Transcription of lacZ gene
c) Translation of lacZ gene
d) LacZ gene is deleted

Answer 1

The lacZ gene, once inserted at an appropriate location in DNA, can lead to transcription and translation, resulting in the production of β-galactosidase needed for lactose metabolism. The insertion process involves cutting the DNA with restriction enzymes, inserting the foreign DNA, and using DNA ligase to join the strands, potentially disrupting the lacZ gene and preventing enzyme production.

Step-by-step explanation:

The lacZ gene is critical for the metabolism of lactose in bacteria. When the lacZ gene is inserted into the appropriate location of a DNA stretch within a plasmid, several processes can occur. By cutting the lacZ gene in the plasmid with the same restriction enzyme that cuts foreign DNA, we create a restriction site that will allow the foreign DNA to be inserted into the plasmid. This insertion disrupts the lacZ gene, preventing it from producing the enzyme β-galactosidase, which is necessary for metabolizing lactose.

After insertion of the foreign DNA into the lacZ gene, DNA ligase is used to repair the DNA by joining the 3'-OH ends of the transposon to the 5'-OH at the insertion site. Through a process involving DNA replication, the missing bases are replaced and replication occurs to generate direct repeats of host genomic DNA at the insertion site. A final ligation step completes the transposition, and the newly inserted lacZ gene can be transcribed, resulting in transcription of the lacZ gene. If the lacZ gene is functional and not disrupted by the insertion, it can then be translated to produce β-galactosidase. If the gene is disrupted, it won't produce functional enzyme.