Which sentence correctly describes inducers and co-repressors in gene regulation?

• A. Inducers bind to activators and inhibit gene expression, while co-repressors bind to activators and promote gene expression.
• B. Inducers bind to repressors and deactivate them, allowing gene expression, while co-repressors bind to repressors and activate them, inhibiting gene expression.
• C. Inducers and co-repressors both bind to DNA directly to regulate gene expression.
• D. Inducers activate repressors to block gene expression, while co-repressors deactivate repressors to allow gene expression.

Answer: (B)

Verified step by step guidance

1. Understand the role of repressors and activators in gene regulation: repressors typically bind to DNA to block transcription, while activators enhance transcription.
2. Recall that inducers are molecules that bind to repressors and cause them to release from the DNA, thereby allowing gene expression to proceed.
3. Recognize that co-repressors bind to repressors and enhance their ability to bind DNA, which inhibits gene expression.
4. Note that inducers do not bind to activators, and co-repressors do not promote gene expression; their effects are mediated through repressors.
5. Use this knowledge to evaluate the sentences and identify the one that correctly states that inducers deactivate repressors to allow gene expression, while co-repressors activate repressors to inhibit gene expression.