Table of contents

1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

10. Transcription

Transcription in Prokaryotes

Genetics

10. Transcription

Transcription in Prokaryotes

Previous problemNext problem

2:32 minutes

Problem 20c

Textbook Question

Wild-type E. coli grows best at 37°C but can grow efficiently up to 42°C. An E. coli strain has a mutation of the sigma subunit that results in an RNA polymerase holoenzyme that is stable and transcribes at wild-type levels at 37°C. The mutant holoenzyme is progressively destabilized as the temperature is raised, and it completely denatures and ceases to carry out transcription at 42°C. Relative to wild-type growth, characterize the ability of the mutant strain to carry out transcription at 42°C

Verified step by step guidance

Understand the role of the sigma subunit in RNA polymerase: The sigma subunit is a critical component of the RNA polymerase holoenzyme in prokaryotes. It is responsible for recognizing promoter sequences and initiating transcription. A mutation in the sigma subunit can affect the stability and functionality of the holoenzyme.

Analyze the given information about the mutant strain: The mutant RNA polymerase holoenzyme is stable and transcribes at wild-type levels at 37°C. However, as the temperature increases, the mutant holoenzyme becomes progressively destabilized, and at 42°C, it completely denatures and ceases transcription.

Compare the mutant strain to the wild-type strain: Wild-type E. coli can grow efficiently at temperatures up to 42°C, which implies that its RNA polymerase holoenzyme remains stable and functional at this temperature. In contrast, the mutant strain's holoenzyme is unable to maintain stability and function at 42°C.

Characterize the transcriptional ability of the mutant strain at 42°C: Since the mutant holoenzyme completely denatures at 42°C, the mutant strain will be unable to carry out transcription at this temperature. This inability to transcribe genes will prevent the mutant strain from synthesizing essential proteins, ultimately inhibiting its growth.

Conclude the relative ability of the mutant strain: Relative to the wild-type strain, the mutant strain is transcriptionally deficient at 42°C due to the instability of its RNA polymerase holoenzyme. This deficiency highlights the importance of the sigma subunit's stability in maintaining transcriptional activity under elevated temperatures.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

RNA Polymerase Function

RNA polymerase is an essential enzyme responsible for synthesizing RNA from a DNA template during transcription. It forms a holoenzyme complex that includes a sigma factor, which helps the enzyme recognize specific promoter regions on the DNA. Understanding how mutations in the sigma subunit affect the stability and function of RNA polymerase is crucial for analyzing the transcription capabilities of the E. coli strain at different temperatures.

Temperature Effects on Enzyme Activity

Enzymes, including RNA polymerase, are sensitive to temperature changes, which can affect their stability and activity. Generally, an increase in temperature can enhance enzyme activity up to a certain point, beyond which the enzyme may denature and lose function. In the context of the mutant E. coli strain, recognizing how temperature impacts the stability of the RNA polymerase holoenzyme is vital for understanding its transcriptional capabilities at 42°C.

Mutations and Phenotypic Expression

Mutations are changes in the DNA sequence that can lead to alterations in protein structure and function. In this case, the mutation in the sigma subunit of E. coli affects the stability of the RNA polymerase holoenzyme, which in turn influences the organism's ability to transcribe RNA at elevated temperatures. Analyzing how this mutation impacts the phenotype, particularly at 42°C, is essential for characterizing the growth and transcription efficiency of the mutant strain.

Watch next

Master Prokaryotic Transcription with a bite sized video explanation from Kylia

Start learning

Related Videos

Related Practice

Textbook Question

The segment of the bacterial TrpA gene involved in intrinsic termination of transcription is the following:

3'-TGGGTCGGGGCGGATTACTGCCCCGAAAAAAAACTTG-5'

5'-ACCCAGCCCCGCCTAATGACGGGGCTTTTTTTTGAAC-3' Draw the mRNA structure that forms during transcription of this segment of the TrpA gene.

467

views

Textbook Question

The segment of the bacterial TrpA gene involved in intrinsic termination of transcription is the following:

3'-TGGGTCGGGGCGGATTACTGCCCCGAAAAAAAACTTG-5'

5'-ACCCAGCCCCGCCTAATGACGGGGCTTTTTTTTGAAC-3'

Explain how a sequence of this type leads to intrinsic termination of transcription.

466

views

Textbook Question

Describe the structure of RNA polymerase in bacteria. What is the core enzyme? What is the role of the σ subunit?

781

views

Textbook Question

Wild-type E. coli grows best at 37°C but can grow efficiently up to 42°C. An E. coli strain has a mutation of the sigma subunit that results in an RNA polymerase holoenzyme that is stable and transcribes at wild-type levels at 37°C. The mutant holoenzyme is progressively destabilized as the temperature is raised, and it completely denatures and ceases to carry out transcription at 42°C. Relative to wild-type growth, characterize the ability of the mutant strain to carry out transcription at What term best characterizes the type of mutation exhibited by the mutant bacterial strain? (Hint: The term was used in Chapter 4 to describe the Himalayan allele of the mammalian C gene.)

526

views

Textbook Question

Wild-type E. coli grows best at 37°C but can grow efficiently up to 42°C. An E. coli strain has a mutation of the sigma subunit that results in an RNA polymerase holoenzyme that is stable and transcribes at wild-type levels at 37°C. The mutant holoenzyme is progressively destabilized as the temperature is raised, and it completely denatures and ceases to carry out transcription at 42°C. Relative to wild-type growth, characterize the ability of the mutant strain to carry out transcription at 40°C

764

views

Textbook Question

Wild-type E. coli grow best at 37°C but can grow efficiently up to 42°C. An E. coli strain has a mutation of the sigma subunit that results in an RNA polymerase holoenzyme that is stable and transcribes at wild-type levels at 37°C. The mutant holoenzyme is progressively destabilized as the temperature is raised, and it completely denatures and ceases to carry out transcription at 42°C. Relative to wild-type growth, characterize the ability of the mutant strain to carry out transcription at 37°C

428

views

Textbook Question

Write a paragraph describing the abbreviated chemical reactions that summarize RNA polymerase-directed transcription.

481

views

Textbook Question

A mutant strain of Salmonella bacteria carries a mutation of the rho protein that has full activity at 37°C but is completely inactivated when the mutant strain is grown at 40°C. Are all mRNAs affected by the rho protein mutation in the same way? Why or why not?

436

views

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap