Q. 9 - Biology

Question

The ara operon is an inducible operon that controls the production of the sugar arabinose. When arabinose is present in a bacterium it binds to the protein AraC, and the complex binds to the initiator site to promote transcription. In this scenario, AraC is a(n) ________. a. activator b. inducer c. repressor d. operator

Step-by-Step Solution

Answer

Option a is correct.

Step 1. Introduction

An operon is a set of many structural genes that are positioned under a common promotor and regulated by a common operator. For example lac operon where Lac refers to lactose.

Step 2. Explanation of the correct option

Option a is correct because the Inducible operon is one whose expression increases in response to the inducer, enhancer, or positive indicator. Activators are the transcriptional factor that increases the transcription of the gene. In the Ara operon, AraC is a protein that recruits other coactivators and results in gene activation, hence in this scenario AraC is an activator.

Step 3. Explanation of the incorrect options

Option b is incorrect because inducers control the transcription either by inactivating repressors or by activating activator proteins.

Option c is incorrect because repressors recruit corepressors and lead to transcriptional repression.

Option d is incorrect because the operator is a gene in which the repressor binds.