For the following lac operon partial diploids, determine whether the synthesis of lacZ mRNA is 'constitutive,' 'inducible,' or 'uninducible,' and indicate whether the partial diploid is  or  (able or not able to utilize lactose). 

Key Concepts

Lac Operon

The lac operon is a set of genes in E. coli that are involved in the metabolism of lactose. It consists of structural genes (lacZ, lacY, and lacA) and regulatory elements that control their expression. The operon is typically off when lactose is absent and can be turned on (induced) in the presence of lactose, allowing the bacteria to utilize this sugar as an energy source.

Constitutive, Inducible, and Uninducible Expression

Constitutive expression refers to genes that are continuously expressed regardless of environmental conditions. Inducible expression occurs when gene expression is turned on in response to specific stimuli, such as the presence of lactose for the lac operon. Uninducible expression means that the gene cannot be activated, even in the presence of the inducer, often due to mutations in regulatory elements.

Partial Diploids

Partial diploids are bacterial cells that contain two copies of some genes, typically due to the introduction of a plasmid or a second chromosome segment. In the context of the lac operon, analyzing partial diploids helps determine how mutations in one copy of the operon affect the expression of lacZ mRNA and the ability of the bacteria to utilize lactose, providing insights into gene regulation mechanisms.