Becker's World of the Cell (9th Edition)
Becker's World of the Cell (9th Edition)
9th Edition
ISBN: 9780321934925
Author: Jeff Hardin, Gregory Paul Bertoni
Publisher: PEARSON
bartleby

Concept explainers

bartleby

Videos

Textbook Question
Book Icon
Chapter 20, Problem 20.1CC

Suppose you are analyzing a haploid E. coli strain and discover that the genes of the lac operon are never transcribed and that the bacteria cannot grow in lactose-containing medium. Provide two possible genotypes for your bacteria that would explain this phenotype.

Expert Solution & Answer
Check Mark
Summary Introduction

To determine: Two possible genotypes for a strain of haploid Escherichia coli bacteria in which the genes of the lac operon are never transcribed and the bacteria cannot grow in the lactose-containing medium.

Introduction: E. coli has a lactose operon, also called the lac operon. It is an inducible operon. This operon helps in the digestion and transportation of lactose. By genetic analysis of the lac operon of E. coli of various mutants, a lot of information has been retrieved.

Explanation of Solution

The lac operon under normal conditions can be represented by the genotype I+P+O+Z+ where the Z product will be expressed in the presence of lactose. The I gene represents the repressor gene, P represents the lac promoter gene, O represents the lac operator gene and the Z gene represents the protein product that is formed.

Two possible genotypes for a strain of haploid E. coli bacteria in which the genes of the lac operon are never transcribed and the bacteria cannot grow in the lactose-containing medium are as follows:

  • If the I gene has a mutation such that it shows the suppressor genotype, a repressor will be formed in every case. This repressor will bind to the operator in every case, that is whether a lactose inducer is present or absent. Thus, the transcription of the lac genes are suppressed and will never be transcribed. The genotype of such a strain of bacteria can be represented as IsP+O+Z+.
  • If the P gene has a mutation, the promoter will be non-functional. When the promoter is non-functional, the RNA polymerase enzyme will not be able to identify the promoter. Thus, the transcription of the lac genes are suppressed and will never be transcribed. The genotype of such a strain of bacteria can be represented as I+P-O+Z+.

Thus, two possible genotypes for a strain of haploid E. coli bacteria in which the genes of the lac operon are never transcribed and the bacteria cannot grow in the lactose-containing medium are IsP+O+Z+ and I+P-O+Z+.

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
what did charles darwin do in science
evolutionary analysis
Can I get this answered with the colors and what type of connection was formed? Hydrophobic, ionic, or hydrogen.
Knowledge Booster
Background pattern image
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
Text book image
Biology (MindTap Course List)
Biology
ISBN:9781337392938
Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg
Publisher:Cengage Learning
Text book image
Biology: The Dynamic Science (MindTap Course List)
Biology
ISBN:9781305389892
Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan
Publisher:Cengage Learning
Text book image
Biology Today and Tomorrow without Physiology (Mi...
Biology
ISBN:9781305117396
Author:Cecie Starr, Christine Evers, Lisa Starr
Publisher:Cengage Learning
Text book image
Human Heredity: Principles and Issues (MindTap Co...
Biology
ISBN:9781305251052
Author:Michael Cummings
Publisher:Cengage Learning
Text book image
Biochemistry
Biochemistry
ISBN:9781305577206
Author:Reginald H. Garrett, Charles M. Grisham
Publisher:Cengage Learning
Text book image
Biology 2e
Biology
ISBN:9781947172517
Author:Matthew Douglas, Jung Choi, Mary Ann Clark
Publisher:OpenStax
QCE Biology: Introduction to Gene Expression; Author: Atomi;https://www.youtube.com/watch?v=a7hydUtCIJk;License: Standard YouTube License, CC-BY