DNA is a double-stranded molecule. One of the two strands of DNA is an original strand also while the other is the newly-synthesized strand.

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Due to the fact that one of the 2 strands of DNA is always conoffered, DNA replication is considered as a semiconservative procedure.

DNA replication is the process of manufacturing new DNA. It synthesizes a brand-new DNA strand also by adding complementary nucleotides to the theme strand. DNA polymerase is the enzyme responsible for the synthesis of new DNA strand also.

Key Areas Covered

1. What is DNA Replication – Definition, Steps, Function 2. Why is DNA Replication Described as Semiconservative – Synthesis of a New DNA Strand

Key Terms: DNA Replication, Elongation, Initiation, Lagging Strand, Leading Strand also, Original Strand, Termination


What is DNA Replication

DNA replication is the cellular process whereby a precise replica of a certain DNA molecule is developed using the original DNA strands as templates. The three actions of DNA replication are initiation, elongation, and termination. The initiation of DNA replication occurs at the origin of replication of the chromosome. Once DNA polymerase binds to the beginning of replication, it starts adding nucleotides to the 3′ end of the RNA primer. RNA primer is synthesized by RNA primase. The growth/elongation of the new DNA strand also occurs in the 3′ to 5′ direction. Both strands of DNA serve as templates. The unwound DNA strands develop a replication fork. DNA replication at the replication fork is shown in figure 1.


Figure 1: DNA Replication

The main attribute of DNA polymerase in DNA replication is to include complementary nucleotides to the thriving chain. Sugar-phosphate backbone is formed by the phosphodiester bond development between the proximal phosphate group and also the 3′ OH of the pentose ring of incoming nucleotide. The termination of DNA replication occurs in the telomeric areas of the chromosome.

Why is DNA Replication Described as Semiconservative

Due to the fact that DNA is a double-stranded molecule, both strands serve as templates in DNA replication. Hence, DNA replication occurs bi-directionally at the replication fork. However before, one design template strand runs in the 5′ to 3′ direction while the various other template strand also runs in the 3′ to 5′ direction. The strand via 5′ to 3′ directionality is referred to as the leading strand as a consistent DNA replication occurs on that strand. The other strand also with 3′ to 5′ directionality is referred to as the lagging strand also. It is synthesized as pieces called Okazaki fragments. Bi-directional DNA replication is presented in figure 2.


Figure 2: Bi-Directional DNA Replication

As both strands serve as templates in DNA replication, a certain double-stranded DNA is composed of an old strand and a freshly synthesized strand also. The old strand serves as the layout for replication, creating the brand-new strand also, which is complementary to the layout strand. Therefore, each DNA molecule is written of an original DNA strand together with a newly synthesized DNA strand also. Due to the fact that among the two strands of DNA is not readjusted or conoffered, DNA replication is considered as a semiconservative procedure. Semiconservative DNA replication is shown in figure 3.


Figure 3: Semiconservative DNA Replication

The semiconservative DNA replication permits DNA repair mechanisms to work on the newly-synthesized DNA strand also.


DNA replication is a semiconservative procedure as one of the 2 strands of the double-stranded DNA is an original DNA strand also, which offered as the theme for the synthesis of the brand-new strand. Because one of the two strands is always conserved, DNA replication is thought about as a semiconservative process.

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1. “Semi-Conservative DNA Replication: Meselson and Stahl.” Nature News, Nature Publishing Group, Available right here.

Image Courtesy:

1. “DNA Replication” (Publci Domain) using Public Domain Files 2. “DNA replication split” By I, Madprime (CC BY-SA 3.0) through Commons Wikimedia 3. “Semiconservative replication” By Lizanne Koch – lgkoch – own occupational through chemdraw (Public Domain) using Commons Wikimedia