We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is DNA Replication?

By Victoria Blackburn
Updated May 21, 2024
Our promise to you
All The Science is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At All The Science, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

The DNA molecule forms the basis of all known life because its structure enables it to be easily copied within living cells, allowing them to reproduce. An organism’s genetic information is contained within its DNA, and accurate duplication is required to pass on this information to subsequent generations. The copying of genetic material within the cell nucleus is called DNA replication. The mechanism by which it occurs is known as semi-conservative replication, and it involves the molecule splitting into two parts, each of which forms a template for a complete new molecule. Materials available within the cell are then added to these templates to complete the process.

The Structure of DNA

Each DNA molecule is made up of two strands, consisting of sugar and phosphate groups, with molecules known as bases forming links between them. There are four different bases: adenine (A), guanine (G), cytosine (C) and thymine (T). Each base, along with the sugar and phosphate groups to which it is attached, is known as a nucleotide. The two strands are held together by hydrogen bonds between the bases; A bonds with T and C with G, so that they form pairs known as complementary base pairs.

The strands form a double helix, or two parallel spiral structures, while the base pairs span the gap between the strands. The DNA molecules are normally tightly coiled, many times over, and form structures known as chromosomes. The complete genetic information, or genome for an organism is contained within a set of chromosomes; the human genome contains about three billion base pairs. DNA replication forms a new set of chromosomes, prior to cell division. The replication process can be broken down into a number of stages, each controlled by enzymes.


To replicate, the DNA strands must be separated. The hydrogen bonds between the base pairs are strong enough to hold the strands together under normal circumstances, but weak enough to allow them to be pulled apart easily when required. Since the molecule is normally in a highly coiled state, the two strands will not split without some help. Enzymes called gyrases work to relax, or uncoil, the DNA, while enzymes called helicases begin to unzip it, breaking the hydrogen bonds between the base pairs. Special proteins then bind to the separated strands in order to keep them apart and allow replication to occur.


Nucleotides exist independently of DNA in the nucleus of a cell or, in the case of bacteria, within the cell fluid. When a DNA molecule has been split, these free nucleotides bond with the unpaired complementary bases of each strand — A to T and C to G — forming a new, double-stranded molecule. This process is enabled by enzymes known as DNA polymerases. The two resulting copies each have one new strand and one from the original molecule. This is why DNA replication is called semi-conservative — half of each molecule is new and half is saved from its parent.

The processes of splitting and duplication overlap. As strands come apart, new complementary strands are built while the split continues along the double helix. DNA molecules in most organisms are very long, so it is more efficient for the splitting and duplication to occur in many places at once. These points are known as origins of replication. When two such origins meet, enzymes called ligases join the new strands together.

Error Checking

The replication process is extremely accurate, but errors do occur. Sometimes, a bond can form between the wrong combination of bases. For example, G can occasionally bond with T instead of A. The bases can also exist in slightly different forms that can bond in other, incorrect, pairings.

Typically, there is around one error for every 100 million base pair bonds. In a human, this would result in about 30 errors for each complete replication. There are, however, a number of error checking and correction mechanisms that detect and repair mistakes very effectively. For example, bonds between mismatched base pairs are relatively unstable, and the polymerase enzymes that assist the duplication process can also detach an incorrect nucleotide, allowing a new, correct, one to be added. These reduce the average number of errors per replication to about three.

Replication Errors: Mutations, Cancer, and Evolution

Errors in DNA replication are usually a bad thing at the individual level. They can lead to mutations, which are generally unfavorable; they may result in cancer or other life-threatening diseases. On the other hand, without these errors, human beings and other organisms as they are known today would not be here. Occasionally, a mutation can give an advantage, increasing an organism’s chances of surviving long enough to reproduce and pass on the favorable change, which will then become more common. This is how evolution works: replication errors allow organisms to adapt to changing environments and to evolve into new life forms.

All The Science is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

By anon257574 — On Mar 27, 2012

If I created from my cheek cells a double helix

on a glass side, will the double helix start dividing to new cells or not? --Richard I.

By anon100424 — On Jul 30, 2010

fantastic information pool. Great idea to have the information at the click of a button.

By anon99052 — On Jul 25, 2010

awesome collection of information about DNA. I have never seen such to the point information! Really!

All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.

All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.