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Related Concept Videos

DNA Topoisomerases02:02

DNA Topoisomerases

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Topoisomerases are enzymes that relax overwound DNA molecules during various cell processes, including DNA replication and transcription. These enzymes regulate positive and negative DNA supercoiling without changing the nucleotide sequence. DNA overwinding in a clockwise direction results in positively supercoiled DNA, whereas underwinding in a counterclockwise direction produces negatively supercoiled DNA.
Types and Mechanism of action
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DNA as a Genetic Template02:05

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Two structural features of the DNA molecule provide a basis for the mechanisms of heredity: the four nucleotide bases and its double-stranded nature. The Watson-Crick model of double-helical DNA structure, proposed in 1952, drew heavily upon the X-ray crystallography work of researchers Rosalind Franklin and Maurice Wilkins. Watson, Crick, and Wilkins jointly received the Nobel Prize in Physiology or Medicine for their work in 1962. Franklin was, controversially, excluded from the prize for...
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Replication in Prokaryotes01:32

Replication in Prokaryotes

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DNA replication has three main steps: initiation, elongation, and termination. Replication in prokaryotes begins when initiator proteins bind to the single origin of replication (ori) on the cell's circular chromosome. Replication then proceeds around the entire circle of the chromosome in each direction from the two replication forks, resulting in two DNA molecules.
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Overview
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Genomic DNA in Prokaryotes00:46

Genomic DNA in Prokaryotes

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The genome of most prokaryotic organisms consists of double-stranded DNA organized into one circular chromosome in a region of cytoplasm called the nucleoid. The chromosome is tightly wound, or supercoiled, for efficient storage. Prokaryotes also contain other circular pieces of DNA called plasmids. These plasmids are smaller than the chromosome and often carry genes that confer adaptive functions, such as antibiotic resistance.
Genomic Diversity in Bacteria
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DNA Bacteriophages01:26

DNA Bacteriophages

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Bacteriophages, or phages, are viruses that specifically infect bacteria, utilizing their genetic material to hijack host cellular machinery for replication. DNA bacteriophages employ single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA) genomes. These phages exhibit diverse replication strategies and host interactions, influencing their ecological roles and applications in biotechnology and medicine.ssDNA BacteriophagesssDNA phages, with their small genomes, utilize unique strategies to...
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Tools to Study the Role of Architectural Protein HMGB1 in the Processing of Helix Distorting, Site-specific DNA Interstrand Crosslinks
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DNA Supercoiling Measurement in Bacteria.

Yingting Liu1,2,3, Zhi-Chun Hua3,4, Fenfei Leng5,6

  • 1Biomolecular Sciences Institute, Florida International University, Miami, FL, 33199, USA.

Methods in Molecular Biology (Clifton, N.J.)
|November 28, 2017
PubMed
Summary

This study details how to isolate plasmid DNA from E. coli and measure its supercoiling density using agarose gel electrophoresis and chloroquine. This method helps understand DNA supercoiling, crucial for bacterial DNA replication and transcription.

Keywords:
Agarose gel electrophoresisDNA supercoilingDNA topoisomersSupercoiling density

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Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • DNA supercoiling is vital for DNA replication, transcription, and recombination.
  • Plasmid DNA is commonly used to assess bacterial DNA supercoiling levels.

Purpose of the Study:

  • To describe a method for isolating plasmid DNA from E. coli.
  • To determine DNA supercoiling density using agarose gel electrophoresis with chloroquine.

Main Methods:

  • Isolation of plasmid DNA from E. coli.
  • Agarose gel electrophoresis (1%) with chloroquine to analyze supercoiling.
  • Utilizing plasmid pACYC184 as a model system.

Main Results:

  • Successfully isolated plasmid DNA from E. coli.
  • Demonstrated the ability to determine DNA supercoiling density via gel electrophoresis.
  • Visualized changes in DNA supercoiling based on electrophoresis results.

Conclusions:

  • The described method provides a reliable way to measure DNA supercoiling density in bacteria.
  • Understanding DNA supercoiling is essential for comprehending fundamental DNA metabolic processes.