In this problem you will explore how to solve problems involving partial diploid

Question

In this problem you will explore how to solve problems involving partial diploid lac operon bacterial strains.

Bacterial strains that are "partially diploid" have two copies of the lac operon because they aquired a plasmid carrying just the lac operon region. One copy of the lac operon region is on the recipient's bacterial chromosome, and the other copy is on the F' plasmid that was introduced into the cell by conjugation. Partial diploid genotypes are written with the F' segment first and the recipient chromosome next.

You create a lac operon partial diploid with this genotype:

F' I+ P+ Oc Z+ Y? / I? P+ O+ Z? Y+

To determine which genes are transcribed and under what conditions, you need to first consider each genotype separately, and then together.

Explanation / Answer

F' I+ P+ Oc Z+ Y: Promoter sequence is functional, repressor is produced, Operator sequence is functional, Beta - galactosidase is produced from lacZ gene, permease gene is not produced from lac Y gene.

I P+ O+ Z Y+: Repressor is not produced, promoter sequence is functional, operator is functional, Beta - galactosidase is not produced from lacZ gene, permease gene is produced from lac Y gene.

F' I+ P+ Oc Z+ Y / I P+ O+ Z Y+: Promoter sequence is functional, repressor is produced, Operator sequence is functional, Beta - galactosidase is produced from lacZ gene, permease gene is produced from lac Y gene.

Since, the genes that are turned off in one strain are converted to active genes when the plasmid is received by the recepient, all genes will become functional and are transcribed.

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