Lecture 13_250 review - Tagged

Exam 2 Review Topics: Molecular Regulation

Key Concepts and Definitions

• Operator

  • A segment of DNA where a transcription factor or repressor can bind to regulate gene expression.

• Constitutive Expression

  • Refers to genes that are continuously expressed without regulation, often vital for basic cellular function.

• Induced Expression

  • A form of regulation where gene expression is activated in response to specific signals or conditions.

Types of Induced Expressions

Repressible Operon

• Role of Repressors and Co-repressors

  • Repressors inhibit transcription by binding to the operator. Co-repressors activate repressors and assist in gene regulation.

• Define Derepression

  • The process by which gene transcription is activated following the removal of a repressor or co-repressor.

Inducible Operon

• Role of Repressors and Inducers

  • Repressors prevent gene expression; inducers deactivate the repressor allowing transcription to occur.

• Role of Activators and Inducers

  • Activators enhance transcription efficiency and work alongside inducers to promote gene expression.

Case Study: Hawaiian Bobtailed Squid and Vibrio fischeri Symbiosis

• Role of Molecular Regulation in Symbiosis

  • Molecular regulation governs the interaction and mutual benefits between the squid and bacteria, guiding their development and behavior.

• LuxR Protein Role

  • A transcriptional activator in the Lux operon that mediates responses to the autoinducer produced by Vibrio fischeri, contributing to bioluminescence regulation.

• Autoinducer Role

  • A signaling molecule produced by bacteria that initiates group behaviors like bioluminescence when reaching a threshold concentration, facilitating communication between bacteria.

• What Type of Operon is Lux Operon?

  • The Lux operon is an inducible operon, which is activated in response to the presence of an autoinducer.