DNA replication

(noun)

a biological process occuring in all living organisms that is the basis for biological inheritance

Related Terms

Examples of DNA replication in the following topics:

  • DNA Replication in Prokaryotes

    • Prokaryotic DNA is replicated by DNA polymerase III in the 5' to 3' direction at a rate of 1000 nucleotides per second.
    • As the DNA opens up, Y-shaped structures called replication forks are formed.
    • A replication fork is formed when helicase separates the DNA strands at the origin of replication.
    • The DNA tends to become more highly coiled ahead of the replication fork.
    • Explain the functions of the enzymes involved in prokaryotic DNA replication

  • Chromosomes and DNA Replication in the Archaea

    • The circular chromosomes contain multiple origins of replication, using DNA polymerases that resemble eukaryotic enzymes.
    • DNA replication, similar in all systems, involves initiation, elongation, and termination.
    • The replication of DNA, beginning at the origins of replication present on the circular chromosomes, requires initiator proteins.
    • The DNA replication system in Archaea, similar to all systems, requires a free 3'OH group before synthesis is initiated.
    • Once the RNA primase has performed its job, DNA synthesis continues in a similar fashion by which the eukaryotic system and the DNA is replicated.

  • Inhibiting Nucleic Acid Synthesis

    • Other antimicrobial drugs interfere with DNA replication, the biological process that occurs in all living organisms and copies their DNA and is the basis for biological inheritance.
    • In a cell, DNA replication begins at specific locations in the genome, called "origins. " Uncoiling of DNA at the origin, and synthesis of new strands, forms a replication fork.
    • DNA replication, like all biological polymerization processes, proceeds in three enzymatically catalyzed and coordinated steps: initiation, elongation and termination.
    • Any of the steps in the process of DNA replication can be targeted by antimicrobial drugs.
    • For instance, quinolones inhibit DNA synthesis by interfering with the coiling of DNA strands.

  • Basics of DNA Replication

    • DNA replication uses a semi-conservative method that results in a double-stranded DNA with one parental strand and a new daughter strand.
    • Watson and Crick's discovery that DNA was a two-stranded double helix provided a hint as to how DNA is replicated.
    • In dispersive replication, after replication both copies of the new DNAs would somehow have alternating segments of parental DNA and newly-synthesized DNA on each of their two strands.
    • Meselson and Stahl were interested in understanding how DNA replicates.
    • The three suggested models of DNA replication.

  • DNA Replication in Eukaryotes

    • As the DNA opens up, Y-shaped structures called replication forks are formed.
    • Once DNA replication is finished, the daughter molecules are made entirely of continuous DNA nucleotides, with no RNA portions.
    • Each origin of replication forms a bubble of duplicated DNA on either side of the origin of replication.
    • DNA polymerase halts when it reaches a section of DNA template that has already been replicated.
    • A replication fork is formed by the opening of the origin of replication; helicase separates the DNA strands.

  • Telomere Replication

    • As DNA polymerase alone cannot replicate the ends of chromosomes, telomerase aids in their replication and prevents chromosome degradation.
    • After DNA replication, each newly synthesized DNA strand is shorter at its 5' end than at the parental DNA strand's 5' end.
    • These telomeres protect the important genes from being deleted as cells divide and as DNA strands shorten during replication.
    • After sufficient rounds of replication, all the telomeric repeats are lost, and the DNA risks losing coding sequences with subsequent rounds.
    • A simplified schematic of DNA replication where the parental DNA (top) is replicated from three origins of replication, yielding three replication bubbles (middle) before giving rise to two daughter DNAs (bottom).

  • DNA Repair

    • Most mistakes during replication are corrected by DNA polymerase during replication or by post-replication repair mechanisms.
    • DNA replication is a highly accurate process, but mistakes can occasionally occur as when a DNA polymerase inserts a wrong base.
    • Most of the mistakes during DNA replication are promptly corrected by DNA polymerase which proofreads the base that has just been added .
    • Errors during DNA replication are not the only reason why mutations arise in DNA.
    • DNA ligases catalyse the crucial step of joining breaks in duplex DNA during DNA repair, replication and recombination, and require either Adenosine triphosphate (ATP) or Nicotinamide adenine dinucleotide (NAD+) as a cofactor.

  • Selection

    • Molecular cloning generally uses DNA sequences from two different organisms: the species that is the source of the DNA to be cloned, and the species that will serve as the living host for replication of the recombinant DNA.
    • This will generate a population of organisms in which recombinant DNA molecules are replicated along with the host DNA.
    • Therefore, if any segment of DNA from any organism is inserted into a DNA segment containing the molecular sequences required for DNA replication, and the resulting recombinant DNA is introduced into the organism from which the replication sequences were obtained, then the foreign DNA will be replicated along with the host cell's DNA in the transgenic organism.
    • Molecular cloning is similar to polymerase chain reaction (PCR) in that it permits the replication of a specific DNA sequence.
    • The fundamental difference between the two methods is that molecular cloning involves replication of the DNA in a living microorganism, while PCR replicates DNA in an in vitro solution, free of living cells.

  • Replication of Double-Stranded DNA Viruses of Animals

    • Double-stranded DNA viruses usually must enter the host nucleus before they are able to replicate.
    • Polyomaviruses, adenoviruses, and herpesviruses are all nuclear-replicating DNA viruses, each with their own specific approaches to replication.
    • Adenoviruses possess a linear dsDNA genome and are able to replicate in the nucleus of vertebrate cells using the host’s replication machinery.
    • Within the nucleus, replication of viral DNA and transcription of viral genes occurs.
    • The replication of poxvirus is unusual for a virus with double-stranded DNA genome (dsDNA) because it occurs in the cytoplasm, although this is typical of other large DNA viruses.

  • Viral Identification

    • DNA viruses: The genome replication of most DNA viruses takes place in the cell's nucleus.
    • RNA viruses: Replication usually takes place in the cytoplasm.
    • Reverse transcribing viruses with RNA genomes (retroviruses), use a DNA intermediate to replicate, whereas those with DNA genomes (pararetroviruses) use an RNA intermediate during genome replication.
    • Retroviruses integrate the DNA produced by reverse transcription into the host genome as a provirus as a part of the replication process.
    • An example of Baltimore Virus classification I: dsDNA virusesII: ssDNA virusesIII: dsRNA virusesIV: (+)ssRNA virusesV: (−)ssRNA virusesVI: ssRNA-RT virusesVII: dsDNA-RT viruses