In the absence of lactose, the repressor protein encoded by the I gene binds to the lac operator and prevents transcription. Binding of allolactose to the repressor causes it to leave the operator. This enables RNA polymerase to transcribe the three genes of the operon.
A tough-skinned tropical fruit, the mango features a sweet, orange- to red-color flesh inside when ripe. Kensington pride, Kent, Palmer and sensation are only a few of the many varieties of mango available through groceries and markets.
If a mango feels soft inside, it is ripe and ready to be eaten. If a mango is rock-hard, leave it on the counter. The good news is that mangoes ripen on the counter in a few days. Just leave an upripe mango on the counter and check it after 2 days.