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Related Concept Videos

Proofreading01:31

Proofreading

Synthesis of new DNA molecules is carried out by the enzyme DNA polymerase, which adds nucleotides on the daughter strand complementary to the template DNA strand. DNA polymerase has a higher affinity to add the correct base and ensures fidelity during DNA replication. Furthermore,  it exhibits proofreading activity during replication, using an exonuclease domain that cuts off incorrect nucleotides from the nascent DNA strand.
Errors During Replication are Corrected by the DNA Polymerase Enzyme
Proofreading01:43

Proofreading

Synthesis of new DNA molecules starts when DNA polymerase links nucleotides together in a sequence that is complementary to the template DNA strand. DNA polymerase has a higher affinity for the correct base to ensure fidelity in DNA replication. The DNA polymerase furthermore proofreads during replication, using an exonuclease domain that cuts off incorrect nucleotides from the nascent DNA strand.Errors during Replication Are Corrected by the DNA Polymerase EnzymeGenomic DNA is synthesized in...
Mutations in Microorganisms01:18

Mutations in Microorganisms

Mutations are heritable changes in an organism’s genome involving alterations in the base sequence of DNA or RNA. These changes can influence cellular processes and phenotypic traits, potentially transforming the unaltered wild type into a mutant form. Such changes, termed forward mutations, are pivotal in shaping the genetic diversity of organisms.RNA viruses exhibit the highest mutation rates due to the absence of robust proofreading mechanisms during genome replication. In contrast,...
Translesion DNA Polymerases02:10

Translesion DNA Polymerases

Translesion (TLS) polymerases rescue stalled DNA polymerases at sites of damaged bases by replacing the replicative polymerase and installing a nucleotide across the damaged site. Doing so, TLS allows additional time for the cell to repair the damage before resuming regular DNA replication.
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
Genome Copying Errors02:46

Genome Copying Errors

DNA replication is a well-evolved process that copies millions of base pairs with high fidelity during each cell division. Occasionally a wrong base or a long stretch of wrong bases may get added to the daughter strands. If the errors are left unchecked, cells might accumulate several mutations that might endanger their  survival. Therefore, the copying errors are checked and repaired at three levels.
Bacterial RNA Polymerase00:43

Bacterial RNA Polymerase

Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...

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Related Experiment Video

Updated: Jun 17, 2026

DNA Polymerase Activity Assay Using Near-infrared Fluorescent Labeled DNA Visualized by Acrylamide Gel Electrophoresis
07:38

DNA Polymerase Activity Assay Using Near-infrared Fluorescent Labeled DNA Visualized by Acrylamide Gel Electrophoresis

Published on: October 6, 2017

Optimization of DNA polymerase mutation rates during bacterial evolution.

Ern Loh1, Jesse J Salk, Lawrence A Loeb

  • 1Joseph Gottstein Memorial Cancer Research Laboratory, Department of Pathology, University of Washington, Seattle, WA 98195, USA.

Proceedings of the National Academy of Sciences of the United States of America
|January 19, 2010
PubMed
Summary

Higher mutation rates, specifically 10- to 47-fold above wild type, predominated in Escherichia coli evolution experiments. This suggests enhanced mutagenesis facilitates adaptation when organism fitness is not yet maximized.

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Mutagenesis and Functional Selection Protocols for Directed Evolution of Proteins in E. coli
09:01

Mutagenesis and Functional Selection Protocols for Directed Evolution of Proteins in E. coli

Published on: March 16, 2011

Related Experiment Videos

Last Updated: Jun 17, 2026

DNA Polymerase Activity Assay Using Near-infrared Fluorescent Labeled DNA Visualized by Acrylamide Gel Electrophoresis
07:38

DNA Polymerase Activity Assay Using Near-infrared Fluorescent Labeled DNA Visualized by Acrylamide Gel Electrophoresis

Published on: October 6, 2017

Mutagenesis and Functional Selection Protocols for Directed Evolution of Proteins in E. coli
09:01

Mutagenesis and Functional Selection Protocols for Directed Evolution of Proteins in E. coli

Published on: March 16, 2011

Area of Science:

  • Evolutionary biology
  • Microbial genetics

Background:

  • Mutation rate is a key factor in evolvability.
  • Previous studies primarily used pairwise comparisons to model optimal mutation rates.

Purpose of the Study:

  • To characterize the fitness landscape across a wide range of mutation rates.
  • To investigate the adaptive advantage of increased mutation rates in Escherichia coli.

Main Methods:

  • Generated 66 DNA polymerase I mutants in Escherichia coli with varying replication fidelities.
  • Competed strains for 350 generations in six replicate cultures across two environments.
  • Conducted pairwise competitions between mutator and wild-type strains.

Main Results:

  • A narrow range of mutation rates (10-47x wild type) predominated after serial passage.
  • Selected clones showed improved growth properties (doubling time, culture density).
  • Mutators were frequent winners, suggesting adaptation is driven by increased mutation probability.

Conclusions:

  • Enhanced mutagenesis facilitates adaptation when organism fitness is not maximized.
  • The competitive advantage of mutators stems from a higher probability of acquiring beneficial mutations.