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.
Mango is a large, deep-rooted, symmetrical evergreen tree growing to 90 feet high and 80 feet wide. It has simple, alternate, lanceolate leaves 12 to 16 inches long that are yellow-green, purple, or copper colored when young, turning leathery, glossy, and deep green when mature.