Study Guide for Campbell Biology
Study Guide for Campbell Biology
11th Edition
ISBN: 9780134443775
Author: Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Jane B. Reece, Martha R. Taylor, Michael A. Pollock
Publisher: PEARSON
bartleby

Concept explainers

bartleby

Videos

Textbook Question
Chapter 18, Problem 1IQ

In the following diagram of the lac operon, an inducible operon, identify components a through i.

Chapter 18, Problem 1IQ, In the following diagram of the lac operon, an inducible operon, identify components a through i.

Expert Solution & Answer
Check Mark
Summary Introduction

To identify: The components of an inducible operon, the lac operon.

Introduction: An operon is the functioning part of deoxyribonucleic acid (DNA). Each operon consists of a cluster of functionally related genes that share a single promoter and controlled by a shared operator. Lac operon is an inducible operon that controls the lactose metabolism in Escherichia coli and many other enteric bacteria.

Answer to Problem 1IQ

Pictorial representation: The components of lac operon are labeled in Fig.1.

Study Guide for Campbell Biology, Chapter 18, Problem 1IQ

Fig.1: Lac operon

Explanation of Solution

Lac operon is a group of genes with a single promoter. The genes in the lac operon encode proteins that allow a transport and metabolism of lactose in Escherichia coli.

  1. Regulatory gene (lacI): Regulatory gene controls the expression of other genes. The lac regulatory gene (lacI) codes for a repressor protein that can bind to the operator of the lac operon.
  2. Promoter: Promoter is the region adjacent to the operator in the lac operon, where the RNA polymerase binds to initiate a transcription of lactose genes. Promoter region switches on or off the gene expression through protein binding.
  3. Operator: Operator is the region that lies partially within the promoter in the lac operon. Operator region interacts with the regulatory protein that controls the transcription of the operon.
  4. Genes coding for enzymes: The lac operon consists of three genes such as lacZ, lacY, and lacA. lacZ gene transcribes as a single mRNA sequence. The lacZ gene encodes an enzyme β-galactosidase, lacY gene encodes an enzyme permease, and the lacA gene encodes trans-acetylase enzyme.
  5. Operon: Operon is the functional part of a DNA that consists of a group of functionally related genes regulated by a shared operator.
  6. RNA polymerase: RNA polymerase is an enzyme that synthesizes RNA and catalyzes the initiation and elongation of RNA using a process called transcription. In lac operon, RNA polymerase binds to the promoter region to initiate transcription.
  7. Active repressor: The activity of repressor (allosteric protein) may be determined by the presence or absence of the co-repressor. The repressor protein is produced by the regulatory gene and is activated by the association of a co-repressor. The activated repressor binds to the operator region, and it inhibits the transcription of lac operon genes.
  8. Inducer (allolactose): Inducer is allolactose, an isomer of lactose, which triggers or induces transcription. The inducer binds to and inactivates the repressor protein to induce the transcription of operon.
  9. mRNA for enzymes for lactose utilization: The genes of lac operon transcribe a single mRNA that encodes enzymes. The lacZ gene encodes an enzyme β-galactosidase, lacY gene encodes an enzyme permease, and the lacA gene encodes trans-acetylase enzyme for lactose utilization in Escherichia coli.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!
Students have asked these similar questions
In the lac operon system, do the inducers act at the transcription or translation level? Explain why it acts in that level in a short but concise way.
Which of the following lac operon genotypes would allow for functional versions of all the structural enzymes of the lac operon to be expressed constitutively even in the absence of lactose?   Group of answer choices I+ O+ Z+ Y+ A+ I- O+ Z- Y- A- I+ OC Z+ Y+ A+ IS O+ Z+ Y+ A+ I+ O+ Z- Y+ A+
In terms of the trp operon, differentiate between two normal bacterial cultures, one grown in a medium supplied with tryptophan and the other medium without tryptophan.
Knowledge Booster
Biology
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.
Similar questions
    • SEE MORE QUESTIONS
    Recommended textbooks for you
  • Biology (MindTap Course List)
    Biology
    ISBN:9781337392938
    Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg
    Publisher:Cengage Learning
  • Biology (MindTap Course List)
    Biology
    ISBN:9781337392938
    Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg
    Publisher:Cengage Learning
    Bacterial Genomics and Metagenomics; Author: Quadram Institute;https://www.youtube.com/watch?v=_6IdVTAFXoU;License: Standard youtube license