Question

the lac operon - when ____ is __ present, the __ __ are turned off by regulatory proteins that bind to dna and __ transcription. promoters and operators - located in front of the operon’s three genes are two regulatory regions: - a __ - an __ the lac repressor blocks transcription - when the lac repressor binds to the __ __, rna __ cannot reach the lac genes to begin __ laclose turns on the operon - when __ is added to the __, it __ into the cell and attaches to the __ __ eukaryotic gene regulation - a typical eukaryotic gene has a __ ____

Explanation:

These fill-in-the-blank questions cover prokaryotic (lac operon) and eukaryotic gene regulation concepts from molecular biology.

1. For the lac operon default state: When glucose is present, the lac operon genes are repressed by regulatory proteins that block transcription.
2. The two regulatory regions before lac operon genes are a promoter and an operator.
3. The lac repressor binds the operator region, preventing RNA polymerase from accessing lac genes to start transcription.
4. Lactose triggers operon activation: added to the growth medium, it enters the cell and binds the lac repressor.
5. A typical eukaryotic gene has a TATA box as a key regulatory sequence.

Answer:

The Lac Operon

• When glucose is present, the lac operon genes are turned off by regulatory proteins that bind to DNA and block transcription.

Promoters and Operators

• Located in front of the operon's three genes are two regulatory regions:
• A promoter
• An operator

The Lac Repressor Blocks Transcription

• When the lac repressor binds to the operator region, RNA polymerase cannot reach the lac genes to begin transcription

Lactose Turns On the Operon

• When lactose is added to the growth medium, it diffuses into the cell and attaches to the lac repressor

Eukaryotic Gene Regulation

• A typical eukaryotic gene has a TATA box